Peptides (v.21, #8)

Combination studies between polycationic peptides and clinically used antibiotics against Gram-positive and Gram-negative bacteria by Andrea Giacometti; Oscar Cirioni; Maria Simona Del Prete; Alessandra Mataloni Paggi; Marcello Mario D’Errico; Giorgio Scalise (1155-1160).
The in vitro interaction between five polycationic peptides, buforin II, cecropin P1, indolicidin, magainin II, and ranalexin, and several clinically used antimicrobial agents was evaluated against several clinical isolates of Gram-positive and Gram-negative aerobic bacteria, using the microbroth dilution method. The combination studies showed synergy between ranalexin and polymyxin E, doxycycline and clarithromycin. In addition, magainin II was shown to be synergic with betalactam antibiotics.
Keywords: Bacteria; Synergy; Peptides; Susceptibility tests;

Linear and cyclic LFA-1 and ICAM-1 peptides inhibit T cell adhesion and function by Scott A Tibbetts; D.S.Seetharama Jois; Teruna J Siahaan; Stephen H Benedict; Marcia A Chan (1161-1167).
Short peptides derived from functional proteins have been used in several instances to inhibit activity of the parent proteins. In some cases, stability and efficacy were found to be increased by cyclization of these peptides. Inhibition of interaction of the two cell adhesion counter receptors leukocyte function-associated antigen (LFA)-1 and intercellular adhesion molecule (ICAM)-1 is being studied as a method for modulating autoimmune diseases such as rheumatoid arthritis and for facilitating organ transplantation. Here, several 10-amino acid peptides derived from the contact domains of LFA-1 and ICAM-1 were evaluated for their ability to interfere with intercellular adhesion by T cells and to inhibit a more biologic, mixed lymphocyte reaction. Both linear and cyclic forms of the peptides were effective at inhibiting intercellular adhesion. Cyclic forms were effective at inhibiting T cell activation and proliferation in the mixed lymphocyte reaction.
Keywords: LFA-1; ICAM-1; T cells; Intercellular adhesion; Mixed lymphocyte reaction;

The effects of the incretin hormone glucagon-like peptide 1 (7–36)amide (GLP-1) are mediated by the GLP-1 receptor (GLP-1R). This is expressed in a cell- and tissue-specific manner. Recently, we have cloned the 5′-flanking region of the human GLP-1R gene. The basal promoter activity is driven by the ubiquitous transcription factor Sp1. The tissue- and cell-specific expression of the gene requires several negatively acting cis-regulatory elements. We have now characterized one so far unknown distal cell-specific silencer element (DCS), repressing gene transcription of the human GLP-1R gene in fibroblasts and pancreatic A-cells, but not in pancreatic B- and D-cells. Our data suggests that the basal activity of the GLP-1R promoter is repressed in a tissue- and cell-specific manner by this novel silencer element.
Keywords: Gene expression; Cis-regulatory elements; Silencer; GLP-1 receptor promoter;

Splice variants of PAC1 receptor during early neural development of rats by Cheng-Ji Zhou; Sakae Kikuyama; Shigeo Nakajo; Takahiro Hirabayashi; Hidekatsu Mizushima; Seiji Shioda (1177-1183).
The specific pituitary adenylate cyclase-activating polypeptide (PACAP) receptor, PAC1-R, consists of at least seven isoforms, and they are differentially coupled to signal transduction pathways by alternative splicing. We have found that the major splice variants of the PAC1 receptor seen during development are the short splice isoform, PAC1-R-s (which does not contain either the “hip” or “hop” cassette), and another form, PAC1-R-hop (which contains the “hop” cassette). We also have applied an innovative molecular histochemical technique, in situ reverse transcription-polymerase chain reaction (RT-PCR), and determined that these two splice isoforms are colocalized in the neuroepithelia from the primitive streak stage.
Keywords: PACAP; G-protein coupled receptor; Splice variants; In situ RT-PCR; Neuroepithelia; Rat;

