Peptides (v.44, #C)
Editorial Board (CO2).
Gayle and Richard Olson prize pages (III-IV).
Leptin in nucleus of the solitary tract alters the cardiovascular responses to aortic baroreceptor activation by John Ciriello (1-7).
Recent data suggests that neurons expressing the long form of the leptin receptor form at least two distinct groups within the caudal nucleus of the solitary tract (NTS): a group within the lateral NTS (Slt) and one within the medial (Sm) and gelantinosa (Sg) NTS. Discrete injections of leptin into Sm and Sg, a region that receives chemoreceptor input, elicit increases in arterial pressure (AP) and renal sympathetic nerve activity (RSNA). However, the effect of microinjections of leptin into Slt, a region that receives baroreceptor input is unknown. Experiments were done in the urethane-chloralose anesthetized, paralyzed and artificially ventilated Wistar or Zucker obese rat to determine leptin's effect in Slt on heart rate (HR), AP and RSNA during electrical stimulation of the aortic depressor nerve (ADN). Depressor sites within Slt were first identified by the microinjection of l-glutamate (Glu; 0.25 M; 10 nl) followed by leptin microinjections. In the Wistar rat leptin microinjection (50 ng; 20 nl) into depressor sites within the lateral Slt elicited increases in HR and RSNA, but no changes in AP. Additionally, leptin injections into Slt prior to Glu injections at the same site or to stimulation of the ADN were found to attenuate the decreases in HR, AP and RSNA to both the Glu injection and ADN stimulation. In Zucker obese rats, leptin injections into NTS depressor sites did not elicit cardiovascular responses, nor altered the cardiovascular responses elicited by stimulation of ADN. Those data suggest that leptin acts at the level of NTS to alter the activity of neurons that mediate the cardiovascular responses to activation of the aortic baroreceptor reflex.
Keywords: Leptin receptors; Cardiovascular reflex pathways; Aortic depressor nerve; Obesity; Leptin;
CRHR1 mediates p53 transcription induced by high altitude hypoxia through ERK 1/2 signaling in rat hepatic cells by Yang Zhao; Ming-Yang Wang; Ke Hao; Xue-Qun Chen; Ji-Zeng Du (8-14).
We have previously reported that hypoxia activates corticotrophin-releasing hormone (CRH) and the expression of its type-1 receptor (CRHR1) and induces disorders of the brain–endocrine–immune network. p53 is activated by hypoxia and involved in tumorigenesis and apoptosis. Whether CRHR1 regulates p53 transactivation to further influence apoptotic genes remains unclear. Here, we showed that hypoxia at a simulated altitude of 5 km or 7 km for 8 and 24 h increased p53 protein and mRNA, and reduced apoptotic bax and IGFBP3 gene expression while upregulating the cell-arrest gene p21 for 8 h in rat liver cells. The upregulation of p53 mRNA and downregulation of bax mRNA induced by hypoxia were blocked by pretreatment with the specific CRHR1 antagonist CP-154,526, but the downregulation of IGFBP3 and upregulation of p21 mRNA were not. Furthermore, CRH stimulated p53 mRNA via the ERK 1/2 pathway in the BRL-3A cell line and this was blocked by the ERK 1/2 antagonist U0126. These data provide novel evidence that the CRHR1-triggered ERK 1/2 pathway is involved in the activation of p53 and suppression of the apoptotic bax gene by hypoxia in rat liver.
Keywords: Corticotropin-releasing hormone receptor-1; Hypoxia; p53; Corticotropin-releasing hormone; ERK;
Neuromedin U causes biphasic cardiovascular effects and impairs baroreflex function in rostral ventrolateral medulla of spontaneously hypertensive rat by Ahmed A. Rahman; Israt Z. Shahid; Paul M. Pilowsky (15-24).
Neuromedin U (NMU) causes biphasic cardiovascular and sympathetic responses and attenuates adaptive reflexes in the rostral ventrolateral medulla (RVLM) and spinal cord in normotensive animal. However, the role of NMU in the pathogenesis of hypertension is unknown. The effect of NMU on baseline cardiorespiratory variables in the RVLM and spinal cord were investigated in urethane-anaesthetized, vagotomized and artificially ventilated male spontaneously hypertensive rats (SHR) and Wistar–Kyoto rats (WKY). Experiments were also conducted to determine the effects of NMU on somatosympathetic and baroreceptor reflexes in the RVLM of SHR and WKY. NMU injected into the RVLM and spinal cord elicited biphasic response, a brief pressor and sympathoexcitatory response followed by a prolonged depressor and sympathoinhibitory response in both hypertensive and normotensive rat models. The pressor, sympathoexcitatory and sympathoinhibitory responses evoked by NMU were exaggerated in SHR. Phrenic nerve amplitude was also increased following intrathecal or microinjection of NMU into the RVLM of both strains. NMU injection into the RVLM attenuated the somatosympathetic reflex in both SHR and WKY. Baroreflex sensitivity was impaired in SHR at baseline and further impaired following NMU injection into the RVLM. NMU did not affect baroreflex activity in WKY. The present study provides functional evidence that NMU can have an important effect on the cardiovascular and reflex responses that are integrated in the RVLM and spinal cord. A role for NMU in the development and maintenance of essential hypertension remains to be determined.
