Peptides (v.26, #5)

Anti-alopecia mechanisms of soymetide-4, an immunostimulating peptide derived from soy β-conglycinin by Takahiro Tsuruki; Kyoya Takahata; Masaaki Yoshikawa (707-711).
Previously, we found that orally administered soymetide-4 (MITL), an immunostimulating peptide derived from soybean β-conglycinin α′ subunit, suppressed alopecia induced by the anti-cancer drug etoposide in neonatal rats. Soymetide-4 has weak affinity for N-formyl-methionyl-leucyl-phenylalanine (fMLP) receptor. fMLP showed an anti-alopecia effect after intraperitoneal administration, though it was inactive after oral administration. Anti-alopecia effect of fMLP was blocked by pyrilamine or cimetidine, antagonists for histamine H1 or H2 receptor, respectively. However, the anti-alopecia effect of soymetide-4 was not inhibited by the histamine antagonists but by indomethacin, an inhibitor of cyclooxygenase (COX), or AH-23848B, an antagonist of the EP4 receptor for PGE2. Anti-alopecia effect of soymetide-4 was also blocked by pyrrolidine dithiocarbamate, an inhibitor of nuclear factor-κB (NF-κB). These results suggest that PGE2, which is produced after activation of COX by soymetide-4, might suppress apoptosis of hair matrix cells and etoposide-induced alopecia by activating NF-κB.
Keywords: Alopecia; Etoposide; Peptide; Prostaglandin; Soybean;

New antibacterial peptide derived from bovine hemoglobin by Rachid Daoud; Veronique Dubois; Loredana Bors-Dodita; Naima Nedjar-Arroume; Francois Krier; Nour-Eddine Chihib; Patrice Mary; Mostafa Kouach; Gilbert Briand; Didier Guillochon (713-719).
Peptic digestion of bovine hemoglobin at low degree of hydrolysis yields an intermediate peptide fraction exhibiting antibacterial activity against Micrococcus luteus A270, Listeria innocua, Escherichia coli and Salmonella enteritidis after separation by reversed-phase HPLC. From this fraction a pure peptide was isolated and analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). This peptide correspond to the 107–136 fragment of the α chain of bovine hemoglobin. The minimum inhibitory concentrations (MIC) towards the four strains and its hemolytic activity towards bovine erythrocytes were determined. A MIC of 38 μM was reported against L. innocua and 76 μM for other various bacterial species. This peptide had no hemolytic activity up to 380 μM concentration.
Keywords: Antibacterial peptide; Bovine hemoglobin; Pepsin; Active peptide; Hydrolysate;

Design and expression of peptide antibiotic hPAB-β as tandem multimers in Escherichia coli by Xiancai Rao; Jinchuan Hu; Shu Li; Xiaolin Jin; Chun Zhang; Yanguang Cong; Xiaomei Hu; Yinling Tan; Jianjun Huang; Zijin Chen; Junming Zhu; Fuquan Hu (721-729).
Peptide antibiotics are small peptides encoded by organism genomic DNA. They are recognized to play important roles in the innate host defense of most living organisms. The growing resistance of bacteria to conventional antibiotics and the need for discovery of new antibiotics have stimulated great interest in the development of peptide antibiotics as human therapeutics. However, preparation of peptide antibiotics at a large scale is a great challenge in developing these commercial products. In this study, tandem repeat multimers of peptide antibiotic hPAB-β were designed and the recombinant plasmids containing one to eight copies of hPAB-β gene were generated. Eight genetic engineered bacteria harboring pQE-hPAB-β1–8 recombinant were able to express the repetitive hPAB-β multimers of interest in inclusion bodies, respectively. The expressed proteins could reach 2.6–28% of the total proteins. The hPAB-β trimer construct was selected out for the subsequent study based on its higher expression level (27.8%), which yields in wet cell weights (3.15 ± 0.45 g/l) and the fusion protein inclusion bodies was able to completely dissolve in 8 M urea. The tandem trimers could easily be captured by Ni-NTA affinity chromatography and cleaved into monomers by hydroxylamine. Then, the monomer hPAB-β of interest was purified to 95% homogeneity by reverse phase chromatography and gel filtration. The final yield of purified recombinant monomer hPAB-β was 680 ± 12 mg/100 g wet cells. The minimum inhibitory concentrations (MICs) of the purified recombinant hPAB-β against type or clinical strains of microorganisms were about 31–250 μg/ml and these results showed that the recombinant hPAB-β could retain its bioactivity.
Keywords: Peptide antibiotic hPAB-β; Tandem repetitive multimers; Expression; Bioactivity;

