Peptides (v.31, #6)
Editorial Board (CO2).
Orthologs of magainin, PGLa, procaerulein-derived, and proxenopsin-derived peptides from skin secretions of the octoploid frog Xenopus amieti (Pipidae) by J. Michael Conlon; Nadia Al-Ghaferi; Eman Ahmed; Mohammed A. Meetani; Jérôme Leprince; Per F. Nielsen (989-994).
The Volcano clawed frog Xenopus amieti Kobel, du Pasquier, Fischberg, and Gloor, 1980, with a chromosome number of 2n = 72, is believed to have undergone two rounds of genome duplication since evolving from a diploid ancestor. Nine peptides with differential antimicrobial activity against Escherichia coli and Staphylococcus aureus were isolated from norepinephrine-stimulated skin secretions of X. amieti that showed structural similarity to peptides previously isolated from the tetraploid frog X. laevis (2n = 36) and the diploid frog Silurana (formerly Xenopus) tropicalis (2n = 20). Two peptides (magainin-AM1 and -AM2) are othologous to the magainins, two peptides (PGLa-AM1 and -AM2) orthologous to peptide glycine–leucine-amide, four peptides (CPF-AM1, -AM2, -AM3, -AM4) orthologous to caerulein-precursor fragments, and one peptide (XPF-AM1) structurally similar to xenopsin-precursor fragments were characterized. CFP-AM1 (GLGSVLGKALKIGANLL.NH2) was the most potent peptide present in the secretions and magainin-AM2 (GVSKILHSAGKFGKAFLGEIMKS) was the most abundant. The data indicate that nonfunctionalization has been the most common fate of duplicated antimicrobial peptide genes following the polyploidization events in the X. amieti lineage. However, the very low antimicrobial activity of the magainin-AM1 and PGLa-AM2 paralogs suggests the possibility that certain peptides may have evolved toward a new, as yet undetermined, function (neofunctionalization).
Keywords: Antimicrobial; Frog skin; Magainin; PGLa; Procaerulein; Proxenopsin; Polyploidy;
Structure and function relationship of toxin from Chinese scorpion Buthus martensii Karsch (BmKAGAP): Gaining insight into related sites of analgesic activity by Yong Cui; Gui-Li Guo; Lin Ma; Nan Hu; Yong-Bo Song; Yan-Feng Liu; Chun-Fu Wu; Jing-Hai Zhang (995-1000).
In this study, an effective Escherichia coli expression system was used to study the role of residues in the antitumor-analgesic peptide from Chinese scorpion Buthus martensii Karsch (BmKAGAP). To evaluate the extent to which residues of the toxin core contribute to its analgesic activity, nine mutants of BmKAGAP were obtained by PCR. Using site-directed mutagenesis, all of these residues were individually substituted by one amino acid. These were then subjected to a circular dichroism analysis, and an analgesic activity assay in mice. This study represents a thorough mapping and elucidation of the epitopes that underlie the molecular basis of the analgesic activity. The three-dimensional structure of BmKAGAP was established by homology modeling. Our results revealed large mutant-dependent differences that indicated important roles for the studied residues. With our ongoing efforts for establishing the structure and analgesic activity relationship of BmKAGAP, we have succeeded in pinpointing which residues are important for the analgesic activity.
Keywords: Analgesic activity; BmKAGAP; Circular dichroism; Homology modeling; Structure–function relationship; Site-directed mutagenesis;
Novel conopeptides in a form of disulfide-crosslinked dimer by Xue-Chen Wu; Mi Zhou; Can Peng; Xiao-Xia Shao; Zhan-Yun Guo; Cheng-Wu Chi (1001-1006).
In our present work, seven conotoxins and conopeptides were cloned from four cone snail species based on the M-superfamily signal peptides. Among them, two conopeptides, Vt3.1 and Vt3.2, showed unusual sequence characteristics. Both of them contained two cysteines that are separated by just one non-cysteine residue. In vitro, the chemically synthesized Vt3.1 formed dimers with different intermolecular disulfide linkages. Only the dimer with crossed disulfides showed bioactivity when injected into the intraventricular region of mice brains. Therefore, Vt3.1 and Vt3.2 represent a new group of conopeptides that form disulfide-crosslinked dimers in vitro and probably in vivo.
Keywords: Conopeptide; Dimer; Disulfide; M-superfamily;
Peptidergic modulation of serotonin and nerve elicited responses of the salivary duct muscle in the snail, Helix pomatia by T. Kiss; L. Hernádi; Z. László; Zs.N. Fekete; K. Elekes (1007-1018).
In the present study, the ability of a range of endogenous neuropeptides to modulate neuromuscular transmission was examined in the salivary duct neuromuscular preparation of the terrestrial snail, Helix pomatia. Immunohistochemical and physiological techniques were used to localize the neuropeptides (GSPYFVamide, CARP, FMRFamide and APGWamide) and to investigate whether contractions elicited by the stimulation of the salivary nerve or by exogenously applied 5-HT are subject to peptidergic modulation. All of the neuropeptides studied decreased the tonus by a direct action on the muscle fibers in a concentration dependent manner in a range of 10−9 to 10−6 M. Neuropeptides distinctly affected the 5-HT evoked contraction or relaxation and GSPYFVa and APGWa decreased also the amplitude of contractions elicited by the stimulation of the salivary nerve. All four neuropeptides facilitated the relaxation phase providing further evidence for the postsynaptic action of neuropeptides. Low Ca2+/high Mg2+ saline abolished the nerve-elicited contractions, however the denervated muscle retained the ability to contract due to the mobilization of the Ca2+ from intracellular stores. It was concluded, that peptides belonging to different peptide families exerted their effects through pre- and postsynaptic mechanisms. The modulatory effect of neuropeptides can be assigned to the partial co-localization of 5-HT and neuropeptides in the nerves innervating muscles of the salivary duct, as it was demonstrated by double-labeling immunohistochemistry. A double origin of the 5-HTergic innervation was demonstrated, including efferents originating from both the cerebral and visceral ganglia.
Keywords: Neuropeptides; Mollusks; Modulation; Serotonin; Salivary duct; Muscle;
Shrimp anti-lipopolysaccharide factor peptide enhances the antitumor activity of cisplatin in vitro and inhibits HeLa cells growth in nude mice by Ming-Ching Lin; Shih-Bin Lin; Jian-Chyi Chen; Cho-Fat Hui; Jyh-Yih Chen (1019-1025).