Keywords: Sympathetic vasomotor tone; Phrenic nerve activity; Somatosympathetic reflex; Spinal cord;
Fetal betamethasone exposure attenuates angiotensin-(1-7)-Mas receptor expression in the dorsal medulla of adult sheep by Allyson C. Marshall; Hossam A. Shaltout; Manisha Nautiyal; James C. Rose; Mark C. Chappell; Debra I. Diz (25-31).
Glucocorticoids including betamethasone (BM) are routinely administered to women entering into early preterm labor to facilitate fetal lung development and decrease infant mortality; however, fetal steroid exposure may lead to deleterious long term consequences. In a sheep model of fetal programming, BM-exposed (BMX) offspring exhibit elevated mean arterial pressure (MAP) and decreased baroreflex sensitivity (BRS) for control of heart rate by 0.5-years of age associated with changes in the circulating and renal renin-angiotensin systems (RAS). In the brain solitary tract nucleus, angiotensin (Ang) II actions through the AT1 receptor oppose the beneficial actions of Ang-(1-7) at the Mas receptor for BRS regulation. Therefore, we examined Ang peptides, angiotensinogen (Aogen), and receptor expression in this brain region of exposed and control offspring of 0.5- and 1.8-years of age. Mas protein expression was significantly lower (>40%) in the dorsal medulla of BMX animals at both ages; however, AT1 receptor expression was not changed. BMX offspring exhibited a higher ratio of Ang II to Ang-(1-7) (2.30 ± 0.36 versus 0.99 ± 0.28; p < 0.01) and Ang II to Ang I at 0.5-years. Although total Aogen was unchanged, Ang I-intact Aogen was lower in 0.5-year BMX animals (0.78 ± 0.06 vs. 1.94 ± 0.41; p < 0.05) suggesting a greater degree of enzymatic processing of the precursor protein in exposed animals. We conclude that in utero BM exposure promotes an imbalance in the central RAS pathways of Ang II and Ang-(1-7) that may contribute to the elevated MAP and lower BRS in this model.
Keywords: Fetal programming; RENIN angiotensin system; Brain; Sheep; Hypertension;
Melanin concentrating hormone induces hippocampal acetylcholine release via the medial septum in rats by Zhi-hong Lu; Satoru Fukuda; Yoichi Minakawa; Atsushi Yasuda; Hidetoshi Sakamoto; Shigehito Sawamura; Hidenori Takahashi; Noriko Ishii (32-39).
Among various actions of melanin concentrating hormone (MCH), its memory function has been focused in animal studies. Although MCH neurons project to various areas in the brain, one main target site of MCH is hippocampal formation for memory consolidation. Recent immunohistochemical study shows that MCH neurons directly project to the hippocampal formation and may indirectly affect the hippocampus through the medial septum nucleus (MS). It has been reported that sleep is necessary for memory and that hippocampal acetylcholine (ACh) release is indispensable for memory consolidation. However, there is no report how MCH actually influences the hippocampal ACh effluxes in accordance with the sleep–wake cycle changes. Thus, we investigated the modulatory function of intracerebroventricular (icv) injection of MCH on the sleep–wake cycle and ACh release using microdialysis techniques. Icv injection of MCH significantly increased the rapid eye movement (REM) and non-REM episode time and the hippocampal, not cortical, ACh effluxes. There was a significant correlation between REM episode time and hippocampal ACh effluxes, but not between REM episode time and cortical ACh effluxes. Microinjection of MCH into the MS increased the hippocampal ACh effluxes with no influence on the REM episode time. It appears that the effect sites of icv MCH for prolongation of REM episode time may be other neuronal areas than the cholinergic neurons in the MS. We conclude that MCH actually increases the hippocampal ACh release at least in part through the MS in rats.
Keywords: Acetylcholine; Hippocampus; Melanin concentrating hormone; Microdialysis; Rapid eye movement sleep;
Potency optimization of Huwentoxin-IV on hNav 1.7: A neurotoxin TTX-S sodium-channel antagonist from the venom of the Chinese bird-eating spider Selenocosmia huwena by Jefferson D. Revell; Per-Eric Lund; John E. Linley; Jacky Metcalfe; Nicole Burmeister; Sudharsan Sridharan; Clare Jones; Lutz Jermutus; Maria A. Bednarek (40-46).
