Peptides (v.23, #5)
Cicerin and arietin, novel chickpea peptides with different antifungal potencies by X.Y Ye; T.B Ng; P.F Rao (817-822).
Two antifungal peptides with novel N-terminal sequences, designated cicerin and arietin were isolated from seeds of the chickpea (Cicer arietinum), respectively. Both peptides were adsorbed on Affi-gel blue gel and CM-Sepharose and exhibited a molecular weight of approximately 8.2 and 5.6 kDa, respectively. Arietin was more strongly adsorbed on CM-Sepharose than cicerin and manifested a higher translation-inhibiting activity in a rabbit reticulocyte lysate system and a higher antifungal potency toward Mycosphaerella arachidicola, Fusarium oxysporum and Botrytis cinerea. Both were devoid of mitogenic and anti-HIV-1 reverse transcriptase activities.
Keywords: Chickpea; Antifungal peptides;
The immunosuppressive activity of peptide fragments of vaccinia virus C10L protein and a hypothesis on the role of this protein in the viral invasion by Alicja Kluczyk; Ignacy Z Siemion; Zbigniew Szewczuk; Zbigniew Wieczorek (823-834).
Our previous studies revealed that the 143–148 fragment of interleukin-1 receptor antagonist (IL-1 Ra) molecule with a Val–Thr–Lys–Phe–Tyr–Phe (VTKFYF) sequence inhibits the interleukin-1 (IL-1) interaction with its cellular receptor. The Val–Thr–Arg–Phe–Tyr–Phe (VTRFYF) sequence of the 322–327 fragment of the C-terminal domain of vaccinia virus protein related to the C10L vaccinia gene shows a very high homology to the 143–148 IL-1 Ra fragment, suggesting a similar inhibitory activity. To test this suggestion, we investigated the inhibitory activity of a series of synthetic peptides derived from 316 to 327 fragment of C10L on the interaction of IL-1 with its receptor. We also tested the peptides for their influence on the humoral and cellular immune response. The results indicate that biological activities of the C10L fragments are similar to those obtained for respective fragments of IL-1 Ra. The C-terminal domain of C10L protein can be easily folded into spatial structure similar to the crystallographic one of IL-1 Ra. Based on the crystallographic structure of IL-1 Ra, we constructed a 3-D model of the C10L protein. According to the model, the Val322–Asn328 sequence is localized on the surface of the molecule and, therefore, it may be involved in the interactions with receptors. Our results indicate that the C10L viral protein can play an important role in vaccinia virus evasion of the host immune system. It may consist in the blockade of IL-1 receptors by the C10L protein, a homologue of the IL-1 Ra.
Keywords: Vaccinia virus C10L protein; Interleukin-1; Thymopentin analogs; Immunosuppressors; CD4; Virtual protein folding;
Effects of opiate ligands on intraspecific aggression in crickets by Varya Dyakonova; F.-W Schürmann; D.A Sakharov (835-841).
In the cricket Gryllus bimaculatus, the opiate antagonist naloxone, 30 μg in 50 μl into hemolymph per animal, caused a release of intraspecific aggression in male-losers and in females. Naloxone had no significant effect on the aggression of winners and isolated males. The agonist of μ-opiate receptors DAGO, 45 μg, suppressed aggression in male winners and decreased the percentage and duration of contact fights between previously isolated males. The results suggest that, during social contacts, the activity of the endogenous opioid system may contribute to suppressing aggression in subordinate males, as well as in females.
Keywords: Naloxone; μ-Opiate receptors; DAGO; Aggression; Insect; Gryllus bimaculatus;
Potent antagonistic action of synthetic analogues of APGWGNamide, an antagonist of molluscan neuropeptide APGWamide by M. Ohtani; H. Minakata; S. Aimoto (843-852).