Tissue distribution of PACAP27 and -38 in oligochaeta: PACAP27 is the predominant form in the nervous system of Lumbricus polyphemus by Anikó Somogyvári-Vigh; Dóra Reglödi; Min Li; István Lengvári; Sándor Vigh; Akira Arimura (1185-1191).
The levels of pituitary adenylate cyclase-activating polypeptide (PACAP)27 and -38 were measured in the nervous, intestinal, excretory, and reproductive systems of Lumbricus polyphemus by radioimmunoassay. Although both PACAP27 and -38 were significantly detectable in all of the examined tissues, the distribution of the peptides was very heterogeneous. Their highest concentrations were found in the cerebral ganglia and the ventral cord, followed by the alimentary tract and the nephridial system, respectively. Moreover, the reproductive system also contained a substantial amount of PACAP. The dominant form of the peptide discovered in the majority of tissues was PACAP27. Interestingly, about 10 times more PACAP27 than PACAP38 was found, with the latter representing only a fraction of PACAP-like immunoreactivity in the tissues of Lumbricus polyphemus.
Keywords: Annelida; Evolution; Neuropeptides; PACAP; Radioimmunoassay;

Fifty-seven kinds of APGWamide-related peptides and a peptide library consisting of 38 peptide mixtures, each of which contained 19 kinds of APGWamide-related peptides, were synthesized with a multipeptide synthesizer, and their APGWamide-agonistic or -antagonistic effects were examined on the anterior byssus retractor muscle of the bivalve Mytilus edulis and the crop of the land snail Euhadra congenita. The peptide mixtures having agonistic or antagonistic effects were subjected to HPLC purification to isolate the active peptides using the muscles as bioassay systems. Many peptides having agonistic or antagonistic effects were obtained. Of the antagonists, APGWGNamide, isolated from the peptide mixture of APGWGXamide, was the most potent. At 10 4 M, APGWGNamide almost completely blocked the actions of 10 6 M APGWamide on the anterior byssus retractor muscle of M. edulis and the crop of E. congenita.
Keywords: Antagonist; APGWamide; APGWGNamide; molluscan; neuropeptide; multipeptide synthesizer;

Fulicin regulates the female reproductive organs of the snail, Achatina fulica by Yuko Fujisawa; Katsuyoshi Masuda; Hiroyuki Minakata (1203-1208).
Fulicin is a d-amino acid-containing neuropeptide that has been thought to control male copulatory behavior in the land snail, Achatina fulica. In the present study, we demonstrated that the vagina and the oviduct of Achatina were densely innervated by fulicin-like immunoreactive neuronal fibers. We confirmed that fulicin was actually present in the vagina by mass spectrometry. Furthermore, fulicin showed a profound excitatory effect on contractions of the vagina and the oviduct. These results suggest that fulicin controls female egg-laying behavior as an excitatory neuropeptide regulating the female reproductive organs of the snail.
Keywords: Neuropeptide; d-Amino acid-containing peptide; Fulicin; Immunohistochemistry; Mass spectrometry; Reproductive organ; Egg laying; Pulmonate; Mollusc; Achatina fulica;

Opposing interplay between Neuropeptide FF and nitric oxide in antinociception and hypothermia by Jean-Marie Zajac; Jean-Philippe Latapie; Bernard Francés (1209-1213).
This study examined the ability of the anti-opioid Neuropeptide FF (NPFF) to modify the endogenous activity of nitric oxide (NO). Antinociceptive and hypothermic effects of 1DMe (D.Tyr-Leu-(N.Me)Phe-Gln-Pro-Gln-Arg-Phe-NH2), an NPFF agonist, and of l-NAME (Nωnitro-l-arginine methyl ester), an inhibitor of nitric oxide synthase, were investigated in mice. Intraperitoneal (i.p.) injection of l-NAME induced, in the hot plate test, a dose-dependent antinociception not reversed by naloxone, an opioid antagonist, but inhibited by l-Arg, the NO synthesis precursor. Intracerebroventricular (i.c.v.) injections of 1DMe inhibit the antinociceptive activity of l-NAME in a dose-dependent manner. On the contrary, l-NAME markedly potentiated hypothermia induced by 1DMe injected in the third ventricle. These data show that Neuropeptide FF receptors exert a dual effect on endogenous NO functions and could modulate pain transmission independently of opioids.
Keywords: Neuropeptide FF (NPFF); Nitric oxide (NO); Analgesia; Hypothermia; Mouse;

