Peptides (v.22, #9)
Helospectin, induces a potent relaxation of human airways in vitro by Monika Cardell; Lars-Olaf Cardell (1359-1362).
Helospectin is a neuropeptide of the vasoactive intestinal polypeptide/secretin/glucagon family. Several members of this family display biological activities relevant to obstructive airway disease and although the literature in this area is rapidly expanding very little is known about the effects of helospectin. The smooth muscle relaxation induced by helospectin on human bronchi and pulmonary arteries were therefore assessed in vitro, using tissue baths. Helospectin induced a potent relaxation of human bronchi and since helospectin-like immunoreactive nerve fibers along with possible target receptors previously have been reported in the human lung, helospectin might play a role in endogenous regulation of airway tone.
Keywords: Helospectin; In vitro pharmacology; Bronchi; Pulmonary artery; Lung;
Proline residue 280 in the second extracellular loop (EC2) of the VPAC2 receptor is essential for the receptor structure 2 2 Abbreviations: CHO, Chinese hamster ovary cells; EC, extracellular loops; EC50, concentration of agonist required for half maximal response; GRF, growth hormone releasing factor; IC, intracellular domain; IC50, concentration of ligand required for 50% inhibition of tracer binding; PCR, polymerase chain reaction; TM, transmembrane domain; VIP, vasoactive intestinal polypeptide; VIP1 agonist, [K15, R16, L27] VIP (1–7)/GRF (8–27); VIP1 antagonist, Ac His1 [D-Phe2, K15, R16, L27] VIP (3–7)/GRF (8–27); Ro 25–1553, Ac His1[E8, K12, Nle17, A19, D25,L26, K 27, K28, G29, G30, T31] cyclo 20–25 VIP (2–24); C6-VIP, [hexanoyl-His1]-VIP. by P. Vertongen; R.M. Solano; M.G. Juarranz; J. Perret; M. Waelbroeck; P. Robberecht (1363-1370).
Inspection of the amino acid sequence of the human VPAC1 and the VPAC2 receptors after alignment of the conserved residues indicates that the second extracellular loop (EC2) is one amino acid shorter in the VPAC1 receptor due to the lack of a proline residue in position 294. We hypothesized that this could be of importance for receptor structure and/or for ligand recognition. Insertion by directed mutagenesis of a proline in that position (〈Pro〉294 VPAC1) had little consequence on the binding of several agonists but reduced the affinity for the VPAC1 antagonist. Coupling of the 〈Pro〉294 VPAC1 receptor to adenylate cyclase was improved, as demonstrated by an increased affinity for VIP and other agonists, and by a shift of the VPAC1 antagonist to partial agonist behavior. Deletion of the proline 280 (ΔPro280 VPAC2) in the VPAC2 receptor markedly reduced the apparent affinity for all the agonists tested. Replacement of the proline by a glycine residue had a smaller effect on the ligands affinities. The proline residue in the VPAC2 receptor EC2 is thus essential for the receptor structure, and the EC2 domain is involved in ligand recognition and receptor functionality.
Keywords: VPAC1 receptor; VPAC2 receptor; Adenylate cyclase activity;
Distribution and daily variations of PACAP in the chicken brain by R. Józsa; A. Somogyvári-Vigh; D. Reglödi; T. Hollósy; A. Arimura (1371-1377).
Levels of PACAP38 were measured in different areas of the chicken brain under various lighting conditions by radioimmunoassay (RIA). Selected groups of animals were maintained under light for 14 h alternating with 10 h of darkness (LD), reversed lighting conditions (DL) and constant light (LL) or constant dark (DD). Daily variations of PACAP levels were observed in the brainstem, diencephalon, telencephalon and retina. In the brainstem and diencephalon, levels of PACAP increased during subjective nighttime, except in the DL group where levels were elevated between 15–21 h. In the telencephalon, the lowest level of PACAP was measured between 12–21 h except in the DL group where two peaks occurred at 18 and 03 h. In the retina, all 4 groups showed a similar level and pattern, with lowest levels during midday hours. No daily variation was observed in the pineal gland. According to the present observations, it is suggested that PACAP levels differ in several areas of the chicken brain under various lighting conditions and photic stimuli do not appear to be the main regulators of the circadian variations of PACAP.