The spider venom peptide Huwentoxin-IV (HwTx-IV) 1 is a potent antagonist of hNav1.7 (IC50 determined herein as 17 ± 2 nM). Nav1.7 is a voltage-gated sodium channel involved in the generation and conduction of neuropathic and nociceptive pain signals. We prepared a number of HwTx-IV analogs as part of a structure–function study into Nav1.7 antagonism. The inhibitory potency of these analogs was determined by automated electrophysiology and is reported herein. In particular, the native residues Glu1, Glu4, Phe6 and Tyr33 were revealed as important activity modulators and several peptides bearing mutations in these positions showed significantly increased potency on hNav1.7 while maintaining the original selectivity profile of the wild-type peptide 1 on hNav1.5. Peptide 47 (Gly1, Gly4, Trp33-HwTx) demonstrated the largest potency increase on hNav1.7 (IC50 0.4 ± 0.1 nM).
Keywords: Huwentoxin-IV; Nav1.7; Neuropathic; Nociceptive; Spider toxin; Synthetic peptide; Voltage-gated sodium channel;
Exercise reduces angiotensin II responses in rat femoral veins by Agnaldo Bruno Chies; Patrícia de Souza Rossignoli; Rafaela de Fátima Ferreira Baptista; Roger William de Lábio; Spencer Luiz Marques Payão (47-54).
► Angiotensin II responses are discrete in femoral veins. ► Discrete angiotensin II responses in femoral veins may assure the venous return. ► Angiotensin II responses in femoral veins are modulated by nitric oxide. ► Exercise mobilizes prostanoids to blunt the angiotensin II responses in femoral veins. ► Exercise mobilizes endothelin-1 to modulate angiotensin II responses in femoral veins.The control of blood flow during exercise involves different mechanisms, one of which is the activation of the renin-angiotensin system, which contributes to exercise-induced blood flow redistribution. Moreover, although angiotensin II (Ang II) is considered a potent venoconstrictor agonist, little is known about its effects on the venous bed during exercise. Therefore, the present study aimed to assess the Ang II responses in the femoral vein taken from sedentary and trained rats at rest or subjected to a single bout of exercise immediately before organ bath experiments. Isolated preparations of femoral veins taken from resting-sedentary, exercised-sedentary, resting-trained and exercised-trained animals were studied in an organ bath. In parallel, the mRNA expression of prepro-endothelin-1 (ppET-1), as well as the ETA and ETB receptors, was quantified by real-time PCR in this tissue. The results show that, in the presence of L-NAME, Ang II responses in resting-sedentary animals were higher compared to the other groups. However, this difference disappeared after co-treatment with indomethacin, BQ-123 or BQ-788. Moreover, exercise reduced ppET-1 mRNA expression. These reductions in mRNA expression were more evident in resting-trained animals. In conclusion, either acute or repeated exercise adapts the rat femoral veins, thereby reducing the Ang II responses. This adaptation is masked by the action of locally produced nitric oxide and involves, at least partially, the ETB- mediated release of vasodilator prostanoids. Reductions in endothelin-1 production may also be involved in these exercise-induced modifications of Ang II responses in the femoral vein.
Keywords: Angiotensin II; Endothelin; Exercise; Nitric oxide; Prostanoids; Vein;
Galanin receptors possibly modulate the obesity-induced change in pain threshold by Mei Yu; Penghua Fang; Mingyi Shi; Yan Zhu; Yong Sun; Qing Li; Ping Bo; Zhenwen Zhang (55-59).
► Galanin levels are enhanced during obesity and injury. ► Galanin regulates pain threshold via galanin receptors system. ► Galanin may increase the obese-induced pain threshold.Pain threshold may be up-regulated or down-regulated according to gender, age, race/ethnic and psychological state. Previous studies indicated that obesity may change pain threshold, both nociceptive and antinociceptive, which resulted from obesity-reduced variation of neuroendocrine. However there is a limited understanding of its molecular mechanism underlying this variation. A lot of evidence supports that galanin increases food intake and body weight to induce obesity in animals. This peptide may also modulate nociceptive susceptibility via central galanin receptor 1 and peripheral galanin receptor 2 in dorsal root ganglion. Whereas injury and obesity may up-regulate the galanin expression and stimulate its secretion to elevate the plasma levels of subjects. Pain may increase the risk of obesity through reduced physical activity. In this review, we highlighted the multiple bilateral interrelation between obesity and pain sensitivity, between galanin and obesity and between galanin and injure-induced pain. In view of the above, we reasoned that galanin receptors possibly participated in the modulation of the obesity-induced change in pain threshold, which need further direct evidence to support as yet. This review is helpful to explore the mechanism that galanin receptors regulate the obesity-induced change of pain sensitivity and to contribute to our understanding of the relation among galanin, obesity and pain threshold.
Keywords: Galanin receptor; Pain threshold; Obesity;
The effect of ghrelin on MK-801 induced memory impairment in rats by Fatemeh Goshadrou; Mojtaba Kermani; Abdolaziz Ronaghi; Samad Sajjadi (60-65).