Fifty-five kinds of analogues of APGWGNamide (Ala–Pro–Gly–Trp–Gly–Asn–NH2), which is an antagonist of molluscan neuropeptide APGWamide, were synthesized and their antagonistic activities were examined on two molluscan smooth muscles. Among all the analogues tested, on spontaneous contraction of the crop of the land snail, Euhadra congenita, APGWG(l-biphenylalanine, Bip)amide showed the most potent antagonistic activity and its potency was 50–100 times higher than that of APGWGNamide. Likewise, on phasic contraction of the anterior byssus retractor muscle (ABRM) of the sea mussel, Mytilus edulis, the effect of APGWG(d-homophenylalanine, dHfe) was the most potent and showed 5–10 times stronger activity than that of APGWGNamide. In the tolerance test to known exo- and endopeptidases or the crop tissue homogenate, APGWGNamide was not only easily degraded by a proline-specific endopeptidase but also by the homogenate. Two kinds of potent antagonists were thus developed: APGWG(Bip)amide and APGWG(dHfe)amide, which will be useful tools for investigation of the function of APGWamide in the snail and the mussel, respectively.
Keywords: Antagonist; APGWamide; APGWGNamide; Peptidase; Potent analogue; Unnatural amino acid;
Antipeptide antibodies for detecting crab (Callinectes sapidus) molt-inhibiting hormone by Kara J. Lee; R.Douglas Watson (853-862).
In crustaceans, the synthesis of ecdysteroid molting hormones is regulated by molt-inhibiting hormone (MIH), a neuropeptide produced by an eyestalk neuroendocrine system, the X-organ/sinus gland complex. Using sequence analysis software, two regions of the blue crab (Callinectes sapidus) MIH peptide were selected for antibody production. Two 14-mer peptides were commercially synthesized and used to generate polyclonal antisera. Western blot analysis revealed that each antiserum bound to proteins of the predicted size in extracts of C. sapidus sinus glands, and lysates of insect cells containing recombinant MIH. Thin section immunocytochemistry using either antiserum showed specific immunoreactivity in X-organ neurosecretory cell bodies, their associated axons and collaterals, and their axon terminals in the sinus gland.
Keywords: Molt-inhibiting hormone; MIH; Antipeptide antibodies; Callinectes sapidus; Bombyxin;
Enzymatic activity of soluble and membrane tethered peptide pro-hormone convertase 1 by Angela Bruzzaniti; Richard E Mains (863-875).
Pro-hormone convertases PC1 and PC2 perform endoproteolytic cleavages of precursors in peptide-containing secretory granules. PC1 and PC2 are soluble, secreted with bioactive peptides. Evolutionarily related PCs have membrane tethers, not secreted. We tethered PC1 to the transmembrane-cytoplasmic domains (CD) of a granule enzyme (peptidylglycine-α-amidating monooxygenase; PAM) and Golgi-localized PC8. The tethered PC1 is far more stable to elevated temperature and denaturants than soluble PC1, and more active. Both tethers allow PC1 to visit the cell surface transiently, cleaving soluble molecules outside the cell. Both membrane-bound PC1 chimeras cleave membrane PAM into soluble active fragments when PAM is expressed on adjacent cells.
Effects of MCH/NEI in the striatum and interactions between them and with α-MSH on IP3 levels by Mónica Silvina Sanchez; Victoria Berberian; Marı́a Ester Celis (877-880).
In this study, we investigated: (a) the effect of melanocyte concentrating hormone (MCH) and neuropeptide glutamine (E)-isoleusine-(I) (NEI) on IP3 production on an “in vitro” model using slices containing caudate putamen (CP) and accumbens nuclei (ACC); and (b) the interaction between these peptides and with α-melanocyte-stimulating-hormone (α-MSH) on the production of this second messenger. Only MCH at the highest dose studied (3.6 μM) increased the production of IP3, whereas at the low concentration (0.6 μM) it did not affect IP3 levels. NEI and α-MSH at both concentrations tested (0.6 and 3.6 μM), did not affect IP3 production either. However, when NEI or α-MSH (at 3.6 μM) were added together with 3.6 μM MCH, the increase in the IP3 content induced by this last peptide was blocked.