The antitumor activity of the shrimp anti-lipopolysaccharide factor (SALF), an antimicrobial peptide, was not previously examined. In this study, a synthetic SALF was tested for antitumor activity using HeLa cells as the study model. We show that the SALF inhibited the proliferation of HeLa cells and reduced colony formation in a soft agar assay. An enhanced effect was observed when the SALF and cisplatin were used in combination, which caused significant inhibition of HeLa cells. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that the SALF altered the membrane structure similar to what a lytic peptide does. A flow cytometric analysis, qRT-PCR, and Western blotting showed that the SALF induced apoptosis, activated caspases-6, -7, and -9, and downregulated Bcl-2 and nuclear factor (NF)-κB suggesting that the SALF induces apoptosis through the death receptor/NF-κB signaling pathway. An in vivo analysis revealed that the SALF displayed significant tumor suppressive activity in mice with tumor xenografts. Overall, these results indicated that the SALF possesses the potential to be a novel therapeutic agent for treating cervical cancer.
Keywords: Anti-lipopolysaccharide factor; Inhibition; Tumor growth; Cisplatin;
Antiviral activity by fish antimicrobial peptides of epinecidin-1 and hepcidin 1–5 against nervous necrosis virus in medaka by Yi-Da Wang; Chun-Wei Kung; Jyh-Yih Chen (1026-1033).
The nervous necrosis virus (NNV)-medaka infection model was used in this study for analysis of NNV infection and treatment of NNV with the antimicrobial peptides (AMPs) of epinecidin-1 and hepcidin 1–5 at the organismal level. Our results showed that co-treatment of AMPs with the virus was effective in promoting a significant increase in medaka survival. Re-challenge with the virus also showed high survival suggesting that these two AMPs enhanced fish survival. However, pretreatment or post-treatment with AMPs showed that both of these AMPs increased medaka survival and suggested that AMPs can be used as drugs to rescue infected medaka. The data presented here indicate that epinecidin-1 and hepcidin 1–5 have in vivo antivirus activity against the NNV, and hepcidin 1–5 functions like a lytic peptide after an in vitro assay. Infection after pretreatment, co-treatment, and post-treatment with epinecidin-1 or hepcidin 1–5 was verified by RT-PCR which showed both peptides can downregulate NNV and interferon gene expressions. In addition, our results suggest that epinecidin-1 or hepcidin 1–5 may prove to be an effective chemotherapeutic agent for aquaculture in the future.
Keywords: Epinecidin-1; Hepcidin 1–5; Nervous necrosis virus; Medaka;
Structural diversity of the gnih/gnih receptor system in teleost: Its involvement in early development and the negative control of LH release by Yong Zhang; Shuisheng Li; Yun Liu; Danqi Lu; Huapu Chen; Xigui Huang; Xiaochun Liu; Zining Meng; Haoran Lin; Christopher H.K. Cheng (1034-1043).
Gonadotropin inhibitory hormone (GnIH), via binding to GnIH receptor (GnIHR), plays a negative role on the avian and mammalian reproductive axis by inhibiting luteinizing hormone (LH) release. However, the biological significance of the GnIH/GnIHR system in other vertebrates is controversial. To demonstrate the presence of such a system in teleost, we have identified the orthologous gnih genes in zebrafish, stickleback, medaka and Takifugu. Three orthologous genes (gnihr1, gnihr2 and gnihr3) for the gnihr were also identified in zebrafish. The zebrafish gnih precursor contains three putative LPXRFamide peptides. The three zebrafish gnihrs are typical seven transmembrane G protein-coupled receptors sharing high sequence homology with the mammalian and avian GnIHRs (GPR147). Tissue expression studies revealed that zebrafish gnih is mainly expressed in the brain, eye, testis, ovary and spleen, corroborating largely with the tissue expression patterns of the gnihrs in zebrafish. The expression patterns of gnih and its receptors at different developmental stages of zebrafish were also studied. Gnih expression first appeared in the prim-5 stage, and thereafter maintained at a relatively constant level. The three gnihrs could be detected at all embryonic stages of zebrafish and also during early development after hatching. The biological action of the teleost gnih on LH release was further investigated in goldfish in vivo. Intraperitoneal administration of the mature zebrafish gnih peptide (LPXRFa peptide-3) could significantly reduce the basal serum LH level in goldfish. These results provided the first evidence that gnih plays an important role in the negative regulation of LH release in teleost.
Keywords: RFamide-related peptide; gnih; gnih receptor; Teleost; LH release;
Central leptin treatment modulates brain glucosensing function and peripheral energy metabolism of rainbow trout by Ariel J. Aguilar; Marta Conde-Sieira; Sergio Polakof; Jesús M. Míguez; José L. Soengas (1044-1054).
The aim of the present study was to obtain evidence for the possible modulatory effect of leptin on glucosensing capacity in hypothalamus and hindbrain of rainbow trout. In a first experiment, trout were injected ICV with saline alone or containing increased doses of leptin (0.3–30 μg μl−1). Leptin induced in general in both hypothalamus and hindbrain dose-dependent changes in parameters related to glucosensing (increased glycogenic and glycolytic potentials together with increased GK activity, and increased mRNA levels of genes involved in glucosensing response) compatible with those occurring under hyperglycemic conditions, a situation that is known to produce anorexia. The anorectic action of leptin in our experimental conditions was observed in a second experiment. The specificity of leptin action was tested in a third experiment in which trout were injected ICV with saline, or leptin alone, or leptin plus agents known to inhibit leptin signaling pathways in mammals. The results obtained suggest that the central action of leptin on glucosensing system can be related to the JAK/STAT and IRS-PI(3)K pathways. Finally, we also provide evidence for a peripheral effect of central leptin treatment (increased liver glycogenolytic potential), which could be associated with increased sympathetic activity.
Keywords: Rainbow trout; Glucosensor; Leptin; Food intake; Hypothalamus; Hindbrain;
Peripheral administration of pancreatic polypeptide inhibits components of food-intake behavior in dogs by Helena Åkerberg; Bengt Meyerson; Marie Sallander; Anne-Sofie Lagerstedt; Åke Hedhammar; Dan Larhammar (1055-1061).
Pancreatic polypeptide (PP) belongs to the neuropeptide Y (NPY) family of peptides and is released from pancreatic F cells postprandially. PP functions as a peptide hormone and has been associated with decreased food intake in humans and rodents. Our study describes the effects of PP on feeding behavior in dogs, whose mammalian order (Carnivora) is more distantly related to primates and rodents than these are to each other. Furthermore, obesity is becoming more prevalent in dogs which makes knowledge about their appetite regulation highly relevant. Repeated peripheral administration of physiological doses of PP (three injections of 30 pmol/kg each that were administered within 30 min) to six male beagle dogs prolonged the median time spent eating three servings of food by 19% but resulted in no reduction of food intake. In addition, PP decreased the duration of food-seeking behavior after the first serving by 71%. Thus, a physiological dose of PP seems to decrease both the appetitive and the consummatory drive in dogs.