Accumulating evidence indicates that the brain-gut peptide ghrelin which is expressed in hippocampus improves memory and learning processes. The MK-801, a noncompetitive NMDA receptor antagonist, has also shown amnesic properties in animal model. The current study was to find out whether intracerebroventricular administration of ghrelin can prevent amnesia induced by MK-801 in rats. A week after the surgery, during which cannuals were implanted in the lateral ventricular, the animals were trained and tested in a step-through type passive avoidance task. Memory retrieval was measured by step-through latency (STL) and total time in dark compartments (TDC). In the first series of experiments, we established a dose–response relationship for ghrelin on the passive avoidance paradigm. In the second set of experiments, animals were divided to two groups. In the first group, MK-801 (0.075, 0.15 and 0.3 mg/kg) was injected intraperitoneally (i.p.) immediately after the acquisition session and in the second group MK-801 (same doses) was injected (i.p.) 30 min before the retention session. Analysis of data showed that in both groups, MK-801 impaired learning and memory. In the third set of experiments, administration of ghrelin (200 ng/rat) right after the acquisition session (i.e. before MK-801 injection) improved the MK-801 induced memory impairment, but administration of ghrelin before retrieval session did not affect the MK-801 induced memory impairment.These results show an interaction between ghrelin and glutamatergic system. A novel finding in this study is that ghrelin can prevent amnesia produced by NMDA antagonist in rats when injected in post-training phase.
Keywords: Ghrelin; NMDA receptor antagonist; MK-801; Memory; Passive avoidance task;
Orexigenic effects of omentin-1 related to decreased CART and CRH gene expression and increased norepinephrine synthesis and release in the hypothalamus by Luigi Brunetti; Giustino Orlando; Claudio Ferrante; Lucia Recinella; Sheila Leone; Annalisa Chiavaroli; Chiara Di Nisio; Rugia Shohreh; Fabio Manippa; Adriana Ricciuti; Michele Vacca (66-74).
Omentin-1, a visceral fat depot-specific secretory protein, is inversely correlated with obesity and insulin resistance. We investigated, in rats, the effects of chronic omentin-1 administration (8 μg/kg, intraperitoneally, once daily for 14-days) on feeding behavior and related hypothalamic peptides and neurotransmitters. Food intake and body weight were recorded daily throughout the study. We found a significantly increased food intake compared to controls, but only in days 10–14, while body weight significantly increased since day 12 (P < 0.05). Compared with vehicle, omentin-1 treatment led to a significant reduction in both cocaine and amphetamine-regulated transcript (CART) (P < 0.05) and corticotrophin releasing hormone (CRH) (P < 0.05) gene expression, while pro-opiomelanocortin (POMC), agouti-related peptide (AgRP), neuropeptide Y (NPY) and orexin-A gene expression were not modified with respect to vehicle-treated rats. We also found an increase in hypothalamic levodopa (l-dopa) (P < 0.05) and norepinephrine (NE) (P < 0.01) synthesis, without any effect on dopamine (DA) and serotonin (5-hydroxytryptamine, 5-HT) metabolism. Furthermore, in hypothalamic synaptosomes, omentin-1 (10–100 ng/ml) stimulated basal NE release (ANOVA, P < 0.0001; post hoc, P < 0.001 vs. vehicle), in a dose-dependent manner, leaving unaffected both basal and depolarization-induced DA and 5-HT release. Finally, when synaptosomes were co-perfused with leptin and omentin-1, we observed that leptin was able to reverse omentin-1-induced stimulation of NE. In conclusion, the orexigenic effects of omentin-1 could be related, at least in part, to decreased CART and CRH gene expression and increased NE synthesis and release in the hypothalamus.
Keywords: Omentin-1; Appetite; Cocaine- and amphetamine-regulated transcript; Corticotrophin releasing hormone; Leptin; Norepinephrine;
Glucagon-like peptides 1 and 2 in health and disease: A review by Chinmay S. Marathe; Christopher K. Rayner; Karen L. Jones; Michael Horowitz (75-86).
► GLP-1, GLP-2 and glucagon share a common precursor but have divergent functions. ► A complex inter-dependent relationship exists between GLP-1 secretion, postprandial glycemia and gastric emptying. ► GLP-1 agonists retard gastric emptying. ► GLP-1 could be exploited therapeutically for its extra-intestinal effects. ► GLP-2 shows promise as an intestinotropic agent.The gut derived peptides, glucagon-like peptides 1 and 2 (GLP-1 and GLP-2), are secreted following nutrient ingestion. GLP-1 and another gut peptide, glucose-dependent insulinotropic polypeptide (GIP) are collectively referred to as ‘incretin’ hormones, and play an important role in glucose homeostasis. Incretin secretion shares a complex interdependent relationship with both postprandial glycemia and the rate of gastric emptying. GLP-1 based therapies are now well established in the management of type 2 diabetes, while recent literature has suggested potential applications to treat obesity and protect against cardiovascular and neurological disease. The mechanism of action of GLP-2 is not well understood, but it shows promise as an intestinotropic agent.
