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H Vaudry

Publications and source records attributed to H Vaudry.

At least 613 records · Page 34Linked to original sources
PubMedDate not supplied

Localization and characterization of the N-terminal fragment of atrial natriuretic factor (ANF) precursor in the frog heart.

The localization of the N-terminal fragment of the atrial natriuretic factor (ANF) precursor in the heart of the frog Rana ridibunda was examined by the indirect immunofluorescence and the immunogold techniques using an antiserum directed against synthetic rat ANF (Asp11-Ala37). At the optic level, positive material was found in most atrial myocytes. Staining of consecutive sections of frog heart with antibodies against N-terminal and C-terminal regions of the proANF molecule showed that both peptides are contained in the same cardiocytes. In the rat atrium, antibodies against the N-terminal ANF region induced a more intense labeling than in the frog atrium. Electron microscopic studies indicated that all secretory granules present in frog atrial cardiocytes contain N-terminal ANF-like immunoreactive material. The positive material localized in frog atrium was characterized by gel filtration and radioimmunological detection. Serial dilutions of frog atrial extracts exhibited displacement curves which were parallel to that obtained with synthetic human ANF (Asn1-Asp30). Sephadex G-50 gel chromatography of the immunoreactive material showed that the N-terminal ANF-like immunoreactivity eluted in a single peak corresponding to high molecular weight material. These results indicate that the N-terminal fragment of frog proANF is immunologically and biochemically related to the homologous mammalian peptide.

Animals↗
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Immunoelectron microscopic localization of thyrotropin-releasing hormone (TRH) precursor in the rat raphe nuclei.

Using antisera to two pro-thyrotropin-releasing hormone (pro-TRH)-derived cryptic peptides, we have studies by immunocytochemistry the ultrastructural localization of pro-TRH in the rat raphe nuclei. The same results were obtained with both antisera. Immunostaining was found in cell bodies, dendrites and endings. In cell bodies, the reaction product was restricted to Golgi saccules and dense core vesicles which were very few in number. In dendrites, the staining was rather diffuse without any association with specific organelles. These results suggest that the Golgi apparatus might be involved in pro-TRH processing.

Amino Acid Sequence↗
PubMedDate not supplied

Localization of atrial natriuretic factor (ANF)-related peptides in the central nervous system of the elasmobranch fish Scyliorhinus canicula.

We have investigated the localization of atrial natriuretic factor (ANF)-like immunoreactivity in the central nervous system of the cartilaginous fish, Scyliorhinus canicula, using the indirect immunofluorescence technique. Immunoreactive perikarya and fibers were observed in two regions of the telencephalon, the area superficialis basalis and the area periventricularis ventrolateralis. In the diencephalon, the hypothalamus exhibited a moderate number of ANF-containing neurons and fibers located in the preoptic and periventricular nuclei and in the nucleus lateralis tuberis. The most important group of ANF-immunoreactive cells was observed in the nucleus tuberculi posterioris of the diencephalon. In contrast, the mesencephalon showed only a few ANF-positive nerve processes located in the tegmentum mesencephali. Numerous fine fibers and nerve terminals were found in the dorsal area of the neurointermediate lobe of the pituitary. These results provide the first evidence for the presence of ANF-related peptides in the brain of a cartilaginous fish. The widespread distribution of ANF-positive cells and fibers in the brain and pituitary suggests that this peptide may act both as a neurotransmitter and (or) a neurohormone in fish.

Animals↗
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Immunohistochemical mapping of galanin-like immunoreactivity in the brain of the dogfish Scyliorhinus canicula.

The distribution of galanin-like immunoreactivity in the brain of the dogfish Scyliorhinus canicula was investigated using the indirect immunofluorescence technique. In the telencephalon, positive cells and fibers were located in the mid-caudal part of the area superficialis basalis, the n. septi caudoventralis and in the n. interstitialis commissurae anterioris. Most of the galanin-containing neurons observed in the hypothalamus were located in the magnocellular preoptic nucleus. Positive perikarya were also found in the n. lobi lateralis hypothalami and in the n. lateralis tuberis. A dense network of positive nerve processes was noted in the caudal part of the median eminence. In the dorso-caudal part of the diencephalon numerous immunoreactive neurons were seen in the recessus posterioris. A large bundle of galanin-containing fibers, which divided in two branches, was observed in the basal midbrain tegmentum. The widespread distribution of galanin-like material suggests that, in the dogfish, galanin may be involved in various brain functions including neuroendocrine regulations.