Keywords: PACAP; chicken; daily variation; radioimmunoassay;
Pyrokinin/PBAN radio-receptor assay: development and application for the characterization of a putative receptor from the pheromone gland of Heliothis peltigera☆ 1 1 ☆ Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No 505/01, 2001 series. by Miriam Altstein; Orna Ben-Aziz; Shai Daniel; Irina Zeltser; Chaim Gilon (1379-1389).
A radio-receptor assay (RRA) for the insect pyrokinin/PBAN family has been developed. The development involved examination of the ligand (3H-tyrosyl-PBAN28–33NH2)-receptor interaction under various incubation conditions and variations on sex pheromone gland membrane preparation. Application of the RRA for a partial characterization of the putative pyrokinin/PBAN receptor in the pheromone gland of H. peltigera revealed age-dependence of its expression. Pharmacological characterization revealed a high correlation between the binding-affinity to the receptor of various PBAN-derived peptides and their in vivo pheromonotropic bioactivity, and shed light on the interaction of backbone cyclic and linear ([Arg27,D-Phe30]PBAN28–33NH2) PBAN antagonists with the receptor.
Keywords: PBAN receptor; PBAN; pheromone gland; Heliothis peltigera; Insect neuropeptide; moths; radio receptor assay;
Characterization of a novel Sepia officinalis neuropeptide using MALDI-TOF MS and post-source decay analysis by L.F. Marvin; C. Zatylny; J. Leprince; H. Vaudry; J. Henry (1391-1396).
A novel neuropeptide acting as a myosuppressor on esophagus, funnel and mantle muscular fibers has been isolated from the stellar ganglia of the mollusk cephalopod Sepia officinalis by means of HPLC analysis. Fractions were monitored using a myotropic bioassay. After three separation steps, MALDI-TOF spectrum revealed one main peak at m/z 756.6. The partial N-terminal and C-terminal digestions by exopeptidases followed by MALDI-TOF analysis allowed the determination of the nature of the two C-terminal and N-terminal amino acids. Post Source Decay fragmentation of the molecular ion accurately determined the following primary sequence: Val-Tyr-Ser-Ala-Pro-Tyr-Gly-OH. The mapping of this heptapeptide performed in ESI-MS revealed that its distribution is restricted to the stellar ganglia, the giant fibers III, and the nervous bundle containing the giant fibers II and the palleal nerve. The neuropeptide was not detected in the hemolymph suggesting a release by nerve endings next to the targets.
Keywords: MALDI-PSD-TOF MS; ESI-MS; HPLC; neuropeptide; Invertebrate; Mollusk; Sepia officinalis; stellar ganglia; esophagus;
Effects of two novel non-peptide antagonists at the rabbit bradykinin B2 receptor by François Marceau; Steeve Houle; Johanne Bouthillier; Najeeb B. Said; Peter J. Garratt; Edward K. Dziadulewicz (1397-1402).
Large species differences have been previously observed in the pharmacology of bradykinin (BK) B2 receptor antagonists. We investigated the effect of two novel non-peptide antagonists, compound 9 (a benzodiazepine peptidomimetic related to icatibant) and the thiosemicarbazide bradyzide on the rabbit B2 receptor (contractility of the jugular vein, competition of [3H]BK binding to a B2 receptor-green fluorescent protein (B2R-GFP) conjugate, subcellular distribution of B2R-GFP). While compound 9 is about 9000-fold less potent than icatibant, it shares with the latter peptide drug a selective, insurmountable and largely irreversible antagonist behavior against BK and the capacity to translocate B2R-GFP from the membrane into the cells. Bradyzide, reportedly very potent at rodent B2 receptors, was a competitive and reversible antagonist of moderate potency at the rabbit B2 receptor (contractility pA2 6.84, binding competition IC50 5 nM). The C-terminal region of icatibant, reproduced by compound 9, is likely to be important in the non-equilibrium behavior of icatibant. Bradyzide, a non-peptide antagonist developed on different structural grounds, is competitive at the rabbit B2 receptor.
Keywords: Non-competitive pharmacological antagonism; Icatibant; Bradykinin; Rabbit jugular vein; B2 receptor; Bradyzide;
Angiotensin IV enhances LTP in rat dentate gyrus in vivo by Matthew J. Wayner; Deborah L. Armstrong; Clyde F. Phelix; John W. Wright; Joseph W. Harding (1403-1414).