Keywords: Pancreatic polypeptide; Appetite; Satiety; Feeding; Food intake; Dog;
A novel cyclopeptide from the cyclization of PACAP(1–5) with potent activity towards PAC1 attenuates STZ-induced diabetes by Rongjie Yu; Jingjing Wang; Juan Li; Ye Wang; Huahua Zhang; Jiansu Chen; Lin Huang; Xiaofei Liu (1062-1067).
The N-terminal deletion of pituitary adenylate cyclase-activating polypeptide (PACAP)(1–5) generates its own antagonist. The cyclopeptide C*HSDGIC*, which results from the cyclization of PACAP(1–5) with disulfide, was designed and synthesized. CHO cells expressing a PAC1 N/R splice variant (PAC1-CHO) were used to detect the potent activation of PAC1 by C*HSDGIC*. In vitro cell assays showed that C*HSDGIC* stimulated cAMP production and increased the viability of PAC1-CHO cells at micromolar concentrations, about 1000 fold that of PACAP. PACAP(6–38) blocked the effects of PACAP on the proliferation of PAC1-CHO cells but did not interfere with the effects of C*HSDGIC*, suggesting that the activation of PAC1 by C*HSDGIC* was independent of the binding of PAC1 to the C-terminus of PACAP. In experiments in vivo, 10 μmol/kg C*HSDGIC* decreased the plasma glucose level, increased the plasma insulin level and improved glucose tolerance significantly (P < 0.01) when co-injected with STZ for 5 days. The results of these in vitro and in vivo studies of the biological characteristics of C*HSDGIC* reveal that it is a potent activator of PAC1.
Keywords: PACAP; Cyclization; PAC1; Agonist; STZ-induced diabetes;
The absence of the VPAC2 receptor does not protect mice from Aspergillus induced allergic asthma by A.E. Samarasinghe; S.A. Hoselton; J.M. Schuh (1068-1075).
Allergic asthma is a TH2-mediated disease marked by airway inflammation, increased mucus production, and elevated serum IgE in response to allergen provocation. Among its ascribed functions, the neuropeptide vasoactive intestinal peptide (VIP) is believed to promote a TH2 phenotype when signaling through its VPAC2 receptor. In this study, we assessed the requirement for the VIP/VPAC2 axis in initiating the allergic pulmonary phenotype in a murine model of fungal allergic asthma. C57BL/6 wild-type (WT) and VPAC2 knock-out (KO) mice were sensitized with Aspergillus fumigatus antigen and challenged with an aerosol of live conidia to induce allergic airways disease. WT and KO mice exhibited similar peribronchovascular inflammation, increased number of goblet cells, and elevated serum IgE. However, the absence of VPAC2 receptor resulted in a marked enhancement of MUC5AC mRNA with an associated increase in goblet cells and a reduction in eosinophils in the airway lumen at day 3 when VIP mRNA was undetectable in the KO lung. Sustained elevation of serum IgE was noted in KO mice at day 14, while the level in WT mice declined at this time point. These data suggest that the absence of VPAC2 does not protect mice from developing the signs and symptoms of allergic asthma.
Keywords: Vasoactive intestinal peptide; Matrix metalloproteinase-2; Eosinophil; Vipr2; Allergy; Asthma;
The efficacy of combining feG and galantide in mild caerulein-induced acute pancreatitis in mice by Savio G. Barreto; Colin J. Carati; Ann C. Schloithe; Ronald Mathison; Joseph S. Davison; James Toouli; Gino T.P. Saccone (1076-1082).
We have previously shown that galantide ameliorates mild acute pancreatitis (AP), and the salivary tripeptide analogue, feG, ameliorates severe AP in mice. In this study, we compared the efficacy of combining galantide and feG with that of the individual agents in treating mild AP induced in mice with 7-hourly caerulein injections. Galantide was co-administered with each caerulein injection commencing with the first injection. feG was co-administered with the first injection of caerulein as a single intraperitoneal injection. Combination of the agents was also administered. Control animals received galantide, feG, or saline alone. Pancreata were harvested for histological examination and estimation of myeloperoxidase (MPO) activity. Plasma enzyme activities were measured. Galantide significantly reduced AP-induced hyperenzymemia by 41–49%. The combination of galantide and feG significantly reduced AP-induced hyperenzymemia by 39–40%, whereas feG alone was without effect. Plasma enzyme activity in the control groups was comparable with pre-treatment activity. Galantide, feG, and their combination significantly reduced MPO activity by 83, 44 and 74% respectively, and % abnormal acinar cells by 32, 29 and 36% respectively. This study demonstrates for the first time the beneficial effect of feG in mild caerulein-induced AP. Moreover the data indicate that the hyperenzymemia in mild caerulein-induced AP at 12 h possibly reflect a larger secretory component as compared to enzyme release due to neutrophil-mediated acinar cell damage. The effects of the treatment with both peptides indicate a possible role for galantide in modulating neutrophil chemotaxis/activation and supports the hypothesis that galantide may influence neurogenic inflammation in AP.
Keywords: Tripeptide; feG; Inflammation; Combination;
Rapid modulation of TRH and TRH-like peptide release in rat brain, pancreas, and testis by a GSK-3β inhibitor by Albert Eugene Pekary; Schetema A. Stevens; James D. Blood; Albert Sattin (1083-1093).
Antidepressants have been shown to be neuroprotective and able to reverse damage to glia and neurons. Thyrotropin-releasing hormone (TRH) is an endogenous antidepressant-like neuropeptide that reduces the expression of glycogen synthase kinase-3β (GSK-3β), an enzyme that hyperphosphorylates tau and is implicated in bipolar disorder, diabetes and Alzheimer's disease. In order to understand the potential role of GSK-3β in the modulation of depression by TRH and TRH-like peptides and the therapeutic potential of GSK-3β inhibitors for neuropsychiatric and metabolic diseases, young adult male Sprague–Dawley (SD) rats were (a) injected ip with 1.8 mg/kg of GSK-3β inhibitor VIII (GSKI) and sacrificed 0, 2, 4, 6, and 8 h later or (b) injected with 0, 0.018, 0.18 or 1.8 mg/kg GSKI and bled 4 h later. Levels of TRH and TRH-like peptides were measured in various brain regions involved in mood regulation, pancreas and reproductive tissues. Large, 3–15-fold, increases of TRH and TRH-like peptide levels in cerebellum, for example, as well as other brain regions were noted at 2 and 4 h. In contrast, a nearly complete loss of TRH and TRH-like peptides from testis within 2 h and pancreas by 4 h following GSKI injection was observed. We have previously reported similar acute effects of corticosterone in brain and peripheral tissues. Incubation of a decapsulated rat testis with either GSKI or corticosterone accelerated release of TRH, and TRH-like peptides. Glucocorticoids, via inhibition of GSK3-β activity, may thus be involved in the inhibition of TRH and TRH-like peptide release in brain, thereby contributing to the depressogenic effect of this class of steroids. Corticosterone-induced acceleration of release of these peptides from testis may contribute to the decline in reproductive function and redirection of energy needed during life-threatening emergencies. These contrasting effects of glucocorticoid on peptide release appear to be mediated by GSK-3β.