Keywords: IP3; α-MSH; MCH; NEI; Striatum; Brain slices;
Differential responsiveness of CRF receptor subtypes to N-terminal truncation of peptidic ligands by Olaf Brauns; Simone Brauns; Bodo Zimmermann; Olaf Jahn; Joachim Spiess (881-888).
The role of the N-terminal domains of corticotropin-releasing factor (CRF) and CRF-like peptides in receptor subtype selectivity, ligand affinity and biological potency was investigated. Therefore, human CRF12–41, human URP12–38 and antisauvagine-30 (aSvg) were N-terminally prolonged by consecutive addition of one or two amino acids. The peptides obtained were tested for their binding affinities to rat CRF1 and murine CRF2β receptor, and their capability to stimulate cAMP-release by HEK cells producing either receptor.It was observed that human CRF N-terminally truncated by eight residues was bound with high affinity to CRF2 receptor (K i =5.4 nM), whereas affinity for CRF1 receptor was decreased (K i =250 nM). A similar shift of affinity was found with sauvagine (Svg) analogs. Truncation of human URP analogs did not affect their preference for CRF2β receptor, but reduced their affinity. Changes in affinity were positively correlated with changes in potency. These results indicated that CRF1 receptor was more stringent in its structural requirements for ligands to exhibit high affinity binding than CRF2β receptor.
Keywords: Sauvagine; Antisauvagine; CRF; Urocortin II; Urocortin-related peptide; CRF receptor;
μ-Opioid receptor mRNA expression and immunohistochemical localization in the rat temporomandibular joint by Katsuhiko Hayashi; Masashi Sugisaiki; Shuji Ota; Haruyasu Tanabe (889-893).
This study was undertaken to examine the presence and distribution of the μ-opioid receptor (MOR) in the non-inflamed rat temporomandibular joint (TMJ) using non-radiographic in situ hybridization at the mRNA level and immunohistochemistry at the protein level. MOR mRNA and MOR-like immunoreactivity (MOR-LI) were found around the small blood vessels in the anterior part of the synovial membrane. The number of MOR mRNA signals in the anterior synovial membrane was significantly higher than that in the posterior part. Morphologically, MOR mRNA and MOR-LI were localized in amorphous materials considered to be nervous tissue, as well as some cell types considered to be macrophages, mast cells and endothelial cells. The present study showed the distribution of MOR in the rat TMJ synovial membrane and suggests that the opiate system plays an important role in endogenous analgesia in the TMJ.
Keywords: μ-Opioid receptor; Temporomandibular joint; Rat; In situ hybridization; Immunohistochemistry;
Differential antagonism of endomorphin-1 and endomorphin-2 supraspinal antinociception by naloxonazine and 3-methylnaltrexone by Shinobu Sakurada; Takafumi Hayashi; Masayuki Yuhki; Tsutomu Fujimura; Kimie Murayama; Akihiko Yonezawa; Chikai Sakurada; Mitsuhiro Takeshita; Takumi Sato; James E Zadina; Abba J Kastin; Tsukasa Sakurada (895-901).
To determine if different subtypes of μ-opioid receptors were involved in antinociception induced by endomorphin-1 and endomorphin-2, the effect of pretreatment with various μ-opioid receptor antagonists β-funaltrexamine, naloxonazine and 3-methylnaltrexone on the inhibition of the paw-withdrawal induced by endomorphin-1 and endomorphin-2 given intracerebroventricularly (i.c.v.) were studied in ddY male mice. The inhibition of the paw-withdrawal induced by i.c.v. administration of endomorphin-1, endomorphin-2 or DAMGO was completely blocked by the pretreatment with a selective μ-opioid receptor antagonist β-funaltrexamine (40 mg/kg), indicating that the antinociception induced by all these peptides are mediated by the stimulation of μ-opioid receptors. However, naloxonazine, a μ1-opioid receptor antagonist pretreated s.c. for 24 h was more effective in blocking the antinociception induced by endomorphin-2, than by endomorphin-1 or DAMGO given i.c.v. Pretreatment with a selective morphine-6β-glucuronide blocker 3-methylnaltrexone 0.25 mg/kg given s.c. for 25 min or co-administration of 3-methylnaltrexone 2.5 ng given i.c.v. effectively attenuated the antinociception induced by endomorphin-2 given i.c.v. and co-administration of 3-methylnaltrexone shifted the dose–response curves for endomorphin-2 induced antinociception to the right by 4-fold. The administration of 3-methylnaltrexone did not affect the antinociception induced by endomorphin-1 or DAMGO given i.c.v. Our results indicate that the antinociception induced by endomorphin-2 is mediated by the stimulation of subtypes of μ-opioid receptor, which is different from that of μ-opioid receptor subtype stimulation by endomorphin-1 and DAMGO.