Angiotensins have been shown to play a significant role in a variety of physiological functions including learning and memory processes. Relatively recent evidence supports the increasing importance of angiotensin IV (Ang IV), in many of these functions previously associated only with Ang II, including learning and memory. An interesting hypothesis generated by these results has been that Ang II is a precursor for the production of a more active peptide fragment, Ang IV. Since Ang II impairs learning and memory, when administered directly or released into the hippocampal dentate gyrus, and inhibits long term potentiation (LTP) in medial perforant path-dentate granule cell synapses, as well; it remained to be seen what effects Ang IV had on LTP in these same synapses. Results of this study show clearly that Ang IV significantly enhances LTP, and the enhancement is both dose and time dependent. The following solutions of Ang IV were administered over a five min period, at the end of baseline and before the first tetanus was applied: 2.39, 4.78, and 9.56 nM. An inverted U-type dose related effect was observed. A complex time related effect was observed with a maximum at 5 min, a return to normal LTP at 30 min and a minimum below normal at 90 min, and a return to normal LTP at 120 min. The effects of the 4.78 nM solution were determined at the following intervals between administration and the first tetanus: 5, 15, 30, 60, 90, and 120 min. The enhancement of LTP can be prevented by pretreatment with Divalinal, an Ang IV antagonist, without any effect on normal LTP. Two solutions of Divalinal were used; 5 nM and 5 μM, and the 5 μM was more effective and completely blocked the enhancement of normal LTP. Results were also obtained with 4.78 nM Nle1-Ang IV (Norleucine), an Ang IV agonist. Norleucine was less effective than Ang IV in the enhancement of normal LTP and displayed a similar time course of activity. Both Ang IV and Norleucine produced a significant suppression of normal LTP at 90 min; that remains to be explained. However, the inhibition by Ang IV was dose dependent and was blocked by Divalinal. The fact that the Ang IV enhancement of normal LTP was blocked by losartan, an Ang II AT1 receptor antagonist, is puzzling since Divalinal had no effect on the inhibition of LTP by Ang II.
Keywords: Angiotensin IV; Long term potentiation; Dentate gyrus; LTP; Hippocampus;
A central link between angiotensinergic and cholinergic systems; role of vasopressin by Naciye Isbil- Buyukcoskun; Guldal Gulec; Kasim Ozluk (1415-1420).
Participation of central cholinergic system in the effects of intracerebroventricular (i.c.v.) injection of angiotensin II (Ang II) on blood pressure and heart rate was studied in conscious, freely moving rats. Ang II dose-dependently increased blood pressure and decreased heart rate. Both atropine and mecamylamine (i.c.v.) pretreatments prevented the cardiovascular effects of Ang II. Pretreatment with a vasopressin V1 antagonist also prevented the cardiovascular responses to Ang II. Our data suggest that the central pressor effect of Ang II is mediated in part by central acetylcholine via both muscarinic and nicotinic receptors, and vasopressin participates in this effect through V1 receptors.
Keywords: Intracerebroventricular; Ang II; Cholinergic system; V1 antagonist; Blood pressure; Heart rate;
Histamine release induced by dendroaspis natriuretic peptide from rat mast cells by Ok Hee Chai; Eun Kyoung Kim; Young-Hoon Lee; Jae-Gon Kim; Byeong-Ju Baik; Moo Sam Lee; Eui-Hyeog Han; Hyoung Tae Kim; Chang Ho Song (1421-1426).
Dendroaspis natriuretic peptide (DNP), recently isolated from the venom of the green Mamba snake Dendroaspis angusticeps, is a 38 amino acid peptide containing a 17 amino acid disulfide ring structure similar to that of the natriuretic peptide family. The natriuretic peptide family is known to induce histamine release from human and rat mast cells, but there are no published data concerning the effects of DNP on histamine release from mast cells. The purpose of this study is to investigate whether DNP induces the histamine release from rat peritoneal mast cells (RMPCs) and to determine the mechanism of DNP-induced histamine release from RPMCs. After treatment of RPMC with DNP, mast cell degranulation was observed, and calcium uptake and histamine release were measured. DNP released the histamine, induced the mast cell degranulation, and increased the calcium uptake of RPMCs, in a dose-dependent manner. The results indicate that DNP can increase Ca-uptake and induce histamine release.