Keywords: Glucagon-like peptides; Postprandial glycemia; Incretin secretion; Gastric emptying;
Regulation of feeding behavior, gastrointestinal function and fluid homeostasis by apelin by Shuang-Yu Lv; Yan-Jie Yang; Qiang Chen (87-92).
Apelin was first identified and characterized from bovine stomach extracts as an endogenous ligand for the APJ receptor. Apelin/APJ system is abundantly present in peripheral tissues and central nervous system. Apelin plays a broad role in regulating physiological and pathological functions. Recently, many reports have showed the effects of apelin on feeding behavior, however the results are inconsistent, due to different administration routes, animal species, forms of apelin, etc. Apelin has been involved in stimulating gastric cell proliferation, cholecystokinin (CCK) secretion, histamine release, gastric acid and bicarbonate secretion, and regulation of gastrointestinal motility. In addition, apelin produced regulatory effects on drinking behavior, diuresis, arginine vasopressin (AVP) release and glucocorticoids secretion. This article reviews the role of apelin on feeding behavior, gastrointestinal function and fluid homeostasis.
Keywords: Apelin; APJ; Feeding behavior; Fluid homeostasis; Gastrointestinal function;
Characterization of novel 3′untranslated regions and related polymorphisms of the gene NPPC, encoding for the C-type natriuretic peptide by O. Melaiu; M.S. Facioni; M. Cabiati; R. Caruso; D. Giannessi; S. Landi; F. Gemignani; S. Del Ry (93-99).
Elevated plasmatic levels of C-type natriuretic peptide (CNP) were found in patients with chronic heart failure (CHF), but its use as sensitive and specific clinical bio-marker is still controversial. In fact, high levels of CNP were also observed in patients classified in low severity New York Heart Association (NYHA) classes. CNP is encoded by a gene poorly studied (NPPC, natriuretic-precursor peptide C), where the regulatory regions are not well defined and the role of single nucleotide polymorphisms (SNPs) poorly ascertained. In the present work, we focused on the characterization of the 3′untranslated region (3′UTR) of the gene, using Rapid Amplification of cDNA 3′-End (3′ RACE), and we identified two novel transcript isoforms (L-3′UTR; S-3′UTR; accession number JF420840, HQ419060 respectively). Since it could be hypothesized that genetic variations could explain the observed inter-patients differences, we searched for novel SNPs, by the use of High Resolution Melting (HRM). The results showed a complete lack of genetic variations among our series of samples. Moreover, a preliminary evaluation, using literature information and bioinformatic prediction allowed us to predicted the putative relevant microRNAs binding to the novel 3′UTRs that could modulate the post-transcriptional regulation of NPPC and affect the plasmatic levels of CNP. We obtained 750 and 1024 predicted miRNAs targeting the S- and L-3′UTRs, respectively.
Keywords: C-type natriuretic peptide; Heart failure; Genetic variations; 3′ untranslated region; Gene regulation;
Bradykinin B1 antagonism inhibits oxidative stress and restores Na+K+ ATPase activity in diabetic rat peripheral nervous system by Orlando Catanzaro; Jorgelina Aria Capponi; Jose Michieli; Emilio Labal; Irene Di Martino; Pierre Sirois (100-104).
► Diabetes induced hyperglycemia and reduced Na+K+ ATPase in rat sciatic nerve. ► MDA was elevated whereas BAP, GSH and SOD were decreased. ► BKB1 antagonist R-954 restored neuronal activity and reduced oxidative stress. ► BKB1-R is expressed in sciatic nerve as evidenced by inhibitory effects of R-954. ► The beneficial role of R-954 for diabetic neuropathy is suggested.Diabetic peripheral neuropathy is one the most common complications of diabetes mellitus and frequently results in clinically significant morbidities such as pain, foot ulcers and amputations. The diabetic condition progresses from early functional changes to late, poorly reversible structural changes. The chronic hyperglycemia measured alongside diabetes development is associated with significant damage and failure of various organs. In the present study diabetes was induced in male Wistar rats by a single dose of streptozotocin (STZ) and the association between the BKB1-R and the oxidative stress and Na+-K+ ATPase activity in nervous tissues was analysed. The results showed that the resulting hyperglycemia induced a reduction of the neuronal electrical function integrity and increased oxidative stress in the sciatic nerve homogenates of 30 days diabetic rats. Malondialdehyde (MDA) used as a marker of oxidative stress was elevated whereas Biological Antioxidant Potential (BAP), glutathion (GSH) levels and superoxide dismutase (SOD) activity were decreased. Treatment of the rats 3 days before the end of the 4 week period with the BKB1 antagonist R-954 restored the neuronal activity and significantly attenuated the oxidative stress as shown by the level of the various markers returning close to levels found in control rats. Our results suggest that the BKB1-R subtype is overexpressed in sciatic nerve during the STZ-induced diabetes development as evidenced by inhibitory effects of the BKB1-R antagonist R-954. The beneficial role of BKB1-R antagonist R-954 for the treatment of diabetic neuropathy is also suggested.