Keywords: GSK-3β; Thyrotropin-releasing hormone; Limbic system; Testis; HPLC; Radioimmunoassay;
Refinement of the pharmacophore of an agonist ligand of the secretin receptor using conformationally constrained cyclic hexapeptides by Maoqing Dong; Pooja Narang; Delia I. Pinon; Andrew J. Bordner; Laurence J. Miller (1094-1098).
There is a compelling need for the development of small molecule agonists acting at family B G protein-coupled receptors. A possible lead for the development of such drugs was reported when it was recognized that sequences endogenous to the amino terminus of the secretin receptor and certain other receptors in this family possess weak full agonist activity (Dong et al. Mol Pharmacol 2006;70:206–213). In the current report, we extended those observations by building the active dipeptide motif found in the secretin receptor (WD) into each position around a conformationally constrained d-amino acid-containing cyclic hexapeptide, and determining the biological activity of each peptide at the secretin receptor. Indeed, only two positions for WD around this constrained ring resulted in biological activity at the receptor, providing further insights into the structural specificity of this phenomenon. Molecular modeling supported the presence of a unique WD backbone conformation shared only by these active peptides, and provided a more constrained template for future receptor-active agonist drug development.
Keywords: G protein-coupled receptor; Secretin receptor; Receptor activation; Cyclic peptide; Hexapeptide; Molecular modeling;
Endogenous orexin-A modulates gastric motility by peripheral mechanisms in rats by Mehmet Bülbül; Ruken Tan; Burcu Gemici; Sebahat Özdem; İsmail Üstünel; Nuray Acar; V. Nimet İzgüt-Uysal (1099-1108).
Orexin-A (OXA) and orexin receptor type 1 (OX1R) are found in enteric nervous system and smooth muscle cells in the digestive tract. Fasting is a stimulant for OXA synthesis. The aim of the present study was to investigate central and peripheral effects of endogenous OXA on gastric motility. Endogenous OXA synthesis was induced by 36 h fasting. Vagotomy was used to evaluate N.vagus-mediated effects of OXA. Gastric emptying and interdigestive gastric motility were measured by spectrophotometric and manometric methods, respectively. Rats were pretreated with OX1R antagonist SB-334867 prior to measurements. Plasma OXA concentration was assayed with radioimmunoassay while preproorexin (PPO) expression was determined with Western blotting in gastric and hypothalamic tissues. OXA immunoreactivity in antrum was determined with immunohistochemistry. Plasma OXA level, PPO protein expression and OXA immunoreactivity were significantly increased in response to 36 h fasting. Endogenous OXA facilitated gastric emptying and inhibited gastric interdigestive motility. As these effects were abolished with SB-334867, it is likely that gastrokinetic effects of OXA are mediated via OX1R. Vagotomy did not alter OXA-mediated effects. According to current data, OXA is up-regulated both centrally and peripherally upon fasting. Endogenous OXA accelerates gastric emptying while it inhibits interdigestive motility.
Keywords: Fasting; Gastric motility; Orexin-A; Preproorexin;
Covariation of plasma ghrelin and motilin in irritable bowel syndrome by Kristina Sjölund; Rolf Ekman; Nils Wierup (1109-1112).
We have previously shown that ghrelin is mainly localized to the stomach but also occurs, together with the prokinetic hormone motilin, in endocrine cells in the proximal small intestine. This study explored ghrelin and motilin concentrations in plasma in relation to gastrointestinal motility and whether plasma ghrelin is changed in patients with irritable bowel syndrome (IBS). Nine patients with severe IBS and 10 healthy subjects underwent stationary antro-duodeni-jejunal manometry; blood was sampled during similar motility phases in the two groups. The motility phases were monitored and blood samples were collected during fasting and after food intake. Plasma was analyzed for two forms of ghrelin (octanylated and desoctanylated) as well as for motilin. In IBS patients circulating motilin levels covaried with total ghrelin levels (r = 0.90; p < 0.004), octanylated ghrelin (r = 0.77; p < 0.02) and desoctanylated ghrelin (r = 0.69; p < 0.04). No such correlations were seen in the control group. Octanylated ghrelin comprised 35.3 ± 3.9% (mean ± SEM) of the total circulating ghrelin in the IBS patients compared to 40.4 ± 4.5% (mean ± SEM) in the control group (NS). Ghrelin covaried with motilin in plasma in IBS but not in plasma from healthy subjects. This suggests the two peptides act together in IBS.
Keywords: Irritable bowel disease; Gut peptides; Ghrelin; Motilin; Small intestinal manometry;
A novel simultaneous measurement method to assess the influence of intracerebroventricular obestatin on colonic motility and secretion in conscious rats by Chih-Yen Chen; Ming-Luen Doong; Chung-Pin Li; Wen-Jinn Liaw; Hsing-Feng Lee; Full-Young Chang; Han-Chieh Lin; Shou-Dong Lee (1113-1117).
Obestatin, a novel putative 23-amino acid peptide, is derived from mammalian preproghrelin gene via a bioinformatics approach. Although obestatin regulates thirst, sleep, memory, anxiety, activates cortical neurons in the brain and stimulate proliferation of retinal pigment epithelial cells, there is no study to explore its central impacts on the lower gut motility and secretion. We investigated the influence of intracerebroventricular (ICV) injection of obestatin on rat colonic motor and secretory functions. Colonic transit time, fecal pellet output and fecal content were assessed in freely fed, conscious rats, which were implanted with ICV and colonic catheters chronically. Human/rat corticotropin-releasing factor (h/rCRF) was applied as a stimulatory inducer of colonic motility and secretion. ICV injection of obestatin (0.1, 0.3, 1.0 nmol/rat) did not modify the colonic transit time, whereas ICV injection of h/rCRF (0.3 nmol/rat) significantly shortened colonic transit time. ICV obestatin in any dose we tested did not affect the fecal pellet output, frequency of watery diarrhea, total fecal weight, fecal dried solid weight, or fecal fluid weight in the first hour post-injection, either. In contrast, ICV injection of h/rCRF effectively stimulated fecal pellet output, as well as increased total fecal weight, fecal dried solid weight and fecal fluid weight during the first hour post-injection, compared to ICV saline controls. In conclusion, using our novel simultaneous measurement method, acutely central administration of obestatin exhibits no influence on colonic motility and secretion in conscious rats.