Keywords: Naloxonazine; β-Funaltrexamine; 3-Methylnaltrexone; Endomorphin-1; Endomorphin-2;
Family of hemorphins: co-relations between amino acid sequences and effects in cell cultures by Elena Y Blishchenko; Olga V Sazonova; Olga A Kalinina; Oleg N Yatskin; Marina M Philippova; Andrei Y Surovoy; Andrei A Karelin; Vadim T Ivanov (903-910).
Hemorphins, i.e. endogenous fragments of β-globin chain segment (32–41) LVVYPWTQRY(F) suppress the growth of transformed murine fibroblasts L929 cell culture, the effect is due to cytotoxicity and inhibition of cell proliferation. The contribution of cytotoxicity depends on the presence of Leu32: VV-hemorphins, except VV-hemorphin-4, exhibit cytotoxicity significantly higher than respective LVV-hemorphins. Decrease of cell number induced by hemorphins depend on the extent of N- and C-terminal degradation of hemorphins: VV-hemorphins in most cases are more active than LVV-, V-hemorphins, and hemorphins. In the group of VV-hemorphins the activity of VV-hemorphin-5 (valorphin) is significantly higher than of VV-hemorphin-7, VV-hemorphin-6, and VV-hemorphin-4, meaning that the presence of C-terminal Gln is important for suppressing of cell number. The amino acid sequence VVYPWTQ corresponding to valorphin was identified as important for manifestation of the both cytotoxic and antiproliferative effects.
Keywords: Hemorphin; Proliferation; Cytotoxicity;
β-Endorphin modulation of pressor response to hyperventilation in hypertensive patients by Fiorella Fontana; Pasquale Bernardi; Santi Spampinato; Rosanna Di Toro; Raffaele Bugiardini (911-918).
After hyperventilation, systolic and diastolic blood pressure (BP) significantly decreased in 14 hypertensive patients (group 1), did not change in 9 (group 2) and increased in 8 (group 3). Basal BP, norepinephrine and dynorphin B levels were higher in group 1 than in groups 2 and 3. The decrease in BP after hyperventilation was associated with a decrease in plasma norepinephrine, Met-enkephalin and dynorphin B and an increase in β-endorphin. Naloxone abolished the hyperventilation-induced BP and norepinephrine decreases. Our findings indicate that hyperventilation may select hypertensive patients with different sympatho-adrenergic activity and that the increase in β-endorphin reduces BP response to hyperventilation in patients with high sympatho-adrenergic tone.
Keywords: Hyperventilation; β-Endorphin; Dynorphin B; Met-enkephalin; Naloxone; Norepinephrine; Hypertensive patients;
Tobacco smoke exposure and bombesin-like peptides in guinea pigs by Dale R Bergren (919-926).
Bombesin-like peptides (BLPs) are associated with tobacco smoke (TS)-induced diseases. We sought to determine if acute TS exposure releases BLPs into the pulmonary circulation. Sensitized and non-sensitized guinea pigs were chronically exposed to TS or compressed air. Thereafter, the lungs were acutely challenged with TS while perfused. Perfusates were analyzed for BLPs. TS increased BLPs in non-sensitized guinea pigs. A separate study determined daily bombesin exposure increased lung cell counts but not airway hyperresponsivensess. TS exposure releases BLPs into the pulmonary circulation but can be modified by host factors and bombesin itself does not induce airway hyperresponsiveness.