Scorpion venoms are a particularly rich source of neurotoxic proteins/peptides that interact in a highly specific fashion with discrete subtypes of ion channels in excitable and non-excitable cells. Here we have employed a recently developed technique to effect molecular cloning and structural characterization of a novel putative potassium channel-blocking toxin from the same sample of venom from the North African scorpion, Androctonus amoreuxi. The deduced precursor open-reading frame is composed of 59 amino acid residues that consists of a signal peptide of approximately 22 amino acid residues followed by a mature toxin of 37 amino acid residues. The mature toxin contains two functionally important residues (Lys27 and Tyr36), constituting a functional dyad motif that may be critical for potassium channel-blocking activity that can be affirmed from structural homologs as occurring in the venoms from other species of Androctonus scorpions. Parallel proteomic/transcriptomic studies can thus be performed on the same scorpion venom sample without sacrifice of the donor animal.
Keywords: Scorpion; Venom; Neurotoxin; Potassium channel; Molecular cloning;

Peptide Tyrosine Arginine, a potent immunomodulatory peptide isolated and structurally characterized from the skin secretions of the dusky gopher frog, Rana sevosa by Ciaren Graham; Alexandra E. Irvine; Stephen McClean; Stephen C. Richter; Peter R. Flatt; Chris Shaw (737-743).
An octadecapeptide was isolated from the skin secretions of the dusky gopher frog (Rana sevosa) on the basis of histamine release from rat peritoneal mast cells. This peptide was purified to homogeneity by HPLC and found to have the following primary structure, YLKGCWTKSYPPKPCFSR, using both Edman degradation chemistry and peptide sequencing using high-resolution mass spectrometry (Q-TOF MS). The peptide, named peptide Tyrosine Arginine (pYR) shares 77.8% homology with peptide Leucine Arginine (pLR). The effects of the natural amidated peptide, non-amidated peptide and C-loop region of pYR on granulopoiesis and neutrophil apoptosis were investigated. All three analogues inhibited the early development of granulocyte macrophage colonies from bone marrow stem cells but did not induce apoptosis of the end stage granulocytes, the mature neutrophil. Thus, pYR is a novel member of an important and emerging new class of amphibian peptides with hemopoietic actions.
Keywords: Granulopoiesis; Histamine; HPLC; Peptidomics; Rana sevosa; Skin secretions;

We identified cDNA coding for a homologue to mammalian leptin in puffer, Takifugu rubripes, using genomic synteny around the human leptin gene. In addition to significant sequence homologies, the puffer leptin (pLEP) displays characteristic structural features in common with mammalian leptin. The pLEP mRNA was expressed mostly in the liver that contained abundant lipids. In addition, homologues to pLEP were found in the databanks for three fish species (salmon, medaka, and Tetraodon) and two amphibians (salamander and Xenopus). The phylogenetic analysis shows rapid rates of molecular divergence among leptins from different vertebrate classes, but not between mammals and avians.
Keywords: Leptin; cDNA; Takifugu rubripes; Fish; Amphibian;