Keywords: Dendroaspis natriuretic peptide (DNP); Mast cell; Degranulation; Histamine; Calcium;
Analysis of responses to hAmylin, hCGRP, and hADM in isolated resistance arteries from the mesenteric vascular bed of the rat by Hunter C. Champion; Robert L. Pierce; Trinity J. Bivalacqua; William A. Murphy; David H. Coy; Philip J. Kadowitz (1427-1434).
Responses to human calcitonin gene-related peptide (hCGRP) and human adrenomedullin (hADM) hAmylin were investigated in isolated mesenteric resistance arteries from the rat. The results of the present investigation show that hCGRP, hAmylin, and hADM induce dose-related vasodilator responses in isolated resistance arteries from the rat mesenteric vascular bed. Vasodilator responses to hCGRP and hAmylin were not altered after denuding the vascular endothelium, after administration of the nitric oxide synthase inhibitor L-NA, or after administration of the soluble guanylate cyclase inhibitor ODQ, suggesting that vasodilator responses to hCGRP and hAmylin are not mediated by the release of nitric oxide from the vascular endothelium and the subsequent increase in cGMP. Vasodilator responses to hCGRP, hAmylin, and hADM were not altered by the vascular selective K+ ATP channel antagonist U-37883A. The role of the CGRP1 receptor was investigated and responses to hCGRP and hAmylin, but not hADM, were significantly reduced following administration of hCGRP-(8–37). Moreover, vasodilator responses to hCGRP and hAmylin, but not hADM, were significantly reduced by hAmylin-(8–37), suggesting that an hAmylin-(8–37)-sensitive receptor mediates responses to hCGRP and hAmylin in the rat mesenteric artery. These data suggest that hCGRP and hAmylin have direct vasodilator effects in the isolated mesenteric resistance artery that are mediated by hAmylin-(8–37)- and hCGRP-(8–37)-sensitive receptors.
Keywords: Amylin; Calcitonin gene-related peptide; CGRP1 receptor; Vasodilator responses; Mesenteric vascular bed; Adrenomedullin;
Cloning of a calcitonin gene-related peptide from genomic DNA and its mRNA expression in flounder, Paralichthys olivaceus 1 1 The sequence data have been submitted to DDBJ/GenBank/EMBL under Accession No. AB052782. by Nobuo Suzuki; Tohru Suzuki; Tadahide Kurokawa (1435-1438).
A part of genomic DNA including the calcitonin gene-related peptide (CGRP) gene was cloned from flounder by the genome-walking method. The intron/exon boundary was predicted to occur exactly at the same position as in salmon. The 37-amino acid molecule coded by the region from the intron/exon boundary to the stop codon was preceded by a typical Lys-Arg cleavage signal and included a cleavage/amidation site common to the CGRP of other vertebrates. The predicted amino acid sequence of flounder CGRP had 78%, 78%, 78%, 81%, and 73–78% identity to that of salmon, cod, frog, chicken, and mammalian CGRPs, respectively. Among vertebrates, CGRP is more conserved than calcitonin (CT) because the identity of flounder CT to mammalian CTs is 31–50%. Expression analysis indicated that this hormone is synthesized in the brain, heart, intestine, testis, and ovary. Since we have previously shown that the CGRP receptor is expressed in these tissues, it is suggested that CGRP secreted from each tissue functions in a paracrine or autocrine manner.
Keywords: Calcitonin; Calcitonin gene-related peptide; Genome walking method; Flounder; Polymerase chain reaction (PCR); Tissue expression;
The capsaicin VR1 receptor mediates substance P release in toxin A-induced enteritis in rats by Douglas C. McVey; Steven R. Vigna (1439-1446).
The mechanism by which Clostridium difficile toxin A causes substance P (SP) release and subsequent inflammation in the rat ileum is unknown. Pretreatment with the vanilloid receptor subtype 1 (VR1) antagonist, capsazepine, before toxin A administration significantly inhibited toxin A-induced SP release and intestinal inflammation. Intraluminal administration of the VR1 agonist capsaicin caused intestinal inflammation similar to the effects of toxin A. Pretreatment with capsazepine before capsaicin administration also significantly inhibited capsaicin-induced intestinal inflammation. These results suggest that intraluminal toxin A causes SP release from primary sensory neurons via stimulation of VR1 receptors resulting in intestinal inflammation.