Keywords: Bombesin; Gastrin-releasing peptides; Ovalbumin-sensitized guinea pigs; Neuroendocrine cells; Lung perfusion; Plethysmography;
Neuropeptide Y Y1 and neuropeptide Y Y2 receptors in human cardiovascular tissues by Rolf Uddman; Sebastian Möller; Torun Nilsson; Susanne Nyström; Jonas Ekstrand; Lars Edvinsson (927-934).
mRNA encoding the human NPY Y1 and NPY Y2 receptors were detected in cerebral, meningeal, and coronary arteries using reverse transcriptase–polymerase chain reaction (RT–PCR). In addition, the trigeminal and superior cervical ganglia were positive for both receptors. In some arteries and in SK-N-MC cells only mRNA encoding the NPY Y1 was detected. Besides the expected NPY Y1 PCR products, an additional 97 bp longer amplicon originating from an alternative splicing event was found in most tissues studied. Antibodies directed against the NPY Y1 receptor revealed immunostaining mainly in the smooth muscle layer of blood vessels whereas antibodies against the NPY Y2 receptor showed immunostaining in nerve cell bodies.
Keywords: Neuropeptide Y receptors; Autonomic nervous system; Blood vessels; RT–PCR;
Human bone marrow endothelial cells: a new identified source of B-type natriuretic peptide by Laurence Bordenave; Agnès Georges; Reine Bareille; Véronique Conrad; Franck Villars; Joelle Amédée (935-940).
B-type natriuretic peptide (BNP) is a hormone mainly secreted by cardiac ventricle myocytes and which is increased in cardiac diseases. Moreover, BNP expression has been shown in various cell/tissue types. Six different human endothelial cell (EC) culture models arising from macro and microcirculation either primary cultures or cell lines were cultured and screened for BNP presence and secretion. All cell types expressed BNP mRNA while only the ECs arising from bone marrow stromal compartment secreted high amounts of BNP protein. This report is the first to identify ECs as a new source of BNP. However, BNP secretion is limited to a particular EC type.
Keywords: Endothelium; B-type natriuretic peptide; Cell culture;
Age differences in neurokinin A and substance P from the hypothalamus, pituitary, pineal gland, and striatum of the rat by C Fernández; L Debeljuk; E Dı́az; B Dı́az (941-945).
Previous data showed that aging of the central nervous system (CNS) is associated with widespread changes in tachykinin gene expression. However, there are no data about the possible role of exogenous melatonin in modulating the tachykinergic system during aging. The aim of this work was to analyze the age-dependent changes on neurokinin A (NKA) and substance P (SP) levels in hypothalamus, pituitary, pineal gland and striatum and the role of exogenous melatonin on these changes. We studied female rats at three different ages: 5-month-old (cyclic), 15-month-old (preacyclic) and 25-month-old (acyclic). Hypothalamic tachykinin levels increase when female rats reached acyclicity, this increase was blunted in acyclic-melatonin-treated rats. However, melatonin treatment in young cyclic rats resulted in significantly increased values as compared to controls. Pituitary NKA concentrations did no show age-dependent changes in control rats, however, in both, preacyclic and acyclic-melatonin-treated rats significantly increased values of pituitary NKA were found compared to controls. In the pineal gland, a marked decrease of NKA levels was observed in acyclic-control rats. Melatonin treatment did not alter this decrease. In the striatum, NKA and SP concentrations were significantly reduced in preacyclic- and acyclic-control rats compared to young cyclic rats, melatonin had no effect on striatal tachykinins. Our results indicate that melatonin may regulate tachykinin stores during aging mainly on structures of the neuroendocrine–reproductive axis.
Keywords: NKA; SP; Aging; Melatonin;
Selective tachykinin NK3-receptor agonists stimulate in vitro exocrine pancreatic secretion in the guinea pig by G Linari; M Broccardo; V Nucerito; G Improta (947-953).