Keywords: Diabetes; Sciatic nerve; GSH; BAP; SOD; MDA; Na+/K+ ATPase; Bradykinin B1 receptor antagonist; R-954;
Synergistic analgesic effects between neuronostatin and morphine at the supraspinal level by Shao-Bin Yang; Ai-Min Yang; Ting-Ji Shao; Shu-Fang Su; Qiang Chen (105-110).
Neuronostatin, a 13-amino acid peptide, is encoded in the somatostatin pro-hormone. I.c.v. administration of neuronostatin produces a significant antinociceptive effect in the mouse tail-flick test, which is mediated by endogenous opioid receptor. However, the direct functional interaction between morphine and neuronostatin has not been characterized. In the present study, effect of neuronostatin on morphine analgesia was investigated in the tail-flick test. Our findings showed that i.c.v. administration of neuronostatin (0.3 nmol/mouse i.c.v.) significantly enhanced the antinociceptive effect of morphine (2.5, 5 or 10 μg/kg) at the supraspinal level. Results of antagonism experiments suggested that the synergistic analgesia induced by morphine and neuronostatin was mediated by μ- and к-opioid receptors not δ-opioid receptor. In conclusion, there may be a cascade amplification phenomenon when morphine and neuronostatin were co-administered in acute pain model. The above results provide evidence for the potential use of neuronostatin in combination with morphine to control pain and addiction.
Keywords: Neuronostatin; Morphine; Opioid receptors; Synergistic analgesia; Mice;
Angiotensin II-mediated vascular changes in aged offspring rats exposed to perinatal nicotine by Hehua Tao; Can Rui; Jianli Zheng; Jiaqi Tang; Lei Wu; Aiping Shi; Ningjing Chen; Rui He; Chonglong Wu; Jiayue Li; Xiaohui Yin; Peiwen Zhang; Zhoufeng Zhu; Jianying Tao; Jianping Xiao; Caiping Mao; Zhice Xu (111-119).
► Prenatal nicotine affects vessel health in the aged offspring rats. ► The aged female offspring was not free of vascular risks. ► Affected RAS mediated vascular changes.This study determined the long-term influence of prenatal nicotine exposure (PN) on blood pressure and vascular functions in the aged offspring rats. PN did not affect body weight and plasma adrenocorticotropic hormone level; however, it significantly reduced plasma angiotensin I and angiotensin II in both sexes. Systolic pressure in the male aged PN offspring was significantly higher. Angiotensin II-increased mean arterial pressure was higher in the aged PN offspring than that in the control regardless of sex. AT1 receptor blocker losartan, not AT2 receptor antagonist PD123319, reduced blood pressure in the aged PN rats more than that in the control. In the aged PN offspring, angiotensin II-increased vessel contraction and intracellular calcium level were higher in small mesenteric arteries. Acetylcholine-mediated vascular relaxation was weaker, and nitric oxide-related endothelial functions were damaged in aortic rings of PN offspring. Thickness of the wall of mesenteric arteries was increased in the male aged PN offspring. Ratio of AT1/AT2 receptors was significantly increased in the vessel of the PN group regardless of sex. These data provide new information on the very long term influence of PN on vascular structures and functions in the aged offspring, demonstrate that the aged PN female rats were not free of vascular risks after menopause, and suggest that multiple pathways may be involved in the detrimental alterations of the cardiovascular system of the PN rats.
Keywords: Nicotine; Angiotensin; Vascular functions; Aged offspring; Gender;
Protective effect of β-casomorphin-7 on cardiomyopathy of streptozotocin-induced diabetic rats via inhibition of hyperglycemia and oxidative stress by Dong-Ning Han; Dong-Hui Zhang; Li-Ping Wang; Yuan-Shu Zhang (120-126).