The role of previous exposure in the appetitive and consummatory effects of orexigenic neuropeptides by Stephen C. Benoit; Deborah J. Clegg; Stephen C. Woods; Randy J. Seeley (751-757).
The ingestion of foods is comprised of two distinct phases of behavior: appetitive and consummatory. While most food intake paradigms include both phases, the intraoral intake test emphasizes the stereotyped consummatory-phase by infusing a liquid food directly into the oral cavity. Several hypothalamic peptides have been shown to increase intake of chow in standard food intake paradigms and the current experiments sought to test whether these peptides would increase food intake in the intraoral intake paradigm. NPY, melanin-concentrating hormone (MCH) and orexin-A were infused into the third ventricle (i3vt) in a counterbalanced latin-square design just prior to rats getting 0.1 M sucrose solution infused via indwelling intraoral catheters and compared it to intake on bottle tests with access to the same sucrose solution. On the first day, each peptide increased intraoral intake relative to saline in the between-subjects comparison. Moreover, intake of sucrose following i3vt saline increased as a function of training. By the final day of the experiment, rats receiving saline consumed as much sucrose as rats receiving NPY, MCH, or orexin-A. This finding was conceptually replicated in the second experiment in which rats drank sucrose freely from a bottle on the home cage. A third experiment directly assessed the role of previous exposure in the sucrose intake induced by NPY. Those results confirm that repeated exposure to sucrose increases baseline intake and attenuates the hyperphagic effect of NPY. These results are consistent with two conclusions: (1) NPY, MCH, and orexin-A increase both appetitive and consummatory-phase ingestive behaviors on initial exposures; (2) repeated training interacts with the effects of these orexigenic peptides.
Keywords: Learning; Intraoral intake; MCH; Orexin-A;

Orexin-A-induced feeding is dependent on nitric oxide by Susan A. Farr; William A. Banks; Vijaya B. Kumar; John E. Morley (759-765).
Orexin-A is a peptide produced in the lateral hypothalamus/perifornical area, which stimulates feeding. The production of orexin-A is determined by the metabolic state of the animal. We have previously shown that nitric oxide (NO) plays an important role as a mediator of feeding induced by a variety of neuropeptides. This raises the question of whether orexin-A's effects are NO dependent. Here, we first determined that intracerebroventricular administration of 25 ng of orexin-A significantly increased food intake in satiated mice. We next examined the effects of N ω-nitro-l-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, on orexin-A-induced increase in food intake. L-NAME (50 mg/kg; SC) significantly blocked the orexin-A-induced increase in food intake. Orexin-A administration increased the levels of nitric oxide synthase in the hypothalamus. To further verify the importance of NO in the orexin-A-induced increase in food intake, we compared the ability of orexin-A to increase food intake in neuronal nitric oxide synthase knockout (NOS-KO) mice and their wild-type controls. Orexin-A failed to increase food intake in the NOS-KO mice, whereas it did increase food intake in the wild-type controls. This supports the hypothesis that nitric oxide is a central regulator of food consumption.
Keywords: Orexin-A; L-NAME; Mouse; Food intake; Nitric oxide; Orexigenic peptides; Hypothalamus;

Enhanced antinociception by intracerebroventricularly and intrathecally-administered orexin A and B (hypocretin-1 and -2) in mice by Jalal Izadi Mobarakeh; Kazuhiro Takahashi; Shinobu Sakurada; Seiji Nishino; Hiroyuki Watanabe; Motohisa Kato; Kazuhiko Yanai (767-777).
Orexins are neuropeptides located exclusively in neurons of the lateral hypothalamic area, which send projections to most monoaminergic nuclei, such as noradrenergic locus coeruleus, dopaminergic ventral tegmental areas, and histaminergic tuberomammillary nuclei. The present work was carried out to examine the role of orexins in nociception in mice. C57BL/6 mice were administered with orexin A and B intracerebroventricularly (i.c.v.), intrathecally (i.t.) and subcutaneously (s.c.) to reveal the sites of action of these peptides and to examine the pain thresholds using four kinds of nociceptive tasks. Orexins showed antinociceptive effects in all four types of assays for thermal (hot-plate, tail-flick, paw-withdrawal), mechanical (tail-pressure), chemical (formalin, capsaicin and abdominal stretch) nociceptions and nociceptin-induced behavioral responses, when administered i.c.v. or i.t., whereas the s.c. administration was ineffective. The antinociceptive effects of orexin A were more remarkable than those of orexin B. The i.c.v. administration of orexin A was as effective as, or more potent than the i.t. administration. The effects of orexin A were completely blocked by adenosine type 1 receptor antagonists, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) and theophylline, but not by naloxone, suggesting a possible involvement of the adenosine-containing neurons and/or the adenosine pathway in these orexin actions. The i.c.v. administration of nociceptin had no significant effects on orexin expression in the brain and spinal cord. The present findings suggest that orexins have an antinociceptive role in at least four different types of pains, probably acting on both the brain and spinal cord.
Keywords: Orexin; Pain perception; Nociception; C57BL/6 mouse; Intracerebroventricular; Intrathecal;

