Biomedical subjects

H Vaudry

Publications and source records attributed to H Vaudry.

At least 289 records · Page 16Linked to original sources

PubMed1994

Pituitary adenylate cyclase-activating peptide (PACAP) immunolocalization in lymphoid tissues of the rat.

Pituitary adenylate cyclase activating peptide (PACAP) is a novel peptide isolated from the ovine hypothalamus. PACAP exists in 2 molecular forms with 27 (PACAP27) or 38 (PACAP38) amino acid residues. PACAP localization was studied by immunohistochemical methods in central (bone marrow and thymus) and peripheral (spleen, lymph nodes and duodenal mucosa) lymphoid tissues with antisera raised against PACAP27 or PACAP38. PACAP-positive cells were found in all lymphoid tissues examined. These cells were highly positive for PACAP38 but were negative for PACAP27. Morphologically, they were small mononuclear cells with relatively scarce cytoplasm and lymphocyte-like features. PACAP38-positive cells were abundant in peripheral lymphoid tissues (i.e., mesenteric lymph nodes). In the duodenal mucosa, PACAP38-positive cells were located either in the lamina propria or epithelium. These results suggest that PACAP38-positive cells are present within lymphoid tissues and may represent a lymphocyte-like cell subpopulation that has a potential role in cell-to-cell interactions in the immune system and in the integrated communication between neuroendocrine and immune systems.

Animals↗

PubMed1994

Isolation and characterization of peptides derived from the cleavage of the cytoplasmic domain of synaptophysin in frog brain.

Three overlapping peptides have been isolated from the whole brain of the European green frog, Rana ridibunda and identified as fragments of the cytoplasmic domain of the synaptic vesicle membrane protein, synaptophysin. The primary structures of the peptides define the amino acid sequence of the 58 residues at the COOH-terminus of the protein and indicate that fragments arose from proteolytic cleavages at the COOH-terminal side of aspartyl residues. The overall conservation of structure of the cytoplasmic domain between the mammalian and amphibian proteins is relatively poor (58% sequence identity between frog and rat synaptophysin). However, the pattern of repeating tyrosine residues that is present in mammalian and Torpedo synaptophysins is also found in the frog protein suggesting that this structural motif is necessary for the, as yet unknown, function of the protein. The cytoplasmic region of frog synaptophysin is also rich in glutamine and glycine residues, but the putative consensus repeating sequence Tyr-Gly-Pro/Gln-Gln-Gly in mammalian synaptophysins does not occur in the frog protein. The data raise the possibility that synaptophysin, like the chromogranins and secretogranin II, may function as the precursor of biologically active peptides.

Amino Acid Sequence↗

PubMed1994

Distribution of FMRFamide-like immunoreactivity in the brain of the lizard Podarcis sicula.

The distribution of FMRFamide-like immunoreactive peptides was investigated in the brain of the lizard, Podarcis sicula, using the indirect immunofluorescence technique. The main populations of FMRFamide-immunoreactive cell bodies were located in the forebrain. In the telencephalon, FMRFamide-containing neurons were found both in the pallium and subpallium, namely in the medial cortex, the anterior olfactory nucleus, the nucleus accumbens, the septal nuclei, the nucleus of the medial forebrain bundle, and the nucleus of the diagonal band of Broca. In the diencephalon, a dense accumulation of FMRFamide-immunoreactive neurons was observed in the area preoptica lateralis, the nucleus suprachiasmaticus, the nucleus periventricularis hypothalami, the area lateralis hypothalami, and the dorsal region of the nucleus geniculatus lateralis. In the midbrain, sparse immunoreactive perikarya were found in the tegmentum of the mesencephalon. FMRFamide-immunoreactive fibers were visualized in all regions containing positive cell bodies. In particular, dense bundles of immunoreactive processes were seen in the area preoptica lateralis, in the hypothalamus, and in the median eminence. The tectum and the basal mesencephalon were also densely innervated. Conversely, the caudal brain stem only exhibited scarce immunoreactive processes. The distribution pattern of FMRFamide-immunoreactive neurons in the brain of Podarcis sicula exhibits a number of similarities with that reported in mammals, but significantly differs from that reported in amphibians and fish, suggesting that the neuromodulatory functions of FMRFamide may have diverged during the emergence of terrestrial life.

Age Factors↗

PubMed1994

Modulation of the biological activity of thyrotropin-releasing hormone by alternate processing of pro-TRH.

Thyrotropin-releasing hormone prohormone contains multiple copies of TRH linked together by connecting sequences. Like other plurifunctional prohormone proteins, pro-TRH undergoes differential proteolytic processing in various tissues to generate, beside authentic TRH, several other novel peptides corresponding to C-terminally extended forms of TRH and connecting fragments. The pro-TRH connecting peptides are, together with TRH, predominant storage forms of TRH-precursor related peptides in the rat hypothalamus. Connecting peptides are co-localized with TRH in the median eminence nerve endings and co-released through a mechanism involving voltage-operated Ca2+ channels. The connecting peptide Ps4 is involved in potentiation of the action of TRH on thyrotropin hormone release by pituitary in vitro and in vivo through interactions with a specific pituitary cell receptor coupled to dihydropyridine and omega-connotoxin sensitive Ca2+ channels of the L-type. It also causes dose-dependent increases in the steady state levels of mRNAs of TSH and prolactin through stimulation of the respective gene promoter activities. These findings indicate that Ps4 and TRH, two peptides which originate from a single multifunctional biosynthetic precursor, can function on the same target tissues in a coordinate manner to promote hormonal secretion. This suggests that differential processing of the TRH prohormone may have the potential to modulate the biological activities of TRH.