The tachykinins, including substance P, neurokinin A and neurokinin B, are a mammalian peptide family that have documented motor, sensory and circulatory neurotransmitter functions in the gut. Little is known about their action on the exocrine pancreas. In this study we investigated the effects of PG-KII, a natural NK3-tachykinin receptor agonist, and senktide, a synthetic NK3-tachykinin receptor agonist, on amylase release from isolated pancreatic lobules of the guinea pig in comparison with the secretagogues carbachol, caerulein and substance P and the depolarizing agent KCl. When added to incubation flasks at various concentrations (from 10−10 to 10−6 M), PG-KII and senktide both caused a dose-dependent increase in amylase release from pancreatic lobules. PG-KII and senktide elicited a lower maximal response (7.5±0.8 and 8.1±0.6% of the total lobular amylase content) than carbachol (34.4±3.9%), caerulein (26.5±2.8%) and KCl (22.5±3.8%). Whereas atropine left PG-KII and senktide-stimulated secretion unaffected, the non peptide NK3 receptor antagonist SR 142801 significantly reduced the stimulant effect of PG-KII and senktide. PG-KII (10−7 M) also slightly though significantly increased the response to lower concentrations of caerulein (10−11 and 10−10 M) and carbachol (10−7 and 10−6 M). These findings show that PG-KII and senktide are weak stimulants of exocrine pancreatic secretion that act directly on the acinar cells through NK3 receptors, without cholinergic involvement. We suggest also that the tachykininergic NK3 receptor system cooperates with the other known secretagogues in the control of pancreatic exocrine secretion.
Keywords: Tachykinin NK3-receptor agonists; Pancreatic lobules; Amylase release; Guinea pig;
Localization of calcitonin gene-related peptide receptors in rat gastric mucosa by Kousaku Kawashima; Shunji Ishihara; Mohammad Azharul Karim Rumi; Nobuyuki Moriyama; Hideaki Kazumori; Hiroshi Suetsugu; Hiroshi Sato; Ryo Fukuda; Kyoichi Adachi; Masahiro Shibata; Sadayoshi Onodera; Tsutomu Chiba; Yoshikazu Kinoshita (955-966).
The location of calcitonin gene-related peptide (CGRP) receptors in the rat stomach has not been elucidated. It was recently reported that the CGRP receptor is formed when a calcitonin-receptor-like receptor (CRLR) and receptor activity modifying protein (RAMP) 1 are co-expressed on the cell membrane. The aim of this study was to determine the location and the role of CGRP receptors in the rat gastric mucosa. Gene expressions of CRLR and RAMP1 were investigated by Northern blot analysis, reverse transcription-polymerase chain reaction (RT-PCR), and in situ hybridization. Immunohistochemical stainings for CGRP, somatostatin, gastrin, and chromogranin A were performed. Gastric endocrine cells were collected by counterflow-elutriation and their responses to CGRP were studied. CRLR and RAMP1 mRNA was expressed mainly in small gastric epithelial cells in the pyloric glands. The mRNA expression had a similar distribution to that of D cells. In cultured gastric endocrine cells, CGRP enhanced somatostatin production, while it inhibited the secretion of histamine and gastrin. Our results suggest that CGRP receptors are expressed in D cells in the rat gastric mucosa and control production and secretion of somatostatin.
Keywords: Calcitonin-receptor-like receptor; D cell; Somatostatin; Receptor activity modifying protein;
Anxiolytic-like effects of substance P fragment (SP1–7) in non-human primates (Callithrix penicillata) by Marilia Barros; M.A De Souza Silva; Joseph P Huston; Carlos Tomaz (967-973).