Structural studies on 26RFa, a novel human RFamide-related peptide with orexigenic activity by Romain Thuau; Laure Guilhaudis; Isabelle Ségalas-Milazzo; Nicolas Chartrel; Hassan Oulyadi; Stéphane Boivin; Alain Fournier; Jérôme Leprince; Daniel Davoust; Hubert Vaudry (779-789).
A novel hypothalamic neuropeptide of the RFamide family, comprising 26 amino acids residues and thus termed 26RFa, has been recently characterized in human, and was found to be the endogenous ligand for the orphan G protein-coupled receptor GPR103. Intracerebroventricular injection of 26RFa provokes a robust increase in food intake in rodents. In the present study, we have investigated the solution conformation of 26RFa by using two-dimensional NMR spectroscopy in different media. In water, 26RFa exhibits mainly a random coil conformation although the presence of a nascent helix was detected between residues 6 and 15. In methanol, 26RFa adopts a well-defined conformation consisting of an amphipathic α-helical structure (Pro4–Arg17), flanked by two N- and C-terminal disordered regions. The strong conservation, from amphibians to mammals, of the amino acid sequence corresponding to the amphipathic helix and to the C-terminal flexible octapeptide of 26RFa, suggests that these two domains are crucial for the interaction of the peptide with its receptor.
Keywords: RFamide-related peptide; Neuropeptide; 1H NMR; Molecular modeling; Solution structure;

Neuropeptide FF receptors exert contractile activity via inhibition of nitric oxide release in the mouse distal colon by Quan Fang; Jia Guo; Min Chang; Li-xiang Chen; Qiang Chen; Rui Wang (791-797).
Neuropeptide FF (NPFF) and NPVF, two closely NPFF related peptides, have different affinities for the two NPFF receptors (NPFF1 and NPFF2). To assess the peripheral effects of NPFF receptors in the gastrointestinal tract motility, NPFF and NPVF were tested in the mouse isolated distal colon. Both NPFF (1–15 μM) and NPVF (1–15 μM) dose-dependently caused significant colonic contractions. Pre-treatment with the putative NPFF antagonist, BIBP3226 (30 μM) abolished the contractile responses to the two neuropeptides (3 μM). They had no additional contractile activities in colonic preparations contracted by N ω-nitro- l-arginine (30 μM). Moreover, the contractions of these two neuropeptides were weakened by l-arginine (2 mM). The responses to NPFF (5 μM) and NPVF (5 μM) were not modified by atropine or naloxone (1 μM). Furthermore, NPFF (1 μM) and NPVF (1 μM) did not influence the contractive responses to acetylcholine (0.1–10 μM), morphine (1 μM) or nociceptin (0.1 μM). These data suggest that NPFF and NPVF cause contractions of the mouse distal colon via their NPFF receptors and this effect is mediated by NO but not by cholinergic pathways, independently from opioid system. In addition, the isolated bioassay may be applied as a simple parameter to characterize the potential NPFF agonists and antagonists.
Keywords: Neuropeptide FF (NPFF); NPVF; Mouse distal colon; BIBP3226; Nitric oxide (NO); Opioid;

Substance P and the neurokinin-1 receptor in relation to eosinophilia in ulcerative colitis by Maria Jönsson; Örjan Norrgård; Sture Forsgren (799-814).
Substance P (SP) has been implicated in the pathophysiology of ulcerative colitis (UC) and it has been suggested that blocking of its effect would be advantageous in this disease. Eosinophils have also been implicated in the pathophysiology of UC. In the present study, specimens from the sigmoid colon of UC patients were investigated by the use of antisera against SP and the neurokinin-1 receptor (NK-1R) and staining for demonstration of eosinophils. The degrees of SP innervation and NK-1R immunoreaction, as well as the levels of eosinophil infiltration, varied between different patients. Interestingly, NK-1R immunoreaction in the epithelium was often seen to be the most marked where there were numerous eosinophils in the underlying mucosa and where the mucosa showed a marked morphologic derangement. The observations suggest that there are marked fluctuations in effects of SP and eosinophils during the disease. The infiltrating eosinophils may be involved in the destruction of the mucosal tissue. Furthermore, for the majority of cases where there is marked derangement of the mucosa, it is apparent that there is an upregulation of the NK-1 receptor in the epithelium in parallel with the infiltration of the eosinophils.
Keywords: Ulcerative colitis; Neuropeptides; Substance P; Neurokinin-1 receptor; Eosinophils;