Keywords: Obestatin; Colonic transit time; Fecal pellet output; Colonic secretion; Intracerebroventricular;
Peripherally injected CCK-8S activates CART positive neurons of the paraventricular nucleus in rats by Lisa Peter; Andreas Stengel; Steffen Noetzel; Tobias Inhoff; Miriam Goebel; Yvette Taché; Rüdiger W. Veh; Norbert Bannert; Carsten Grötzinger; Bertram Wiedenmann; Burghard F. Klapp; Hubert Mönnikes; Peter Kobelt (1118-1123).
Cholecystokinin (CCK) plays a role in the short-term inhibition of food intake. Cocaine- and amphetamine-regulated transcript (CART) peptide has been observed in neurons of the paraventricular nucleus (PVN). It has been reported that intracerebroventricular injection of CART peptide inhibits food intake in rodents. The aim of the study was to determine whether intraperitoneally (ip) injected CCK-8S affects neuronal activity of PVN-CART neurons. Ad libitum fed male Sprague–Dawley rats received 6 or 10 μg/kg CCK-8S or 0.15 M NaCl ip (n = 4/group). The number of c-Fos-immunoreactive neurons was determined in the PVN, arcuate nucleus (ARC), and the nucleus of the solitary tract (NTS). CCK-8S dose-dependently increased the number of c-Fos-immunoreactive neurons in the PVN (mean ± SEM: 102 ± 6 vs. 150 ± 5 neurons/section, p < 0.05) and compared to vehicle treated rats (18 ± 7, p < 0.05 vs. 6 and 10 μg/kg CCK-8S). CCK-8S at both doses induced an increase in the number of c-Fos-immunoreactive neurons in the NTS (65 ± 13, p < 0.05, and 182 ± 16, p < 0.05). No effect on the number of c-Fos neurons was observed in the ARC. Immunostaining for CART and c-Fos revealed a dose-dependent increase of activated CART neurons (19 ± 3 vs. 29 ± 7; p < 0.05), only few activated CART neuron were observed in the vehicle group (1 ± 0). The present observation shows that CCK-8S injected ip induces an increase in neuronal activity in PVN-CART neurons and suggests that CART neurons in the PVN may play a role in the mediation of peripheral CCK-8S's anorexigenic effects.
Keywords: CCK; CART; c-Fos; Food intake; PVN;
Centrally administered relaxin-3 induces Fos expression in the osmosensitive areas in rat brain and facilitates water intake by Hiroki Otsubo; Tatsushi Onaka; Hitoshi Suzuki; Akiko Katoh; Toyoaki Ohbuchi; Miwako Todoroki; Mizuki Kobayashi; Hiroaki Fujihara; Toru Yokoyama; Tetsuro Matsumoto; Yoichi Ueta (1124-1130).
The expression of the relaxin-3 gene, detected as a new member of the insulin superfamily using human genomic databases, is abundantly present in the brain and testis. Intracerebroventricularly (icv) administered relaxin-3 stimulates food intake. Icv administered relaxin (identical to relaxin-2 in humans) affects the secretion of vasopressin and drinking behavior. Relaxin-3 partly binds relaxin family peptide receptor 1, which is a specific receptor to relaxin. Thus, we hypothesized that relaxin-3 would have physiological effects in the body fluid balance. However, the effects of relaxin-3 in the body fluid balance remain unknown. In the present study, we revealed that icv administered relaxin-3 induced dense Fos-like immunoreactivity (Fos-LI) in the rat hypothalamus and circumventricular organs including the organum vasculosum of the lamina terminalis, the median preoptic nucleus, supraoptic nucleus (SON), the subfornical organ (SFO) and the paraventricular nucleus (PVN), that are related to the central regulation of body fluid balance. Icv administered relaxin-3 (54, 180 and 540 pmol/rat) also induced a significant increase in c-fos gene expression in a dose-dependent manner in the SON, SFO and PVN. Further, icv administered relaxin-3 (180 pmol/rat) significantly increased water intake, and the effect was as strong as that of relaxin-2 (180 pmol/rat). These results suggest that icv administered relaxin-3 activates osmosensitive areas in the brain and plays an important role in the regulation of body fluid balance.
Keywords: Relaxin-3; c-fos; Drinking;
Depolarizing stimuli cause persistent and selective loss of orexin in rat hypothalamic slice culture by Hiroshi Katsuki; Shinsuke Kurosu; Shotaro Michinaga; Akinori Hisatsune; Yoichiro Isohama; Yasuhiko Izumi; Toshiaki Kume; Akinori Akaike (1131-1138).
A hypothalamic neuropeptide orexin (hypocretin) is a critical regulator of physiological processes including sleep/wakefulness and feeding. Using organotypic slice culture of rat hypothalamus, we found that exposure to elevated extracellular concentration of K+ (+10–30 mM) for 24–72 h led to a substantial decrease in the number of neurons immunoreactive for orexin and a co-existing neuropeptide dynorphin-A. In contrast, the same treatment affected neither the number of melanin-concentrating hormone-immunoreactive neurons nor the number of total neurons. A substantial decrease of orexin-immunoreactive neurons was also induced by 72 h treatment with 1–10 μM veratridine, a Na+ channel activator. The effect of elevated K+ was only partially reversible, and that of veratridine was virtually irreversible, although the decrease in orexin immunoreactivity was not associated with signs of cell damage assessed by propidium iodide uptake and Hoechst 33342 nuclear staining. In addition, the level of preproorexin mRNA did not decrease during treatment with elevated K+ or veratridine. After treatment with elevated K+ and veratridine, c-Fos immunoreactivity appeared in orexin-immunoreactive neurons but not in melanin-concentrating hormone-immunoreactive neurons, suggesting selective excitation of orexin neurons. However, the amount of orexin released extracellularly was paradoxically decreased by treatment with elevated K+ and veratridine. Overall, these characteristics of orexin neurons may be taken into consideration to understand the behaviors of these neurons under physiological and pathophysiological conditions.
Keywords: c-Fos; Depolarization; Dynorphin; Hypocretin; Hypothalamus; Melanin-concentrating hormone;
Electrophysiological effect of ghrelin and somatostatin on rat hypothalamic arcuate neurons in vitro by Kyohei Mori; Juhyon Kim; Kazuo Sasaki (1139-1145).