The behavioral effects of the amino (N)-terminal fragment of substance P (SP1–7) on the marmoset (Callithrix penicillata) predator confrontation test of fear/anxiety were investigated. The test apparatus consisted of a figure-eight maze with three parallel arms interconnected at each extremity to a perpendicular arm. A taxidermized oncilla cat (Felis tigrina) was placed outside the maze facing one of its corners. Subjects were submitted to seven 30 min maze habituation trials (HTs), in the absence of the ‘predator’, and then to six 30 min treatment trials (TTs), in the presence of the ‘predator’, consisting of four doses of SP1–7 (5, 50, 250 and 500 μg/kg; IP), saline and sham injection. SP1–7 treatment reversed, in a dose-dependent way, the fear-induced avoidance behavior due to the predator’s presence and increased the frequency of exploratory behaviors. Locomotor activity decreased during successive HTs, yet increased after all SP1–7 treatments. These results indicate that systemic administration of SP1–7 produces anxiolytic-like effects in marmosets tested in the predator confrontation model of fear/anxiety.
Keywords: Substance P; N-terminal fragment; Anxiolytic effect; Marmoset; Predator confrontation test;
Central LIF gene therapy suppresses food intake, body weight, serum leptin and insulin for extended periods by Elena Beretta; Harveen Dhillon; Pushpa S Kalra; Satya P Kalra (975-984).
Leukemia inhibitory factor (LIF) overexpression, induced by the intracerebroventricular (i.c.v.) injection of an recombinant adeno-associated viral vector encoding LIF (rAAV–LIF), resulted in a dose-dependent reduction in body weight (BW) gain, food intake (FI) and adiposity, evidenced by suppression of serum leptin and free fatty acids for an extended period in outbred adult female rats. A dose-dependent reduction in serum insulin levels and unchanged serum glucose, energy expenditure through thermogenesis as indicated by uncoupling protein-1 (UCP-1) mRNA expression in brown adipose tissue (BAT), and metabolism as indicated by serum T3 and T4, accompanied the blockade of weight gain. Thus, central rAAV–LIF therapy is a viable strategy to voluntarily reduce appetite and circumvent leptin resistance, a primary factor underlying age-dependent weight gain and obesity in rodents and humans.
Keywords: Leukemia inhibitory factor; rAAV; Gene therapy; Food intake; Obesity; Leptin; Insulin; Glucose;
Acute 3rd-ventricular amylin infusion potently reduces food intake but does not produce aversive consequences by Paul A Rushing; Randy J Seeley; Ellen L Air; Thomas A Lutz; Stephen C Woods (985-988).
In this study, a conditioned taste aversion (CTA) paradigm was used to assess the possibility that 3rd-ventricular (i3vt) administration of the pancreatic hormone amylin produces aversive consequences that secondarily reduce food intake independently of the normal regulation of energy balance. After 1-h daily access to water for 7 days, rats were given 1-h access to a 0.15% saccharin solution, followed immediately by i3vt amylin (100 pmol) in one group (n=7) and i3vt CSF vehicle in another (n=7). As positive control for the formation of a CTA, a third group of seven rats received intraperitonial (i.p.) lithium chloride (LiCl). Saline was given i.p. to a fourth group (n=7) as control for i.p. LiCl. As expected, the LiCl rats exhibited a marked aversion to the saccharin in a subsequent two-bottle intake test. In contrast, although the 100 pmol i3vt amylin dose is substantially higher than that required to reduce food intake, no evidence of a CTA was observed in the rats that had received i3vt amylin. In summary, these data are consistent with the conclusion that acute i3vt amylin infusion does not reduce food intake by producing aversive consequences.
Keywords: Islet amyloid polypeptide; Hormone; Ingestion; Rat;
Specificity and stability of a new PTH1 receptor antagonist, mouse TIP(7–39) by Sam R.J Hoare; Ted B Usdin (989-998).