Animals↗
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Intracerebroventricular injection of arginine vasotocin induces elevation of blood pressure in anesthetized trout.

The present investigation assessed the ability of the neurohypophysial nonapeptide arginine vasotocin (AVT) to centrally regulate the cardiovascular activity in fish. Intracerebroventricular (ICV) injection of AVT (0.4 to 50 ng/kg b.wt.) in anesthetized trout resulted in a dose-related increase in blood pressure (BP) without any consistent changes in heart rate. For doses of AVT ranging from 2 to 50 ng/kg b.wt., BP remained elevated during at least 25 min after ICV injection. Systemic (intraarterial) administration of the same doses of AVT appeared to be less efficient than ICV injection, except for the highest dose (50 ng/kg) which evoked a similar rise in BP as that observed after ICV administration. In contrast to AVT, a high concentration of neuropeptide Y (10 micrograms/kg b.wt., ICV) caused only a slight increase of BP. The results suggest that AVT acts centrally to regulate BP in fish. These data, together with the widespread distribution of AVT-immunoreactive fibers and AVT binding sites in the brain, support the notion that, in fish, AVT may play neuromodulator and/or neurotransmitter functions.

Animals↗
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Increased brain content of the endogenous benzodiazepine receptor ligand, octadecaneuropeptide (ODN), following portacaval anastomosis in the rat.

Evidence suggests that endogenous benzodiazepine receptor ligands such as diazepam binding inhibitor (DBI) and its metabolite octadecaneuropeptide (ODN) may be implicated in the pathogenesis of hepatic encephalopathy. Using an immunocytochemical technique and an antibody of high specific activity to synthetic ODN, we studied the effects of portacaval anastomosis (PCA) on ODN distribution in rat brain. Four weeks after PCA, ODN immunolabeling was increased in several brain regions including cerebral cortex, hippocampus, hypothalamus and thalamus. Increased ODN immunolabeling was confined to nonneuronal elements such as astrocytes and ependymal cells. Neuropathological evaluation of brain following PCA reveals astrocytic rather than neuronal changes. These results are consistent with a role for endogenous neuropeptide ligands for astrocytic benzodiazepine receptors in the pathogenesis of hepatic encephalopathy.

Animals↗
PubMedDate not supplied

Distribution of FMRFamide-like immunoreactivity in the brain of the elasmobranch fish Scyliorhinus canicula.

The distribution of FMRFamide-like-immunoreactive peptides was investigated in the brain and pituitary of the elasmobranch fish Scyliorhinus canicula using the indirect immunofluorescence technique. FMRFamide-immunoreactive cells and fibers were mainly observed in the telencephalon and the diencephalon, while other brain structures were almost unstained. In the telencephalon, FMRFamide-like-containing neurons were seen in the caudal part of the area periventricularis pallialis, in the posterior area of the nucleus septi medialis and in the nucleus septi caudoventralis. In the diencephalon, numerous FMRFamide-positive cell bodies were observed in the hypothalamus, ventral thalamus and posterior tuberculum. The highest density of immunofluorescent perikarya was found in the nucleus lobi lateralis hypothalami and in the nucleus periventricularis hypothalami. More caudally, the mesencephalon and the caudal brainstem only contained scattered varicose FMRFamide-immunoreactive fibers. Stained fibers were also identified in the median eminence and several FMRFamide-like-positive cells were detected in the dorsal and rostral parts of the neurointermediate lobe of the pituitary. These data indicate that substances related to the molluscan cardioexcitatory peptide FMRFamide are widely distributed in the brain of S. canicula, suggesting their implication in neuroendocrine and/or neuromodulatory functions.

Amino Acid Sequence↗
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Characterization of endozepine-related peptides in the central nervous system and in peripheral tissues of the rat.