Expression of galanin receptor messenger RNAs in different regions of the rat gastrointestinal tract by Laura Anselmi; Alexander Lakhter; Arlene A. Hirano; Marcello Tonini; Catia Sternini (815-819).
Galanin effects are mediated by three G-protein-coupled receptors: galanin receptor 1 (GalR1), GalR2 and GalR3. We quantified mRNA levels of GalR1, GalR2 and GalR3 in the rat stomach, small and large intestine using real-time RT-PCR. All three GalR mRNAs were detected throughout the gut at different levels. GalR1 and GalR2 mRNA levels were higher in the large than in the small intestine. GalR2 mRNA was most abundant in the stomach. GalR3 mRNA levels were generally quite low. The differential regional distribution of GalRs suggests that the complex effects of galanin in the gut are the result of activating multiple receptor subtypes, whose density, subtype and signaling vary along the gastrointestinal tract.
Keywords: Real-time RT-PCR; Intestine; Stomach; Enteric nervous system;

Dexamethasone reverses the memory impairment induced by antagonism of hippocampal gastrin-releasing peptide receptors by Roberta Venturella; Daniela Lessa; Tatiana Luft; Benno Roozendaal; Gilberto Schwartsmann; Rafael Roesler (821-825).
Storage of emotionally influenced memory is regulated by activation of glucocorticoid receptors (GRs) as well as of gastrin-releasing peptide receptors (GRPRs) in the dorsal hippocampus. In the present study, male Wistar rats were given a bilateral infusion of saline or the GRPR antagonist (D-Tpi6, Leu13 psi[CH2NH]-Leu14) bombesin (6-14) (RC-3095) (1.0 μg/side) into the dorsal hippocampus 10 min before training on an inhibitory avoidance task, followed by an immediate post-training i.p. injection of vehicle or the GR agonist dexamethasone (0.3 mg/kg). A retention test trial, carried out 24 h after training, indicated that intrahippocampal infusion of RC-3095 impaired inhibitory avoidance retention. Post-training administration of dexamethasone induced an enhancement of retention regardless of whether the animals had received saline or RC-3095 into the hippocampus before training. The findings indicate that hippocampal GRPR blockade does not prevent memory enhancement induced by dexamethasone. Together with previous results, these findings suggest that endogenous activation of GRPRs in the hippocampus modulates the consolidation of emotional memory, but is not a critical receptor system mediating memory formation.
Keywords: RC-3095; Bombesin-like peptides; Gastrin-releasing peptide receptor; Glucocorticoids; Hippocampus; Memory modulation;

Brain mast cells and therapeutic potential of vasoactive intestinal peptide in a Parkinson's disease model in rats: Brain microdialysis, behavior, and microscopy by Neşe Tunçel; Erol Şener; Cem Cerit; Umut Karasu; Firdevs Gürer; Varol Şahintürk; Cengiz Bayçu; Dilek Ak; Zeynep Filiz (827-836).
In the present study, the effect of systemically administered vasoactive intestinal peptide (VIP) (25 ng/kg i.p.) was investigated on drug-induced rotational behavior, extra-cellular dopamine levels and histology of corpus striatum in a 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease. After 15 days of 6-OHDA lesion, apomorphine-induced (0.05 mg/kg s.c.) rotational behavior of the animals significantly increased and extra-cellular dopamine levels of corpus striatum were significantly reduced. VIP reversed the rotational deficits but did not alter the decrease in striatal dopamine levels. On the other hand, histological data indicate that VIP significantly reduced neuronal death and demyelination. Electron microscopic appearance of mast cells showed ultra-structural variety between VIP-treated and 6-OHDA lesioned groups. VIP activates mast cells without any evidence of typical exocytosis, and possibly mast cells could participate in neuroprotection. Our results suggest that systemically administered VIP can attenuate the motor response changes, neuronal cell death, and myelin sheet loss characteristically associated with 12 μg 6-OHDA administration into the rat striatum. Brain mast cells seem to participate in neuronal protection. Possibly, protective cues could be produced by brain mast cells.
Keywords: 6-OHDA toxicity; Corpus striatum; Dopamine; Rotational behavior;