Parathyroid hormone 1 (PTH1) receptor antagonists might be of benefit in hypercalcemia of malignancy (HHM) and hyperparathyroidism. We previously identified bovine tuberoinfundibular peptide (7–39) (bTIP(7–39)) as a high-affinity PTH1 receptor antagonist. Mouse TIP(7–39) is an antagonist (rPTH1 K B=44 nM, rPTH2=940 nM) that is more potent than other known PTH1 receptor antagonists: bTIP(7–39) (210 nM), PTH-related protein (PTHrP)(7–34) (640 nM), and bPTH(7–34) (>3000 nM). Plasma proteases slowly (t 1/2=81 min) inactivated [ 125 I ]mTIP(7–39). Intravenous plasma [ 125 I ]mTIP(7–39) was bi-phasically cleared (radioactivity t 1/2=2.9 min (70%) and 120 min (30%), binding activity t 1/2=3.6 min (92%), and t 1/2=21 min (8%)). Loss of unlabeled mTIP(7–39) (250 μg/kg i.v.) receptor binding was similar. mTIP(7–39)’s high-affinity should facilitate animal evaluation of effects of PTH1 receptor antagonism.
Keywords: Hypercalcemia; Parathyroid hormone; Tuberoinfundibular peptide; Hyperparathyroidism; Plasma pharmacokinetics;
Role of SA–Lea and E-selectin in metastasis assessed with peptide antagonist by Insug O; Laszlo Otvos; Thomas Kieber-Emmons; Magdalena Blaszczyk-Thurin (999-1010).
E-selectin ligand Sialyl–Lewis a (SA–Lea) carbohydrate is expressed on many carcinomas. Peptide mimicking SA–Lea (DLWDWVVGKPAG) was previously selected from a recombinant library by screening with monoclonal antibody (MAb) NS19-9. In this study, the residues critical for interaction with the NS19-9 were mapped using peptide array generated by substitution of various amino acid residues. The replacement of Trp 5 with Phe resulted in a change of peptide’s secondary structure and increased binding with MAb and E-selectin, suggesting improved carbohydrate mimicry. Colonization of tumor cells expressing SA–Lea was blocked by the peptide and was completely abolished in E-selectin knock out mice. The data suggest the critical role of carbohydrate antigens and E-selectin in metastasis and that peptides mimicking carbohydrate antigens can function as antagonists of this process.
Keywords: Carbohydrate structure; Sialyl–Lewis a; Peptide mimics; E-selectin; Tumor metastasis;
Thymosin α1 inhibits mammary carcinogenesis in Fisher rats by Terry W Moody; Cynthia Tuthill; Mahnaz Badamchian; Allan L Goldstein (1011-1014).
The effects of thymosin α1 (Tα1) on mammary carcinogenesis was investigated in Fisher rats. Mammary carcinomas were observed 3 months after N-nitrosomethylurea (NMU) injection (10 mg, i.p.) into Fisher rats. Daily administration of Tα1 (10 μg, s.c.) reduced mammary carcinoma incidence and prolonged survival time. Animals treated with exogenous Tα1 had a significantly greater blood white cell density than control Fisher rats. These results suggest that Tα1 prevents mammary carcinoma incidence as a result of stimulation of the immune system.
Keywords: Thymosin α1; Mammary carcinoma; Chemoprevention; Fisher rats;
In vitro effect of short-term exposure to two synthetic peptides, alone or in combination with clarithromycin or rifabutin, on Cryptosporidium parvum infectivity by Andrea Giacometti; Oscar Cirioni; Wojciech Kamysz; Franciszek Kasprzykowski; Francesco Barchiesi; Maria Simona Del Prete; Zbigniew Maćkiewicz; Giorgio Scalise (1015-1018).
The viability of Cryptosporidium parvum after exposure to peptide antibiotics was studied by two different methods, a cell culture system and a double fluorogenic staining. The peptides KFFKFFKFF and IKFLKFLKFL exerted high cytotoxic effects on sporozoites, as demonstrated by cell cultures (complete inhibition after 60 min at 100 μg/ml) and flow cytometry (30% after 20 min at 100 μg/ml), but did not affect consistently the oocysts. Clarithromycin and rifabutin demonstrated less activity against sporozoites but higher activity against oocysts (30% after 180 min at 10 μg/ml). The combination between peptides and azithromycin or rifabutin exerted the highest activities.
Keywords: Cryptosporidium parvum; Peptides; In vitro susceptibility;