Keywords: Substance P; Capsazepine; Vanilloid receptor subtype 1; Neurogenic inflammation; Intestinal inflammation; Capsaicin receptor;
Place aversion induced by microinjections of C-fragment of substance P into the dorsal periaqueductal gray of rats is mediated by tachykinin NK1 receptors by João E. De Araújo; Joseph P. Huston; Marcus L. Brandão (1447-1452).
Neural circuits in the dorsal periaqueductal gray matter (dPAG) play an important role in the integration of defensive behavior. The neurokinin substance P causes conditioned place aversion when administered into this region. The present study examined whether these effects may be mimicked by its carboxy-terminal amino acid sequence and whether they are influenced by prior treatment with the tachykinin NK1 receptor antagonist WIN51,708. The behavioral testing apparatus is a circular open field consisting of 4 uniform quadrants that are equally preferred by the rats prior to drug treatments. For conditioning, rats received drug injections on three consecutive days and were placed into their assigned quadrant. The carboxy-terminal analog (17.5 pmol/0.2 μl) applied into the dPAG produced place aversion effects with reduced time spent in the drug-paired quadrant on the testing day. The effects of the carboxy-terminal analog was antagonized by pretreatment with WIN51,708 (20 mg/kg, i.p.). Microinjection of WIN51,708 (20 mg/kg, i.p.), by its own, did not produce significant effects. These findings suggest that previous reports showing conditioned place aversion effects of SP injected into the dPAG are encoded by its carboxy-terminal sequence and due to its action on tachykinin NK1 receptors.
Keywords: dPAG; Substance P; C-fragment; NK1 receptors; Place aversion; Corral test;
Substance P and its transglutaminase-synthesized spermine derivative elicit yawning behavior via nitric oxide in rats 1 1 Abbreviation: SP, Substance P; Spm, spermine; Spm-SP γ-(glutamyl5)spermine derivative of sustance P; D- and L-NAME, N4-nitroarginine methyl ester; NO, nitric oxide. by Franca Mancuso; Raffaele Porta; Antonio Calignano; Prospero Di Pierro; Maria G. Sommella; Carla Esposito (1453-1457).
Previously, we showed that intranigrostriatal injection of substance P (SP) cause behavioral changes in rats. Those effects, such as locomotion and food intake, resulted related to catecholamines release modulated by nitric oxide . Here we report that intranigrostriatal injection of SP elicited yawning in rats. Moreover, since in previous studies we demonstrated that transglutaminase-synthesized γ-(glutamyl5)spermine derivative of SP (Spm-SP) could be a useful tool in differentiating NK1 receptors , we reports the effects of injecting the selective septide-sensitive NK1 receptor agonist Spm-SP into the nigrostriatal region of the rat brain on yawning. The administration of L-Nω-nitroarginine methyl ester, a NO-synthase inhibitor, stereospecifically reduced in a dose related manner both SP and Spm-SP-induced yawning. In contrast, L-arginine pretreatment prevented the effect of NO-synthase inhibitor. Moreover, the NK1 antagonist RP,67580 blocked yawning behavior induced by both SP and Spm-SP, whereas the pretreatment with systemic reserpine determined its increase. The administration of NO-synthase inhibitor resulted ineffective in reducing SP and Spm-SP-induced yawns in reserpinized rats. Finally, yawns elicited by SP or Spm-SP were blocked when rats were treated with scopolamine but not with methylscopolamine.These results indicate that yawning induced in rats by SP injection is dependent upon endogenous dopamine levels in brain nigrostriatal area. Moreover, we demonstrate, by using Spm-SP, that septide-sensitive NK1 receptor are specifically involved in yawning behavior.
Keywords: Substance P; Nitric oxide; Yawning; Transglutaminase; Spermine;
Behavioral and neuroendocrine actions of endomorphin-2 by E. Bujdosó; M. Jászberényi; C. Tömböly; G. Tóth; G. Telegdy (1459-1463).