Complete inhibition of purinoceptor agonist-induced nociception by spinorphin, but not by morphine by Hiroshi Ueda; Shinobu Matsunaga; Makoto Inoue; Yukio Yamamoto; Tadahiko Hazato (1215-1221).
We found that spinorphin, a novel neuropeptide showed analgesia in a different manner compared with morphine. By measuring flexor responses induced by the intraplanter injection of substances, the presence of three different types of sensory neurons were demonstrated. Although spinorphin completely blocked 2-metylthioadenosine (2-MeS ATP, a P2X3 agonist)-induced responses, morphine did not. On the other hand, morphine-induced blockade of bradykinin (BK, a B2-receptor agonist)-responses was attenuated by pertussis toxin (PTX) treatment, whereas that of spinorphin was not. Thus it is suggested that spinorphin has a spectrum of analgesia which covers the blockade of nociception insensitive to morphine.
Keywords: Spinorphin; P2X3; Bradykinin; 2-MeS ATP; PGI2 agonist; Gi;

Opioid peptide modulation of circulatory response to hyperventilation in humans by Fiorella Fontana; Pasquale Bernardi; Emilio Merlo Pich; Lucia Tartuferi; Stefano Boschi; Santi Spampinato (1223-1230).
After hyperventilation, systolic blood pressure (SBP) significantly decreased in 10 subjects (group 1), did not change in eight (group 2) and increased in 15 (group 3). Diastolic blood pressure and heart rate increased in all groups. The decrease in SBP was associated with a decrease in plasma catecholamines and increase in β-endorphin, whereas the increase in SBP was accompanied by an increase in catecholamine and Met-enkephalin levels. Naloxone abolished the hyperventilation-induced SBP and catecholamine decrease only in group 1. These findings show an activation of the endogenous opioid system after hyperventilation and the role of β-endorphin in reducing SBP in response to the test.
Keywords: Hyperventilation; β-endorphin; Dynorphin B; Met-enkephalin; Naloxone; Norepinephrine; Epinephrine; Atrial natriuretic factor; Endothelin-1;

Unlike thrombin, protein C and activated protein C do not affect vascular tone by Anindya Bhattacharya; Brian W Grinnell; Marlene L Cohen (1231-1236).
Because plasma levels of protein C (PC) or activated protein C (APC) are altered in certain diseases associated with vascular dysfunction, and APC has therapeutic potential in preventing microvascular coagulation in severe sepsis, potential vascular effects of PC and APC were compared to those of the vasoactive peptide, thrombin. Thrombin was a more potent relaxant agonist than contractile agonist in aorta. Unlike thrombin, cumulatively administered APC (10−9-10−7 M) did not exert vascular effects in rat or rabbit aorta. Noncumulative challenge of PC (10−7 M) and APC (8 × 10−8 M) also did not contract rat or rabbit aortae, either with or without endothelium. Likewise, the same concentrations of PC and APC also did not relax norepinephrine-induced (10−7 M) vascular tone in either rat or rabbit aortae. Thus, in contrast to thrombin, PC and APC failed to modulate vascular tone, suggesting that the therapeutic use of APC is unlikely to be accompanied by any direct effects on vascular motility.
Keywords: Thrombin; Protein C (PC); Activated protein C (APC); Vascular effect;