Endozepines represent a novel family of regulatory peptides that have been isolated by their ability to displace benzodiazepines from their binding sites. All endozepines derive from an 86 amino acid precursor polypeptide called diazepam binding inhibitor (DBI), which generates, through proteolytic cleavage, several biologically active endozepines. The aim of the present study was to compare the molecular forms of endozepines present in different regions of the rat brain and in various peripheral organs using an antiserum raised against the central (biologically active) region of DBI. Combination of HPLC analysis and RIA detection revealed the existence of two major forms (peaks I and II) of endozepine-immunoreactive peptides. The retention times of the two peaks (36 and 39 min, respectively) were identical in all tissues or organs tested. Western blotting analysis of cerebral cortex extracts confirmed the existence of two immunoreactive species with apparent molecular weights 4000 and 6000 Da, which respectively correspond to peaks I and II. Tryptic digestion of peaks I and II generated a single immunoreactive peptide that coeluted with the synthetic octadecaneuropeptide ODN [DBI(33-50)]. These results show that, in different parts of the brain and in various peripheral organs, DBI is rapidly processed to generate two peptides of apparent molecular weight of 4000 and 6000 Da, which both possess the biologically active determinant of endozepines.

Animals↗
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Distribution and characterization of endozepine-like immunoreactivity in the central nervous system of the frog Rana ridibunda.

The localization of endozepine-like immunoreactivity in the brain of the frog Rana ridibunda was investigated by indirect immunofluorescence, using an antiserum against synthetic rat octadecaneuropeptide (ODN). A specific immunoreaction was detected in ependymal cells lining the ventricular system of the brain and in circumventricular organs. Numerous immunoreactive cells were found covering the walls of the lateral ventricles in the telencephalon, as well as in the diencephalic and mesencephalic ventricles. In the hypothalamus, both the preoptic nucleus and the infundibular region showed numerous immunopositive cells. Ependymal cells lining the rhomboencephalic fourth ventricle and the central canal of the spinal cord were also immunoreactive. The concentration of endozepine-like immunoreactivity was measured in various regions of the brain using a sensitive and specific radioimmunoassay for rat ODN. The highest levels of ODN-like immunoreactivity were found in the infundibulum, cerebellum and preoptic area. Reverse phase high performance liquid chromatography and radioimmunoassay quantification were used to characterize endozepines in the frog brain. The elution profiles of the different brain regions revealed four major immunoreactive peaks. The present results demonstrate the presence of peptides immunologically related to the endozepine family in the central nervous system of the frog. The localization of immunoreactive endozepines in ependymal cells suggests that these peptides play important neuromodulatory functions in the amphibian brain.

Animals↗
PubMedDate not supplied

Primary structure of frog PYY: implications for the molecular evolution of the pancreatic polypeptide family.

A peptide belonging to the pancreatic polypeptide (PP) family was isolated in pure form from the intestine of the European green frog (Rana ridibunda). The primary structure of the peptide was established as: Tyr-Pro-Pro-Lys-Pro-Glu-Asn-Pro-Gly-Glu10-Asp-Ala- Ser-Pro-Glu-Glu-Met-Thr-Lys-Tyr20-Leu-Thr-Ala-Leu-Arg-His-Tyr-Ile- Asn-Leu30-Val - Thr-Arg-Gln-Arg-Tyr-NH2. This amino acid sequence shows moderate structural similarity to human PYY (75% identity) but stronger similarity to the PP family peptides isolated from the pancreas of the salmon (86%) and dogfish (83%). The data suggest that the two putative duplications of an ancestral PP family gene that have given rise to PP, PYY and NPY in mammals had already taken place by the time of the appearance of the amphibia. In fish, however, only a single duplication has occurred, giving rise to NPY in nervous tissue and a PYY-related peptide in both pancreas and gut.

Amino Acid Sequence↗
PubMedDate not supplied

Immunohistochemical localization of delta sleep-inducing peptide (DSIP) in the brain and pituitary of the cartilaginous fish Scyliorhinus canicula.

The distribution of delta sleep-inducing peptide (DSIP) in the brain and pituitary of the cartilaginous fish Scyliorhinus canicula was investigated using the indirect immunofluorescence technique. Delta sleep-inducing peptide-like immunoreactive cell bodies were mainly observed in the nucleus lateralis tuberis of the hypothalamus. Immunolabeled perikarya were also distributed in the nucleus lobi lateralis hypothalami and in the dorso-lateral wall of the recessus posterioris. Most of these cells, located in the subependymal layers of the infundibulum and lateral lobes, had the typical aspect of cerebrospinal fluid-contacting elements. The DSIP-like immunoreactive fibers were localized in the basal telencephalon, within the regions of the nucleus interstitialis commissurae anterioris and the nucleus entopeduncularis. A dense network of DSIP-positive fibers was seen throughout the midcaudal hypothalamus, the lateral lobes, and the posterior lobe. In the pituitary, numerous DSIP-like immunoreactive cells were detected in the median lobe of the pars distalis. In particular, a high concentration of cells was seen in the dorsal wall of the median lobe, an area which is known to contain melanin-concentrating hormone (MCH)-producing cells. Comparison of the distribution of DSIP- and MCH-like immunoreactive cells revealed that the two neuropeptides are stored in the same cells of the median lobe of the pituitary. These findings provide the first evidence for the presence of a DSIP-related peptide in fish. The distribution of the immunoreactive material supports the view that DSIP may act as a neuromodulator and/or a hypophysiotropic factor. Moreover, the presence of DSIP-like immunoreactive cells in the pars distalis suggests that this peptide may exert autocrine or paracrine effect in the pituitary.