The effects of intracerebroventricularly administered endomorphin-2 (EM2) on open-field activity and the hypothalamo-pituitary-adrenal (HPA) system were investigated. EM2 (0.25–1 μg) significantly increased both the locomotor and the rearing activity, resulting in a bell-shaped dose-response curve. EM2 also enhanced corticosterone release, with an even more profound downturn phase at higher concentrations. The corticotropin-releasing hormone (CRH) antagonist α-helical CRH9–41 completely abolished the EM2-evoked endocrine and behavioral responses. These findings reinforce the hypothesis that the endomorphins may play a significant role in the regulation of locomotion, rearing activity and the HPA system through the release of CRH.
Keywords: Endomorphin-2; Open-field behavior; HPA axis;
β-Endorphin- and GABA-mediated depressor effect of specific electroacupuncture surpasses pressor response of emotional circuit by Yun-Hui Ku; Yan-Zhong Chang (1465-1470).
It has been proved that input of specific electroacupuncture (EA) can activate β-endorphin(β-EP)ergic and noradrenergic neurons projecting to the rostral ventrolateral medulla (RVL), the latter acting upon the RVL-GABAergic interneurons, thereby produce depressor effect. The present study further shows that: (1) The EA depressor effect is strong enough to surpass the pressor response of the AC (nucleus amygdaloideus centralis)-emotional circuit, (2) both β-endorphin (β-EP) and GABA in the RVL mediate the EA antagonistic effect, (3) the EA effect does not take place in the AC and paraventricular nucleus (two key nuclei besides the RVL, which also have β-EPergic input) in the emotional circuit.
Keywords: Blood pressure; Emotion; Stress; Central nervous system; β-Endorphin; GABA; Acupuncture;
Structure-activity relationships of neuropeptide FF: role of C-terminal regions by Honoré Mazarguil; Christine Gouardères; Jean-André M. Tafani; Delphine Marcus; Masato Kotani; Catherine Mollereau; Michel Roumy; Jean-Marie Zajac (1471-1478).
A structure-activity study was carried out to determine the importance of the C-terminal amino acids of the octapeptide Neuropeptide FF (NPFF) in binding and agonistic activity. Affinities of NPFF analogues were tested toward NPFF receptors of the rat spinal cord and the human NPFF2 receptors transfected in CHO cells. The activities of these analogues were evaluated by their ability to both inhibit adenylate cyclase in NPFF2 receptor transfected CHO cells and to reverse the effect of nociceptin on acutely dissociated rat dorsal raphe neurons. The substitutions of Phenylalanine8 by a tyrosine, phenylglycine or homophenylalanine were deleterious for high affinity. Similarly, the replacement of Arginine7 by a lysine or D.Arginine induces a loss in affinity. The pharmacological characterization showed that the presence of the amidated Phe8 and Arg7 residues are also extremely critical for activation of anti-opioid effects on dorsal raphe neurons. The sequence of the C-terminal dipeptide seems also to be responsible for the high affinity and the activity on human NPFF2 receptors. The results support the view that a code messaging the molecular interaction toward NPFF-receptors is expressed in the C-terminal region of these peptides but the N-terminal segment is important to gain very high affinity.
Keywords: NPFF receptors; synthetic peptide; binding; affinity; agonist activity;
Oxytocin decreases carrageenan induced inflammation in rats by Maria Petersson; Ursula Wiberg; Thomas Lundeberg; Kerstin Uvnäs-Moberg (1479-1484).
The effects of oxytocin on carrageenan-induced inflammation in rat hindpaw was examined. Oxytocin at 100 (P < 0.05) and 1000 μg/kg s.c. (P < 0.05), but not at 1 and 10 μg/kg s.c., reduced the edema of the paw when measured up to 10 h after the injection. An additional experiment showed that the effect was comparable to the effect of the glucocorticoid dexamethasone. No effect was found by oxytocin i.c.v.In addition, rats with carrageenan-induced inflammation given oxytocin (1000 μg/kg s.c.) responded differently to nociceptive mechanical stimulation (P < 0.05) and had a reduced amount of myeloperoxidase (marker for neutrophil recruitment) in the paw (P < 0.01).
Keywords: Oxytocin; Oxytocin antagonist; Myeloperoxidase; Dexamethasone; Inflammation; Carrageenan; Rat; Nociceptive thresholds;
Adrenomedullin expression in pathogen-challenged oral epithelial cells by Supriya Kapas; Amerjote Bansal; Vijay Bhargava; Raj Maher; Davinder Malli; Eleni Hagi-Pavli; Robert P. Allaker (1485-1489).