The ability of angiotensin II (ang II) to produce apoptosis is controversial. Cardiomyocytes, isolated from 7-day embryonic chick hearts and maintained in culture for 72 h, were treated with ang II. There was no evidence of ang II-induced apoptosis consistently demonstrated by six different techniques: electrophoretic separation of fragmented DNA, staining with TUNEL, enzyme-linked immunosorbent assay specific for fragmented DNA, dual staining of cells with fluorescein diacetate and propidium iodide with analysis by flow cytometry, staining of nuclei with propidium iodide and cell microscopy. In contrast, apoptosis was readily induced by camptothecin or staurosporine or serum deprivation. The absence of ang II-induced cell death was also demonstrated in neonatal mouse cardiomyocytes in culture. We further sought to answer the question whether ang II Type 1 receptor blockade by antagonizing the potential beneficial effects mediated through this receptor and producing more ang II binding to the ang II Type 2 receptors, would lead to cardiac apoptosis. There was no evidence of ang II-induced apoptosis in the presence of the ang II Type 1 receptor antagonist losartan in embryonic chick cardiomyocytes. Rather ang II prevented serum deprivation-induced apoptosis. In summary, in these cardiomyocytes ang II does not induce but rather prevents apoptosis.
Keywords: Ang II; Losartan; Apoptosis; Cardiomyocytes; Serum deprivation;

Peptidase inhibitors and identification of the peptide fragments were used for the characterization of the bradykinin metabolism by alveolar and peritoneal macrophages. Both cell types show differences in the rate of inactivation and in the quantity of the metabolites generated. BK(1–5), BK(1–8), and BK(1–7) are the predominant direct metabolites. Metalloendopeptidase 24.15, carboxypeptidase M, and an unidentified peptidase are responsible for their formation. Angiotensin-converting enzyme and neutral endopeptidase 24.11 do not play a crucial role in the degradation of bradykinin by macrophages. In the bronchoalveolar space, other cells than the macrophages are more important to the breakdown of this peptide.
Keywords: Bradykinin; Kinin metabolism; Macrophages; Bronchoalveolar lavage fluid; Metalloendopeptidase 24.15; Carboxypeptidase M; Neutral endopeptidase 24.11; Angiotensin-converting enzyme;

Potentiation of the effects of bradykinin on its receptor in the isolated guinea pig ileum by Richard D Minshall; Sumol J Nedumgottil; Rajko Igić; Ervin G Erdös; Sara F Rabito (1257-1264).
Angiotensin I-converting enzyme (ACE/kininase II) inhibitors potentiated guinea pig ileum’s isotonic contractions to bradykinin (BK) and its analogues, shifting the BK dose-response curve to the left. ACE inhibitors added at the peak of the contraction immediately enhanced it further (343 ± 40%), although the ileum inactivated BK slowly (t1/2 = 12–16 min). Chymotrypsin and cathepsin G also augmented the activity of BK up to three- or four-fold, but in a manner slower than that of ACE inhibitors. The BK B2 receptor blocker HOE 140 inhibited all effects. Histamine and angiotensin II were not potentiated. ACE inhibitors potentiate BK independent of blocking its inactivation by inducing crosstalk between ACE and the BK B2 receptor; proteases activate the receptor by different mechanism. (110 words)
Keywords: Kininase II; ACE inhibitors; Chymotrypsin; Cathepsin G; Bradykinin B2 receptor; Sensitization; Potentiation;

Bombesin improves burn-induced intestinal injury in the rat by İnci Alican; E.Erol Ünlüer; Cumhur Yeğen; Berrak Ç Yeğen (1265-1269).
This study was designed to determine the effect of exogenous bombesin (10 μg/kg/day, subcutaneously, three times a day) on intestinal hypomotility and neutrophil infiltration in the early and late phases of burn injury (partial-thickness, second-degree burn of the skin). In acute (2 h after burn injury) or chronic (3 days after) burn groups, intestinal transit was delayed, which was reversed by bombesin treatment. In the acute burn group, but not in the chronic group, increased MPO activity was also reduced by bombesin treatment. The results demonstrate that bombesin ameliorates the intestinal inflammation due to burn injury, involving a neutrophil-dependent mechanism.
Keywords: Bombesin; Burn injury; Hypomotility; Neutrophils;