Growth hormone (GH) secretion from the pituitary gland is partly regulated by GH releasing hormone (GHRH)-containing neurons located in the hypothalamic arcuate nucleus (ARC). GHRH-containing neurons express the GH secretagogue (GHS) receptor (GHS-R) and the somatostatin (SRIF) receptor. Recently, an endogenous ligand for the GHS-R named ghrelin was found. Therefore, it seems that both ghrelin and SRIF are involved in the hypothalamic regulation of GH release via GHRH-containing neurons in the ARC. In extracellular single unit recordings from in vitro hypothalamic slice preparations from rats, application of 100 nM ghrelin substantially excited ARC neurons (82.5%), whereas 1 μM SRIF substantially inhibited them (81.8%). The ghrelin-induced excitatory and SRIF-induced inhibitory effects on ARC neurons were dose-dependent and persisted during synaptic blockade using low-Ca2+/high-Mg2+ solution. In addition, the effects were antagonized by [D-Lys3]-GHRP-6, a GHS-R antagonist, and CYN154806, a SRIF receptor subtype sst2 antagonist, respectively. When ghrelin and SRIF were sequentially applied to ARC neurons, 95.2% were excited by ghrelin and inhibited by SRIF. Similarly, 85.0% of ARC neuroendocrine cells that project to the median eminence were excited by ghrelin and inhibited by SRIF. These results indicate that ARC neuroendocrine cells projecting to the median eminence are dose-dependently, postsynaptically and oppositely regulated by ghrelin through GHS-R and SRIF via the SRIF sst2 receptor subtype. Our results also suggest that most of these ARC neuroendocrine cells are presumably GHRH-containing neurons and are involved in the cellular processes through which ghrelin and SRIF participate in the hypothalamic regulation of GH release.
Keywords: Ghrelin; Somatostatin; [D-Lys3]-GHRP-6; CYN154806; Arcuate nucleus; Neuroendocrine cells; Median eminence;
Inhibition of L-type calcium currents by salusin-β in rat cardiac ventricular myocytes by Jing-Song Shi; Dong Li; Ning Li; Li Lin; Yong-Ji Yang; Ying Tang; Tao Sun; Wen-Jun Yuan; An-Jing Ren (1146-1149).
Salusin-β is a new regulatory peptide relevant to the cardiovascular system and exerts negative inotropic effect on ventricular muscle. The purpose of the present study was to determine whether salusin-β can inhibit cardiac L-type calcium channel current (I Ca,L). Using whole-cell voltage-clamp techniques, I Ca,L was measured in ventricular myocytes isolated from 12 to 16 weeks rats. Salusin-β dose-dependently and reversibly reduced the magnitude of I Ca,L in rat ventricular myocytes. Neither threshold potential nor the peak potential of current–voltage relationship was affected. Salusin-β increased the rate of I Ca,L inactivation without altering its gating properties. These results suggest salusin-β inhibited I Ca,L by increasing the rate of I Ca,L inactivation and the inhibition of L-type Ca2+ channels induced by salusin-β may contribute to its negative inotropic effect on ventricular muscle.
Keywords: Calcium channel; Salusin-β; Myocytes; Rat;
Adrenomedullin ameliorates the development of atherosclerosis in apoE−/− mice by Chun Shui Pan; Jing Zhang; Fang Yu; Xu Teng; Chang Qi Cao; Wei Wu; Chao Shu Tang; Yong Fen Qi (1150-1158).
Adrenomedullin (ADM) is a multifunctional peptide regulating cardiovascular homeostasis. We studied the role of ADM in the pathogenesis of atherosclerosis by investigating changes in ADM and its receptors – calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) – in aorta of apoE−/− mice and the effect of exogenous ADM administration. ApoE−/− mice were fed an atherogenic diet for 4 weeks, and apoE−/− + ADM mice were additionally given subcutaneous injections of ADM, 300 ng/kg/h, for 4 weeks. ApoE−/− mice fed an atherogenic diet showed hyperlipidemia, a large plaque area and increased vessel wall thickness. The mRNA expression and protein level of ADM/ADM receptors were increased in the aorta, compared with C57BL/6J mice. The elevated mRNA level of CRLR and RAMPs correlated positively with ADM mRNA level. Radioimmunoassay revealed a higher plasma and aorta ADM content, by 61.6% and 285% (both P < 0.01), respectively, in apoE−/− mice than that in C57BL/6J mice. Exogenous ADM significantly ameliorated dyslipidemia in apoE−/− mice. ADM-treated mice showed fewer aortic plaques, decreased plaque area, by 76% (P < 0.01), and reduced ratio of plaque area to luminal area, by 65% (P < 0.01), and ultrasonography revealed significantly reduced intima-media thickness of the ascending branch and abdominal aorta. The results suggest that atherosclerotic apoE−/− mice fed an atherogenic diet showed upregulated endogenous ADM and its receptors, and exogenous ADM treatment ameliorated the dyslipidemia and vascular atherosclerotic lesions. ADM/ADM receptors might be an important protective system against atherosclerosis and could become a new target of prevention and therapy for atherosclerosis.
Keywords: Adrenomedullin; Atherosclerosis; Calcitonin receptor-like receptor; Receptor activity-modifying proteins; ApoE−/− mice;
Src tyrosine kinase regulates angiotensin II-induced protein kinase Cζ activation and proliferation in vascular smooth muscle cells by Li Li; Yun Zhou; Cheng Wang; Ya-Li Zhao; Zhi-Guo Zhang; Dong Fan; Xiao-Bing Cui; Li-Ling Wu (1159-1164).
Protein kinase Cζ (PKCζ) isoform plays a critical role in angiotensin II (AngII)-elicited extracellular signal-regulated kinase 1/2 (ERK1/2) activation and proliferation in vascular smooth muscle cells (VSMCs). However, the exact signal transduction mechanism by which AngII activates PKCζ has not been clarified. In this study, we investigated the role of Src in PKCζ activation and VSMCs proliferation induced by AngII. AngII-induced rapid activation of PKCζ, which was associated with its phosphorylation and nuclear translocation. AngII not only induced Src activation but also promoted the physical association between Src and PKCζ, which was abolished by Src inhibition with PP2. Src inhibition also abrogated AngII-stimulated PKCζ activation, ERK1/2 phosphorylation and VSMCs proliferation. In conclusion, Src kinase plays an important role in AngII-elicited PKCζ activation and the subsequent downstream signaling including ERK1/2 activation and VSMCs proliferation.
Keywords: Angiotensin II; Src; Protein kinase Cζ; Vascular smooth muscle cells;
Arachin derived peptides as selective angiotensin I-converting enzyme (ACE) inhibitors: Structure–activity relationship by V.K. Jimsheena; Lalitha R. Gowda (1165-1176).