Adrenomedullin, a multifunctional peptide, is expressed by many surface epithelial cells and, previously, we have demonstrated that adrenomedullin has antimicrobial activity. The oral cavity contains an epithelium that is permanently colonized by microflora, yet infections in a host are rare. We exposed oral keratinocytes to whole, live cells from four microorganisms commonly isolated from the oral cavity, Porphyromonas gingivalis, Streptococcus mutans, Candida albicans and Eikenella corrodens. There was upregulation of protein and gene expression in these cells in response to bacterial suspensions, but not with the yeast, Candida albicans. We propose there is a potential role for microbial products in enhancing mucosal defense mechanisms and that adrenomedullin participates in the prevention of local infection, thus contributing to host defense mechanisms.
Keywords: Adrenomedullin; Oral epithelium; Antimicrobial; Host defense mechanism; Beta defensin;
Evidence that the chromogranin B fragment 368–417 extracted from a pheochromocytoma is phosphorylated by H. Dahma; P. Gourlet; A. Vandermeers; M-C Vandermeers-Piret; P. Robberecht (1491-1499).
A rabbit antiserum was raised against a synthetic peptide corresponding to residues 403 to 417 of human chromogranin B. This peptide was chosen to match the potential C-terminal end of a putative proteolytic fragment of the protein located between dibasic doublets in positions 366–367 and in positions 418–419 of the precursor. A radioimmunoassay based on this antiserum was developed and used to detect the protein or a fragment thereof in a pheochromocytoma tumor extract. One fragment was purified to homogeneity by successive reverse-phase HPLC chromatographies. The N-terminal sequence established by automated Edman degradation, was N-Y-P-S-L-E-L-D-K-M-A-H-G-Y-G-E-E-S-E-E-E-R corresponding to the 368–389 sequence of human chromogranin B. Taking into account the specificity of the antiserum used for peptide identification and alignment with the precursor sequence, we deduced that the purified peptide was chromogranin B (368–417) and represented a new peptide generated by limited proteolysis of chromogranin B. Combining electrospray mass-spectrometry and enzymatic dephosphorylation, we demonstrated that this peptide was phosphorylated.
Keywords: Chromogranin B; Phosphorylation; Mass-spectrometry; Pheochromocytoma;
Central galanin and N-terminal galanin fragment induce c-Fos immunoreactivity in the medulla oblongata of the anesthetized rat by P Marcos; Z Dı́az-Cabiale; M.P Cordón; R Coveñas; N Yanaihara; K Fuxe; S González-Barón; J.A Narváez (1501-1509).
This immunohistochemical study analyzed the c-Fos expression (c-Fos-ir) induced by galanin injections. Galanin and N-terminal galanin fragment (1–15) induced a significant increase of c-Fos expression (c-ir) within the medulla oblongata 90 min and 6 h. after intracisternal injections. This expression has been studied mainly in the nucleus of the solitary tract and in the ventrolateral medulla showing different temporal profiles for both peptides. The presence of c-Fos-ir in TH-positive cells was analyzed in all the groups. These results may be relevant to understand the role of galanin in several functions including central cardiovascular control.
Keywords: Galanin; Galanin fragment; c-Fos; Medulla oblongata; Rat; Brain;
Human fibrinopeptide A mediates allergic reaction in mice in the acute phase by Yutaka Masuda; Toshihiro Sugiyama (1511-1513).
We detected a human humoral peptide that deglycosylates mouse antibody IgE, and found that this peptide had the amino acid sequence ADSGEGDFLAEGGGV. The peptide synthesized according to the sequence also deglycosylated the antibody IgE. The deglycosylated IgE did not induce mouse systemic anaphylaxis. Human fibrinopeptide A has the amino acid sequence indicated above, and a polypeptide extracted from human urine showed an antiallergic effect on humans and mice, which strongly suggests that fibrinopeptide A mediates allergic reaction via antibody IgE-deglycosylation, and is excreted as a polypeptide in urine.
Keywords: Allergic reaction; Human fibrinopeptide A; Antibody IgE; Glycosylation; Polypeptide extracted from urine;