The effect of α-melanocyte stimulating hormone on colonic inflammation in the rat by Berna K Oktar; Feri̇ha Ercan; Berrak Ç Yeğen; İnci̇ Ali̇can (1271-1277).
The effect of α-melanocyte stimulating hormone (α-MSH) on colonic inflammation in the rat. In this study, we investigated the effects of α-MSH administration on trinitrobenzene sulfonic acid-induced colitis and the role of nitric oxide and prostaglandins in this response. α-MSH treatment (25 μg/rat, intraperitoneally; twice daily for 3 days) reduced the colonic macroscopic lesions compared to untreated ones in both acute and chronic colitis groups. This effect was reversed by pretreatment with the nitric oxide donor, sodium NP (4 mg/kg, intravenously) or cyclooxygenase-1 selective antagonist indomethacin (5 mg/kg, subcutaneously) in the acute group and with the cyclooxygenase-2 selective antagonist nimesulide (3 mg/kg, subcutaneously) in the chronic group. α-MSH had no effect on colonic wet weight and myeloperoxidase acitivity compared to the untreated colitis group. However, protein oxidation was markedly elevated in the α-MSH-treated group compared to untreated ones. Nitroprusside and indomethacin reversed the effect of α-MSH on macroscopic lesions in the acute groups, whereas nimesulide showed a similar effect in the chronic group. In conclusion, the results of our study show a protective role of α-MSH on colonic lesions which partially involves nitric oxide and prostaglandins.
Keywords: Colitis; α-Melanocyte stimulating hormone; Nitric oxide; Prostaglandins; Neutrophils;

The rewarding properties of neuropeptide Y in perifornical hypothalamus vs. nucleus accumbens by Christina M Brown; Donald V Coscina; Paul J Fletcher (1279-1287).
There is a high coexistence of substance abuse in humans with eating disorders. One theory offered to account for this fact is that a common biochemical substrate may exist that mediates both processes. Brain neuropeptide Y (NPY) is one neurochemical system that might contribute to these separate, yet related, problems. To clarify the role of NPY in mediating reward processes and the possible interaction between reward and feeding, the present study examined the effects of injecting NPY bilaterally into the perifornical hypothalamus (PFH) vs. the nucleus accumbens (NAC) on intake of preferred vs. non-preferred food types, as well as on conditioned place preference (CPP) learning. NPY (24, 78, 156 and 235 pmol/side) stimulated intake of both regular powdered chow and sucrose when injected into the PFH, but not the NAC. A CPP that was negatively correlated with food intake occurred with the low (24 pmol/side) dose of NPY in the PFH, while a CPP that was not correlated with food intake was produced with the same dose in the NAC. The extent of the CPPs produced by NPY injection in both brain sites mirrored that produced by peripheral injection of amphetamine (2.5 mg/kg). These results indicate that NPY elicits reward-related behavior, but not feeding, from the NAC, and both behaviors from the PFH. However, the feeding effect derived from the PFH appears to overshadow a rewarding effect derived from this site. Considered together, these findings suggest that altered NPY functioning in both brain regions may contribute to some of the pathophysiological processes observed in eating disordered patients who have additional proclivities for substance abuse.
Keywords: NPY; Rat; Amphetamine; Intracerebral; Conditioned place preference; Feeding;

Chromogranins belong to an evolutionarily conserved family of proteins that serve as neuropeptide pro-proteins, besides having other functions. The secretogranin-II-derived peptide secretoneurin is a 33-amino-acid polypeptide generated by proteolytic cleavage at paired dibasic sequences that exerts its effect by binding to specific receptors. Secretoneurin receptors have been kinetically and functionally characterized indicating that they are G-protein linked. Localization of secretoneurin and functional studies have helped to elucidate roles for secretoneurin, ranging from effects in the central nervous system to the modulation of the inflammatory response in the periphery. It has been shown that secretoneurin possesses biologic activities such as stimulation of dopamine release from striatal neurons and activation of monocyte migration, suggesting that the peptide may modulate both neurotransmission and inflammatory response. With an array of actions as diverse as that seen with other sensory neuropeptides, there is scope for numerous studies and therapeutic possibilities.
Keywords: Neuropeptides; Chromogranins; Secretogranin-II; Receptor; Brain; Immune system; Leukocytes; Human; Neuroimmunomodulation;