β-Casomorphin-7 (β-CM-7) is regarded as the most representative milk-derived bioactive peptide. The present work studies the efficacy of β-CM-7 against myocardial injury in streptozotocin-induced diabetic rats, focusing on the following assays: (1) the level of blood glucose and advanced glycosylation end product (AGE), the activity of lactate dehydrogenase (LDH) in serum; (2) the level of hydrogen peroxide (H2O2), the activity of Na+K+-ATPase, Ca2+Mg2+-ATPase and enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) in myocardial tissue; (3) the protein expression of glucose transporter-4 (GLUT-4) in myocardial tissue. It showed that with the influence of β-CM-7, the levels of blood glucose of β-CM-7 treatment group decreased markedly compared with model group (P < 0.01) accompanied with their alleviated symptoms of diabetes. In the antioxidant and oxidant levels, β-CM-7 treatment group signified a remarkable increase in the activity of GSH-Px, SOD and CAT of the anti-oxidation system and meanwhile demonstrated a considerable reduction in H2O2 content (all P < 0.05) in comparison with model group. We also found both the content of AGE and the activity of LDH of β-CM-7 treated group considerably reduced while the content of GLUT-4 and the activity of Na+K+-ATPase and Ca2+Mg2+-ATPase of β-CM-7 treated group increased obviously (P < 0.05). Meanwhile the cardiac indexes were significantly lessened. Thus our assay validates that the remedy employing β-CM-7 may treat diabetic cardiomyopathy with high efficacy predominantly associated with the mechanism that β-CM-7 ameliorates myocardial energy metabolism and abates free-radical-mediated oxidative stress in blood and myocardium.
Keywords: β-Casomorphin-7; Diabetic cardiomyopathy; Oxidative stress; Glucose metabolism;
Designer peptide antagonist of the leptin receptor with peripheral antineoplastic activity by Serena Beccari; Ilona Kovalszky; John D. Wade; Laszlo Otvos; Eva Surmacz (127-134).
The obesity hormone leptin has been implicated in the development and progression of different cancer types, and preclinical studies suggest that targeting leptin signaling could be a new therapeutic option for the treatment of cancer, especially in obese patients. To inhibit pro-neoplastic leptin activity, we developed leptin receptor (ObR) peptide antagonists capable of blocking leptin effects in vitro and in vivo. Our lead compound (Allo-aca), however, crosses the blood–brain-barrier (BBB), inducing undesirable orexigenic effects and consequent weight gain. Thus, redesigning Allo-aca to uncouple its central and peripheral activities should produce a superior compound for cancer treatment. The aim of this study was to generate novel Allo-aca analogs and test their biodistribution in vivo and anti-neoplastic activity in vitro in breast and colorectal cancer cells. Examination of several Allo-aca analogs resulted in the identification of the peptidomimetic, d-Ser, that distributed only in the periphery of experimental animals. d-Ser inhibited leptin-dependent-proliferation of ObR-positive breast and colorectal cancer cells in vitro at 1 nM concentration without exhibiting any partial agonistic activity. d-Ser efficacy was demonstrated in monolayer and three-dimensional cultures, and its antiproliferative action was associated with the inhibition of several leptin-induced pathways, including JAK/STAT3, MAPK/ERK1/2 and PI3K/AKT, cyclin D1, and E-cadherin. In conclusion, d-Ser is the first leptin-based peptidomimetic featuring peripheral ObR antagonistic activity. The novel peptide may serve as a prototype to develop new therapeutics, particularly for the management of obesity-related cancers.
Keywords: Antagonist peptide; Blood–brain barrier; Cancer; Leptin receptor; Peripheral activity;
Neuropeptides in sepsis: From brain pathology to systemic inflammation by Fabiano Pinheiro da Silva; Marcel Cerqueira César Machado; Irineu Tadeu Velasco (135-138).
Septic encephalopathy is frequently diagnosed in critically ill patients and in up to 70% of patients with severe systemic infection . The syndrome is defined by diffuse cerebral dysfunction or structural abnormalities attributed to the effects of systemic infection, rather than a direct central nervous system cause. The clinical characteristics can range from mild delirium to deep coma, but patients are often medically sedated making the diagnosis difficult. Any manifestation, however, is specific and markers of disease are lacking . Sepsis survivors present long term cognitive impairment, including alterations of memory, attention and concentration [10,54]. Here, we propose that neuropeptides may play a key role in septic encephalopathy, leading to a vicious circle characterized by brain disease and systemic inflammation.
Keywords: Sepsis; Encephalopathy; Neuropeptides;
Truncated antimicrobial peptides from marine organisms retain anticancer activity and antibacterial activity against multidrug-resistant Staphylococcus aureus by Ming-Ching Lin; Cho-Fat Hui; Jyh-Yih Chen; Jen-Leih Wu (139-148).