Animals↗
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Neuroanatomical connections between corticotropin-releasing factor (CRF) and somatostatin (SRIF) nerve endings and thyrotropin-releasing hormone (TRH) neurons in the paraventricular nucleus of rat hypothalamus.

In order to investigate the possible involvement of corticotropin-releasing factor (CRF) and somatostatin (SRIF) on thyrotropin-releasing hormone (TRH) neuronal cell activity in the rat hypothalamic paraventricular nucleus, we have proceeded to the simultaneous localization of CRF or SRIF and TRH. For this purpose, we used a dual immunostaining procedure that employed antibodies to CRF and SRIF and peroxidase-labeled goat anti-rabbit IgG as a first sequence, and antibodies to a cryptic fragment (Phe178-Glu199) of pro-TRH (to label TRH neurons) and alkaline phosphatase-labeled goat anti-rabbit IgG as the second sequence. A rich innervation of the paraventricular nucleus by immunoreactive CRF and SRIF fibers was observed. A large number of CRF and SRIF nerve endings were seen intimate anatomic proximity and often appeared to surround TRH-containing cell bodies. These results strongly suggest that TRH neurons might be regulated by both CRF and SRIF. These interactions might be the neuroanatomical basis for the already observed inhibitory effects of CRF and SRIF on TRH release.

Animals↗
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Purification and characterization of joining peptide and N-terminal peptide of proopiomelanocortin from the pars distalis of the bullfrog pituitary.

The joining peptide (JP) and the N-terminal peptide of proopiomelanocortin (NPP) were isolated from an acid-acetone extract of the distal lobe of the pituitary of the bullfrog, Rana catesbeiana, and purified by gel filtration and reverse-phase high performance liquid chromatography. The amino acid sequence of the bullfrog JP resembled the sequences of the JPs of Rana ridibunda (86% similarity) and Xenopus laevis (54% similarity), as deduced from the nucleotide sequences of their cDNAs. The amino acid sequence of bullfrog NPP showed 100%, 85%, and 50% similarity with those of Rana ridibunda, Xenopus laevis, and human NPPs, respectively. Administration of bullfrog NPP (0.05-5 micrograms/ml) to perifused Rana ridibunda interrenal slices induced a dose-dependent stimulation of corticosterone and aldosterone release. The present results indicate that the primary structure of NPP has been highly conserved during evolution. These data also reveal that NPP, which has no sequence homology with ACTH, exhibits a substantial corticotropic activity.

Adrenal Cortex Hormones↗
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Isolation and structural characterization of calcitonin gene-related peptide from the brain and intestine of the frog, Rana ridibunda.

Calcitonin gene-related peptide (CGRP) was isolated in a single molecular form from an extract of the whole brain and from the small intestine of the European green frog, Rana ridibunda. The primary structure of the peptide was established as: Ala-Cys-Asn-Thr-Ala-Thr-Cys-Val-Thr-His10-Arg-Leu-Ala-Asp-Phe-Leu- Ser-Arg-Ser-Gly20-Gly-Met-Ala-Lys-Asn-Asn-Phe-Val-Pro-Thr30- Asn-Val-Gly-Ser-Ala-Phe-NH2. Frog CGRP shows only two amino acid substitutions (Val22-->Met and Gly23-->Ala) compared with chicken CGRP, as deduced from the nucleotide sequence of a cloned cDNA. The Asp14 residue, which leads to enhanced biological potency in chicken CGRP, is also present in the frog peptide. The data show that the structure of CGRP has been strongly conserved during evolution of the vertebrates.