The effects of neurotensin on selected parameters of lipid metabolism in rats by J. Piątek; H. Witmanowski; J. Paluszak; H. Krauss; J. Krawczyk (837-843).
15 nM/kg b.m. of neurotensin (NT) caused a significant inhibition of LMA within 30 min of administration and this effect persisted up for to the 240th minute of the experiment. A 15 nM/kg b.m. dose also caused a reduction in SLA which persisted up to the 120th minute. Sixty minutes after an intraperitoneal administration of NT a decrease in the cholesterol and NEFA levels and an increase in the TG and glycerol levels were observed. These effects were inhibited by the NTR2-blocker (levocabastine) and were not subject to change after an in vivo application of SR 48692.
Keywords: Neurotensin; Neurotensin receptors; Cholesterol; Lipid metabolism;

Effects of adipokines on expression of adrenomedullin and endothelin-1 in cultured vascular endothelial cells by Kazuhiro Takahashi; Kazuhito Totsune; Masahiko Sone; Kumi Kikuchi; Osamu Murakami (845-851).
Obesity is a major risk factor for the development of hypertension. Adipokines may cause hypertension by acting both centrally and directly on the vascular vessels. We wished to clarify whether three adipokines, leptin, resistin and tumor necrosis factor-α, affect expression of adrenomedullin and endothelin-1 in vascular endothelial cells. Human umbilical vein endothelial cells were cultured for 24 h with leptin (1–10 nmol/l), resistin (1–10 nmol/l) or tumor necrosis factor-α (1–10 ng/ml). Expression of adrenomedullin and endothelin-1 was examined by radioimmunoassay and northern blot analysis. Immunoreactive-adrenomedullin in the medium and adrenomedullin mRNA expression levels were decreased by treatment of tumor necrosis factor-α time- and dose-dependently, whereas endothelin-1 secretion was not significantly changed by it. Leptin or resistin had no significant effects on expression of adrenomedullin or endothelin-1 in human umbilical vein endothelial cells. Under hypoxic conditions (1% O2), expression of both adrenomedullin and endothelin-1 was induced in these cells. Immunoreactive-adrenomedullin levels in the medium were decreased by treatment of tumor necrosis factor-α under hypoxia. Leptin or resistin had no significant effects on adrenomedullin or endothelin-1 expression also in hypoxia. These findings have raised the possibility that decreased expression of adrenomedullin by tumor necrosis factor-α may be related to the increased risk of hypertension and other cardiovascular diseases in obese subjects.
Keywords: Adrenomedullin; Endothelin; Leptin; Resistin; Tumor necrosis factor; Adipokines; Obesity;

Carboxy-terminal PTH fragments stimulate [3H]thymidine incorporation in vascular endothelial cells by Ke-Hong Ding; Qing Zhong; Ding Xie; Jianrui Xu; Roni J. Bollag; Wendy B. Bollag; Carlos M. Isales (853-862).
We have previously reported that the intact PTH molecule (1–84) stimulates proliferation of human umbilical vein endothelial cells (HUVECs). To define the bioactive portion of the PTH molecule we utilized amino, mid and carboxy-terminal PTH fragments. Carboxy- but not amino-terminal fragments were equivalent to the intact PTH molecule in stimulating [3H]thymidine incorporation in HUVEC. Carboxy- but not amino-terminal PTH fragments increased intracellular calcium. Blocking the rise in intracellular calcium with calcium chelators abolished PTHs proliferative effect on HUVEC. In contrast to PTH 1–84, the carboxy-terminal fragment effect on [3H]thymidine incorporation was blocked by KN-93 an inhibitor of CaM kinase II. Taken together, these data suggest that the carboxy-terminal PTH is (or contains) the bioactive fragment responsible for the changes in intracellular calcium and thymidine incorporation in HUVEC stimulated with the intact PTH molecule.
Keywords: Endothelial cells; PTH; Proliferation; Signaling; Calcium; Receptors;