Current attention focuses on mechanisms of controlling blood pressure through the inhibition of angiotensin I-converting enzyme (ACE). Bioactive antihypertensive peptides of food origin are increasingly gaining importance as alternates to synthetic drugs in hypertension therapy. The ACE inhibitory property of an enzymatic digest of arachin, the major storage globulin of peanut (Arachis hypogaea) has been demonstrated. The ACE inhibitory activity of a tripeptide (IEY) isolated from these digests has been characterized. Five synthetic structural analogs of this peptide (IEW, IKY, IKW, IEP and IKP) were assembled and their ACE inhibitory activity evaluated. Among these, the tripeptide IKP was a potent competitive inhibitor with an IC50 of 7 ± 1 × 10−6 M similar to that of the potent whey peptides IPP and VPP. The inhibition data of these peptide analogs have been rationalized through docking simulations using the tACE–lisinopril complex at 2 Å resolution (PDB: 1086). The best docking poses were located at the tACE catalytic site resembling the mode of inhibition exerted by lisinopril, the synthetic drug. The degree of inhibition by the peptides correlated with the coordination distance between the catalytic Zn(II) and the carbonyl oxygen of the peptide bond between the amino-terminal and middle residue. These studies illustrate that these peptides, like lisinopril, behave as transition state analog inhibitors and are useful in therapeutic intervention for blood pressure management.
Keywords: Bioactive peptides; Hypertension; Tripeptide inhibitors; Molecular docking; Protease-P; Arachis hypogaea;
Changed salt appetite and central angiotensin II-induced cellular activation in rat offspring following hypoxia during fetal stages by Weili Yang; Caiping Mao; Fei Xia; Jianli Zheng; Aiqing Wang; Liyan Zhu; Rui He; Zhice Xu (1177-1183).
Hypoxia in pregnancy may induce fetal growth restriction and cause functional abnormalities during development. The present study determined the long-term influence of hypoxia in fetal life on dipsogenic behavior linked to central angiotensin (Ang) network in the offspring rats. Fetal blood pO2 and body weight were decreased by hypoxia during pregnancy, followed by a postnatal “catch-up” growth. Subcutaneous hypertonic saline or intracerebroventricular Ang II significantly increased salt intake in the offspring prenatally exposed to hypoxia, while water intake was the same between the two groups. Ang II-induced c-fos expression was detected in the paraventricular nuclei, median preoptic nuclei, supraoptic nuclei, and subfornical organ in the brain, in association with reduced forebrain AT2 receptor protein abundance in the offspring prenatally exposed to hypoxia. Levels of central AT1 receptor protein were not changed between the two groups. Hypoxia during pregnancy could be linked to developmental problems related to behavioral dysfunctions in body fluid regulations in later life, in association with the change in central angiotensin II-mediated neural activation and expression of the Ang II receptor in the brain.
Keywords: Hypoxia; Appetite; Ang II receptor; Programming;
Antidepressant-like or anxiolytic-like actions of topiramate alone or co-administered with intra-lateral septal infusions of neuropeptide Y in male Wistar rats by Miguel Molina-Hernández; N. Patricia Téllez-Alcántara; Jorge I. Olivera-Lopez; M. Teresa Jaramillo (1184-1189).
We tested the effects of intra-lateral septal infusions of neuropeptide Y (NPY) combined with systemic injections of topiramate in the DRL-72 s paradigm and the elevated plus-maze test in male Wistar rats. Intra-lateral septal infusions of desipramine (5.0 μg/μl; P < 0.05) or intra-lateral septal infusions of NPY (3.0 μg/μl, P < 0.05; 3.5 μg/μl, P < 0.05) or systemic injections of topiramate (20.0 mg/kg, P < 0.05; 30.0 mg/kg, P < 0.05) or subthreshold doses of topiramate (10.0 mg/kg) combined with intra-lateral septal infusions of subthreshold doses of NPY (2.5 μg/μl; P < 0.05) induced a dose-dependent increase in reinforced lever presses and a cohesive rightward shift of the inter-response time distribution in the DRL 72 s task. In the elevated plus-maze test, intra-lateral septal infusions of NPY (3.0 μg/μl, P < 0.05; 3.5 μg/μl, P < 0.05) or midazolam (10.0 μg/μl; P < 0.05) or systemic injections of topiramate (20.0 mg/kg, P < 0.05; 30.0 mg/kg, P < 0.05) or subthreshold doses of systemic injections of topiramate (10.0 mg/kg) combined with intra-lateral septal infusions of subthreshold doses of NPY (2.5 μg/μl; P < 0.05) increased the exploration of the open arms without affecting locomotion. In conclusion, intra-septal NPY has anxiolytic effects in the EPM, and antidepressant effects in the DRL 72 s test. Similarly, systemic topiramate has anxiolytic effects in the EPM, and antidepressant effects in the DRL 72 s test. Finally, a combination of subthreshold doses of NPY and topiramate together also have anxiolytic and antidepressant effects, suggesting a synergistic effect.
Keywords: Antidepressant-like; Anxiolytic-like; DRL-72 s; Elevated plus-maze; Lateral Septum; Neuropeptide Y; Topiramate;
Ghrelin and memory: Differential effects on acquisition and retrieval by Valeria P. Carlini; Marisa Ghersi; Helgi B. Schiöth; Susana R. de Barioglio (1190-1193).
In a previous paper we have demonstrated that the orexigenic peptide Ghrelin (Ghr), increases memory retention in rats and mice. In the present work we evaluated the Ghr effect when it was administered previous the training session or previous the test session (24 h after training) on the memory performance, using step-down test. The results showed that the intra-hippocampal Ghr administration previous the training session improved the long-term memory in this task, but did not modify the short-term memory. Nevertheless, when the Ghr was administrated previous the test session, no changes were observed in the memory performance. Taking into account these results and other previously published by our group, we could hypothesizes that Ghr may modulate specific molecular intermediates involved in memory acquisition/consolidation but not in the retrieval.
Keywords: Ghrelin; Memory retention; Memory acquisition; Short-term memory; Long-term memory;
Pharmacological profile and antiparkinsonian properties of the novel nociceptin/orphanin FQ receptor antagonist 1-[1-cyclooctylmethyl-5-(1-hydroxy-1-methyl-ethyl)-1,2,3,6-tetrahydro-pyridin-4-yl]-3-ethyl-1,3-dihydro-benzoimidazol-2-one (GF-4) by Mattia Volta; Matteo Marti; John McDonald; Stefano Molinari; Valeria Camarda; Michela Pelà; Claudio Trapella; Michele Morari (1194-1204).