Antimicrobial peptides (AMPs) were recently determined to be potential candidates for treating drug-resistant bacterial infections. The aim of this study was to develop shorter AMP fragments that combine maximal bactericidal effect with minimal synthesis cost. We first synthesized a series of truncated forms of AMPs (anti-lipopolysaccharide factor from shrimp, epinecidin from grouper, and pardaxin from Pardachirus marmoratus). The minimum inhibitory concentrations (MICs) of modified AMPs against ten bacterial species were determined. We also examined the synergy between peptide and non-peptide antibiotics. In addition, we measured the inhibitory rate of cancer cells treated with AMPs by MTS assay. We found that two modified antibacterial peptides (epinecidin-8 and pardaxin-6) had a broad range of action against both gram-positive and gram-negative bacteria. Furthermore, epinecidin and pardaxin were demonstrated to have high antibacterial and anticancer activities, and both AMPs resulted in a significant synergistic improvement in the potencies of streptomycin and kanamycin against methicillin-resistant Staphylococcus aureus. Neither AMP induced significant hemolysis at their MICs. In addition, both AMPs inhibited human epithelial carcinoma (HeLa) and fibrosarcoma (HT-1080) cell growth. The functions of these truncated AMPs were similar to those of their full-length equivalents. In conclusion, we have successfully identified shorter, inexpensive fragments with maximal bactericidal activity. This study also provides an excellent basis for the investigation of potential synergies between peptide and non-peptide antibiotics, for a broad range of antimicrobial and anticancer activities.
Keywords: Antimicrobial peptides; Epinecidin-1; Pardaxin-1; SALF; Antimicrobial; Anticancer;
The pro-apoptotic action of new analogs of the insect gonadoinhibiting peptide Neb-colloostatin: Synthesis and structure–activity studies by Mariola Kuczer; Elżbieta Czarniewska; Grzegorz Rosiński; Marek Lisowski (149-157).
Neb-colloostatin (SIVPLGLPVPIGPIVVGPR), an insect oostatic factor found in the ovaries of the flesh fly Neobellieria bullata, strongly induces apoptosis in insect haemocytes. To explain the role of Ser1 and Pro4 residues of Neb-colloostatin in the pro-apoptotic activity of this peptide, the synthesis of a series of analogs was performed, such as: [Ac-Ser1]- (1), [d-Ser1]- (2), [Thr1]- (3), [Asp1]- (4), [Glu1]- (5), [Gln1]- (6), [Ala1]- (7), [Val1]- (8), [d-Pro4]-(9), [Hyp4]- (10), [Acp4]- (11), [Ach4]- (12), [Ala4]- (13), [Ile4]- (14), and [Val4]-colloostatin (15). All peptides were bioassayed in vivo for the pro-apoptotic action on haemocytes of Tenebrio molitor. Additionally, the structural properties of Neb-colloostatin and its analogs were examined by the circular dichroism in water and methanol. Peptides 1, 4, 5, 7, 8, 10, 12, 14, and 15 strongly induce T. molitor haemocytes to undergo apoptosis and they show about 120–230% of the Neb-colloostatin activity at a dose of 1 nM. The CD conformational studies show that the investigated peptides seem to prefer the unordered conformation.
Keywords: Neb-colloostatin; Apoptosis; Haemocyte; Insect peptide; Haemocytotropic activity;
Role of α-CGRP in the regulation of neurotoxic responses induced by kainic acid in mice by Soo-Hyun Park; Yun-Beom Sim; Chea-Ha Kim; Jin-Koo Lee; Jong-Ho Lee; Hong-Won Suh (158-162).
Kainic acid (KA) is an excitatory and neurotoxic substance. The role of α-calcitonin gene-related peptide (α-CGRP) in the regulation of KA-induced hippocampal neuronal cell death was investigated in the present study. The intracerebroventricular (i.c.v.) administration with KA (0.07 μg) increased hippocampal α-CGRP mRNA level in ICR mice. The α-CGRP mRNA level began to increase at 1 h, reached at maximal level at 6 and 12 h, and returned to the control level by 24 h after i.c.v. administration with KA. In addition, KA-induced hippocampal CA3 neuronal death in C57BL6 (wild type) group was more pronounced compared to KA-induced hippocampal CA3 pyramidal cell death in α-CGRP knock-out (KO) group. Furthermore, sumatriptan, a CGRP releasing inhibitor, significantly protected the pyramidal cell death in CA3 hippocampal region induced by KA administered i.c.v. in ICR mice. Our results suggest that α-CGRP may play an important role in the regulation of KA-induced pyramidal cell death in CA3 region of the hippocampus.
Keywords: Kainic acid; Cell death; α-CGRP; Hippocampus;
Theoretical structural insights into the snakin/GASA family by William F. Porto; Octavio L. Franco (163-167).
Among the main classes of cysteine-stabilized antimicrobial peptides, the snakin/GASA family has not yet had any structural characterization. Through the combination of ab initio and comparative modeling with a disulfide bond predictor, the three-dimensional structure prediction of snakin-1 is reported here. The structure was composed of two long α-helices with a disulfide pattern of CysI-CysIX, CysII-CysVII, CysIII-CysIV, CysV-CysXI, CysVI-CysXII and CysVIII-CysX. The overall structure was maintained throughout molecular dynamics simulation. Snakin-1 showed a small degree of structural similarity with thionins and α-helical hairpins. This is the first report of snakin-1 structural characterization, shedding some light on the snakin/GASA family.