Ligand-dependent complex formation between the Angiotensin II receptor subtype AT2 and Na+/H+ exchanger NHE6 in mammalian cells by Lakshmi Pulakat; Shannon Cooper; Dieter Knowle; Chirag Mandavia; Steven Bruhl; Mary Hetrick; Nara Gavini (863-873).
Keywords: Angiotensin II; AT2 receptor; Na+/H+ exchanger; Human NHE6; Protein–protein interaction;

Substance P (SP) is an important neuropeptide involved in pain transmission and induction of inflammation. Its antagonists are being extensively investigated for their non-narcotic analgesic and anti-inflammatory activity. With a view towards better understanding the structural requirements of these analogs for efficient interaction with the SP receptor, the conformation of three SP antagonists [d-Arg1, d-Trp7,9, Leu11]-SP, [d-Arg1, d-Pro2, d-Trp7,9, Leu11]-SP and [d-Pro2, d-Trp7,9]-SP has been studied by CD, NMR and molecular dynamics (MD) simulations. All three peptides exhibit a high dependence of structure on the solvent. The molecules tend to adopt β-turns in solvents like DMSO and H2O and form helices in a hydrophobic environment. A direct relation between the helix forming potential of these antagonists with their receptor binding potency has been observed.
Keywords: SP peptide antagonist; 2d-NMR; Circular dichroism; Molecular dynamics;

Sauvagine analogs selective for corticotropin releasing factor 2 receptor: effect of substitutions at positions 35 and 39 on CRF2R selectivity by Adam W. Mazur; Feng Wang; Michelle Tscheiner; Elizabeth Donnelly; Robert J. Isfort (887-891).
Corticotropin releasing factor 2 receptor selective analogs of the amphibian peptide sauvagine, a member of the corticotropin releasing factor (CRF) peptide family, have therapeutic potential for the treatment of skeletal muscle atrophy. Previously, we demonstrated that [P11X12X13]Svg peptides have improved CRF2R selectivity, although not to the level of CRF2R selective hormones such as urocortin 2 and urocortin 3. Since we also demonstrated a potential for improvement in selectivity of sauvagine by modifications of residues 35 and 39, we investigated substitutions of these amino acids in selected [P11X12X13]Svg peptides. We have observed that substitution of Arg35 in sauvagine to Ala35 (the amino acid found in all CRF2R selective agonists), increased the selectivity of [P11, X12, X13]Svg analogs. In contrast, substitution of Asp39 in sauvagine to Ala39 (also the amino acid found in all CRF2R selective agonists) did not further increase the selectivity of [P11, X12, X13, A35]Svg analogs. Thus, the residues 35 along with 11, 12, and 13 in sauvagine represent important sites for improving CRF2R selectivity.
Keywords: Sauvagine; Corticotropin releasing factor receptor; Skeletal muscle atrophy;

Glutamate antagonists attenuate the action of NC-1900, a vasopressin fragment analog, on passive avoidance task performance in mice by Tomoaki Sato; Takayuki Ishida; Koh-ichi Tanaka; Nafees Chowdhurry; Masahiro Irifune; Kenji Hirate; Tamotsu Mimura; Takashige Nishikawa (893-897).
To examine the relationship between glutamate receptors and the action of NC-1900 on a step-through passive avoidance (PA) task in mice, MK-801, an NMDA receptor blocker, and (S)-4-carboxyphenylglycine (4CPG), a group I metabotropic receptor antagonist, were administered intraventricularly (i.c.v.) singly or as co-injections. The i.c.v. injection of MK-801 (0.8 μg) or 4CPG (2 μg) decreased the latency on the PA task. NC-1900 (1 ng/kg, subcutaneously (s.c.)) alone prolonged the latency on the retention trial in the PA task. MK-801 (0.2 and 0.8 μg) or 4CPG (0.5 and 2 μg) significantly inhibited the action of NC-1900, while the s.c. injection of NC-1900 did not affect latency in mice that received i.c.v. co-injection of MK-801 and 4CPG at any of the doses tested. These results suggest that glutamate receptors participate in the action of NC-1900 on learning and memory in PA task performance.
Keywords: NC-1900; Memory; MK-801; 4CPG; Glutamate receptor; Vasopressin analog;