In this study we provided a pharmacological characterization of the recently synthesized nociceptin/orphanin FQ (N/OFQ) peptide receptor (NOP) antagonist 1-[1-Cyclooctylmethyl-5-(1-hydroxy-1-methyl-ethyl)-1,2,3,6-tetrahydro-pyridin-4-yl]-3-ethyl-1,3-dihydro-benzoimidazol-2-one (GF-4) and investigated its antiparkinsonian properties. GF-4 inhibited N/OFQ binding to CHOhNOP cell membranes (pK i 7.46), and antagonized N/OFQ effects in a calcium mobilization assay and electrically stimulated isolated tissues (pK B 7.27–7.82), showing a ∼5-fold selectivity over classical opioid receptors. In vivo, GF-4 dually modulated stepping activity in wild-type mice, causing facilitation in the 0.01–10 mg/kg dose range and inhibition at 30 mg/kg. These effects were mediated by NOP receptors since GF-4 was ineffective in NOP receptor knock-out mice. Antiparkinsonian properties of GF-4 were investigated in 6-hydroxydopamine hemilesioned rats. GF-4 ameliorated akinesia, bradykinesia and overall gait ability in the 0.1–10 mg/kg dose range, but inhibited motor activity at 30 mg/kg. To investigate the circuitry underlying motor facilitating and inhibitory effects of GF-4, microdialysis coupled to behavioral testing (akinesia test) was performed. An anti-akinetic dose of GF-4 (1 mg/kg) reduced glutamate (GLU) and enhanced GABA release in SNr, while the pro-akinetic dose of GF-4 (30 mg/kg) evoked opposite effects. Moreover, the anti-akinetic dose of GF-4 reduced GABA and increased GLU release in ventro-medial thalamus, the pro-akinetic dose decreasing GABA without affecting GLU release in this area. We conclude that GF-4 is an effective NOP receptor antagonist able to attenuate parkinsonian-like symptoms in vivo via inhibition of the nigro-thalamic pathway.
Keywords: 6-Hydroxydopamine; Microdialysis; Nociceptin/orphanin FQ; NOP receptor knock-out; Parkinson's disease; GF-4;
Effect of statin therapy on leptin levels in patients with coronary heart disease by Yan-Ming Sun; Jia Li; Ying Luan; Lan-Feng Wang (1205-1207).
The goal of this study was to investigate the effects of simvastatin on the levels of plasma leptin and nitric oxide (NO) in patients with coronary heart disease (CHD). The study population consisted of 65 patients with CHD and 48 control individuals without signs or symptoms of CHD. The patients with CHD were treated with simvastatin 20 mg/day. Fasting serum lipids, leptin and NO were determined before and after 12 weeks of treatment. Leptin levels were higher in patients with CHD than control (P < 0.05). Statin treatment significantly decreased plasma lipids and leptin levels and increased NO concentration in all CHD patients (P < 0.05). Serum leptin levels after treatment correlated negatively with the NO concentration (P < 0.05). Simvastatin may provide beneficial effects of reducing leptin levels, independent of its lipid-lowering action, which may play an important role in patients with CHD.
Keywords: HMG-COA reductase inhibitor; Leptin; Coronary heart disease;
Surgery and sepsis increase somatostatin-like immunoreactivity in the human plasma by Balazs Suto; Terez Bagoly; Rita Borzsei; Orsolya Lengl; Janos Szolcsanyi; Timea Nemeth; Csaba Loibl; Zsofia Bardonicsek; Erika Pinter; Zsuzsanna Helyes (1208-1212).
We have previously shown in animals that somatostatin released from capsaicin-sensitive afferents in response to inflammation and tissue damage exerts systemic anti-nociceptive and anti-inflammatory actions. Since peptidergic sensory innervation of the airways and the joints are particularly dense, we aimed at investigating the alterations of plasma somatostatin-like immunoreactivity (SST-LI) in response to thoracic and orthopedic surgery, as well as sepsis. Thoracotomy, video-assisted thoracoscopy, hip and knee endoprosthesis were performed under general anesthesia. Blood was taken before, during and after the surgical procedures, as well as at admission and every consecutive morning from septic patients receiving exclusively total parenteral nutrition. SST-LI was determined from the plasma with specific and sensitive radioimmunoassay developed in our laboratory. Plasma SST-LI in healthy volunteers and preoperatively was 8–12 fmol/ml. Both thoracotomy and thoracoscopy significantly increased SST-LI by 55–60% at the end of the procedures when the thoracic cavity and the skin were closed. Hip endoprosthesis implantation elevated SST-LI by 30% after skin incision, which increased further to 55% by the time the surgery was completed. In contrast, knee operations performed under tourniquet did not alter SST-LI in the systemic circulation. SST-LI was almost 3-fold higher in the plasma of septic patients than in healthy volunteers. This human study revealed that thoracic/hip surgery and sepsis elevate SST-LI in the systemic circulation, presumably by inducing its release from sensory fibres. It is concluded, that the endogenous protective mechanism mediated by neural somatostatin, which has been evidenced in animals, is likely to operate in patients.
Keywords: Somatostatin-like immunoreactivity; Thoracic and orthopedic surgery; Sepsis; Radioimmunoassay; Sensory nerves;
Induction of apoptosis by plant natriuretic peptides in rat cardiomyoblasts by Yu Hua Wang; Hassiba Ahmar; Helen R. Irving (1213-1218).
Atrial natriuretic peptide (ANP) has an important role in maintaining the homeostasis of body fluids and blood pressure and also in preventing cardiac hypertrophy and initiating the process of apoptosis. An immunoreactive analog of ANP was discovered in plants over a decade ago and termed plant natriuretic peptide (PNP). PNP is a small protein that contains sequence and structural similarity to ANP within a predicted protruding psi (ψ) loop. Since application of ANP or PNP stimulates similar functional effects in plants, it is conceivable that PNP may have effects on mammalian cells. In this report, we show that purified recombinant PNP induces apoptosis in a dose dependent and cell type specific manner. Rat cardiac myoblasts (H9c2 cells) were more susceptible to the apoptotic promoting effects of PNP and ANP than HEK-293T cells where PNP had a protective effect at lower concentrations. Similarly rat thoracic myoblasts (A-10) were less responsive to both PNP and ANP than the H9c2 cells. Since PNP is mimicking the effect of ANP in this instance, PNP may prove to be a useful lead molecule for developing novel therapeutic natriuretic peptides.
Urotensin-II as an angiogenic factor by Diego Guidolin; Giovanna Albertin; Domenico Ribatti (1219-1224).
Angiogenesis, the process through which new blood vessels arise from pre-existing ones, is regulated by numerous “classic” factors and other “nonclassic” regulators of angiogenesis. Among these latter urotensin-II is a cyclic 11-amino acid (human) or 15-amino acid (rodent) peptide, originally isolated from the fish urophysis, which exerts a potent systemic vasoconstrictor and hypertensive effect. This review article summarizes the literature data concerning the involvement of urotensin-II in angiogenesis.
Keywords: Angiogenesis; Antiangiogenesis; Urotensin;