Amino Acid Sequence↗
PubMedDate not supplied

Role of the cytoskeleton in the secretory response of the frog adrenal gland to calcitonin gene-related peptide.

We have previously shown that calcitonin gene-related peptide (CGRP) stimulates the secretion of corticosterone and aldosterone from the frog adrenal gland in vitro. The aim of the present study was to investigate the role of cytoskeletal elements in the stimulatory effect of CGRP on corticosteroid production. Perifusion of adrenal explants with the microfilament-disrupting agent cytochalasin B (5 x 10(-5) M) induced a reversible inhibition of the spontaneous secretion of corticosterone and aldosterone, and markedly reduced the stimulatory effect of frog CGRP (3 x 10(-7) M) on corticosteroid release. In contrast, administration of the antimicrotubular agent vinblastine (10(-5) M) and the intermediate filament inhibitor beta-beta' iminodipropionitrile (10(-3) M) had no significant effect on either spontaneous or CGRP-evoked steroid secretion. Taken together, these data provide the first evidence for the involvement of microfilaments in CGRP-induced corticosteroid secretion. In contrast, microtubules and intermediate filaments are not implicated in the mechanism of action of CGRP.

Adrenal Glands↗
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Mechanism of action of endothelins on adrenocortical cells.

Endothelins (ETs) play a pivotal role in the control of various endocrine and neuroendocrine tissues. In this review, we discuss the involvement of ETs as possible regulators of steroid secretion and we describe the mechanism of action of ETs on adrenocortical cells. The occurrence of ETs has been demonstrated in the human, porcine and rat adrenal gland. In humans, immunohistochemical and biochemical techniques have reported that ETs are localized exclusively in the cortex but the presence of ETs has also been detected in pheochromocytomas. In vitro studies have shown that ETs stimulate aldosterone secretion by adrenal tissues in various mammalian and amphibian animal models. The receptor subtype involved in the corticotropic action of ETs clearly differs among the various vertebrate species studied. In rat, the effect of ETs is mediated through an ET(B) receptor subtype while, in frog, an ET(A) receptor is implicated in the stimulatory action of ETs. In human adrenocortical cells, both ET(A) and ET(B) receptor subtypes are involved in the corticotropic effect of ETs. Activation of adrenal receptors causes an elevation of inositol trisphosphates associated with an increase in cytosolic calcium concentration. In addition, ETs induce an elevation of prostaglandin E2 (PGE2) and prostacyclin PGI2 production in the adrenal tissue, indicating that prostanoids may act as second messengers of ETs. It thus appears that ETs present in the adrenal gland may act as paracrine factors to stimulate the secretory activity of adrenocortical cells.

Adrenal Cortex↗
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Serotonergic regulation of adrenocortical function.

Serotonin (5-HT) plays a pivotal role in the regulation of the hypothalamo-pituitary-adrenal axis. In particular, 5-HT is involved in the stimulation of ACTH secretion during stress. Recent data indicate that, at the adrenal level, 5-HT acts as a local regulator of corticosteroid secretion. The presence of 5-HT in the adrenal gland has been demonstrated immunohistochemically and biochemically in various species including frog, mouse, rat and human. In the mouse, 5-HT has been detected in nerve fibers while, in the frog and rat, 5-HT appears to be sequestered in chromaffin cells. In man, 5-HT is stored in perivascular mast cells. In vivo and in vitro studies have shown that 5-HT stimulates mineralo- and glucocorticoid secretion from adrenal cells. In rat, the type of receptor involved in the corticotropic effect of 5-HT is still controversial. In the frog and the human, the effect of 5-HT on the adrenal cortex is mediated through a 5-HT4 receptor subtype positively coupled to adenylyl cyclase and calcium influx. Clinical studies indicate that 5-HT4 receptor agonists stimulate aldosterone secretion in healthy volunteers and in patients with aldosterone disorders. The 5-HT4 receptor agonist cisapride and angiotensin II exert additive effects on aldosterone secretion. In contrast, cisapride has no influence on ACTH-induced aldosterone release. Collectively, these findings suggest that intra-adrenal 5-HT stimulates the secretory activity of adrenocortical cells through a paracrine mode of communication involving a 5-HT4 receptor type. Serotonergic control of corticosteroid production may be involved in the physiological control of the activity of the adrenal cortex, in particular during inflammatory stress. 5-HT may also be implicated in the pathophysiology of aldosterone disorders.

Adrenal Cortex↗