Amino Acid Sequence↗

PubMed1994

Quantitative autoradiographic study of somatostatin receptors in the adult human cerebellum.

The evolution of the distribution and density of somatostatin receptors was studied in the human cerebellum during ageing. The brain tissues were collected 3-30 h after death from 20 individuals aged from 28 to 86 years. In vitro autoradiographic experiments were performed on blocks of vermis and of right and left cerebellar hemispheres, using [125I-Tyr0,DTrp8]S14 as a radioligand. In the vermis, the mean concentrations of somatostatin receptors in the molecular layer, the granular layer and the medulla were 140 +/- 9, 150 +/- 22 and 61 +/- 13 fmol/mg proteins, respectively. For each individual, the density of sites in the two lateral lobes was similar. The mean concentrations of somatostatin receptors in the molecular layer, the granular layer and the medulla were 152 +/- 17, 190 +/- 20 and 56 +/- 11 fmol/mg proteins, respectively. The mean level of somatostatin receptors and the type of distribution of the receptors were not correlated to the age of the patients. Different distribution patterns of somatostatin receptors were noted among the patients studied. In the majority of patients (11/20), the density of somatostatin receptors was higher in the granular layer than in the molecular layer. Conversely, in four patients, the density of somatostatin receptors was higher in the molecular layer. The other individuals exhibited similar concentrations of somatostatin receptors in the granular and molecular layers. The present study indicates that the adult human cerebellum contains a high concentration of somatostatin receptors (> 100 fmol/mg proteins) and that the receptor level does not decline during ageing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

In vitro study of the effect of urotensin II on corticosteroid secretion in the frog Rana ridibunda.

Urotensin II is a cyclic dodecapeptide that was originally isolated from the fish urophysis, the terminus of a neurosecretory system located in the caudal area of the spinal cord. We have recently isolated and characterized urotensin II in the brain of a tetrapod, the frog Rana ridibunda. Recent reports, suggesting that urotensin II may stimulate cortisol secretion in fish, prompted us to investigate the possible effects of fish and frog urotensin II on corticosteroid secretion in amphibians. Exposure of perifused frog adrenal slices to goby (Gillichthys mirabilis) urophysis extracts induced a marked stimulation of corticosterone and aldosterone secretion. In contrast, at concentrations ranging from 10(-10) to 10(-6) M, synthetic goby urotensin II had no effect on corticosteroid production. Similarly, infusion of synthetic frog urotensin II (10(-10) to 10(-6) M) did not modify the spontaneous release of corticosterone and aldosterone. In addition, frog urotensin II had no effect on ACTH- and angiotensin II-induced secretion of corticosteroids. These results show that in frog, urotensin II does not modulate spontaneous and ACTH- or angiotensin II-evoked adrenal steroidogenesis.

Adrenal Cortex Hormones↗

PubMed1994

Involvement of the cytoskeleton in the mechanism of action of endothelin on frog adrenocortical cells.

In a previous report, we have shown that endothelin-1 (ET-1) is a potent stimulator of corticosterone and aldosterone secretion by frog adrenocortical cells. In the present study, we examine the possible involvement of cytoskeletal elements in the mechanism of action of ET-1 on corticosteroid secretion from frog adrenal gland. The microfilament disrupting agent cytochalasin B (5 x 10(-5) M) induced a reversible inhibition of the spontaneous secretion of corticosteroid and blocked the response of adrenocortical cells to ET-1 (5 x 10(-9) M). In contrast, the antimicrotubular agent vinblastine (10(-5) M) and the intermediate filament inhibitor beta-beta' iminodipropionitrile (10(-3) M) had virtually no effect on both spontaneous and endothelin-induced steroidogenesis. Taken together, these results indicate that, in the frog adrenal gland, the integrity of the microfilament network is required for the corticotropic activity of ET-1 whereas microtubules and intermediate filaments are apparently not involved in the mechanism of action of ET-1.

Adrenal Cortex↗

PubMed1994

Characterization of the GABA-induced current in frog pituitary melanotrophs.

The molecular mechanisms regulating GABAA receptor activity in cultured frog melanotrophs were studied using the patch-clamp technique. In the whole-cell configuration, application of GABA evoked a dose-related increase of inward chloride currents. The ED50 value, estimated from the sigmoidal dose-response curve was 2 x 10(-6) M and the Hill coefficient was 1.55. The amplitude of the GABA-induced current decayed with time. Kinetics analysis of the desensitization revealed that the time-course of the current decrement was fitted by one exponential. Graded doses of GABA or association of GABA with the benzodiazepine receptor agonist flunitrazepam accelerated the desensitization process. In contrast, the time-course of the current did not significantly vary at different holding potentials. In the outside-out configuration, GABA was found to activate channels which displayed three unitary conductance levels (8, 15 and 30 pS). The channel openings of the more frequent conductance level (30 pS) exhibited short and long lasting open states (1.2 and 28.3 ms at -60 mV). Altogether these data reveal that frog melanotrophs possess a single population of GABAA receptors which interconvert into a higher affinity state in the presence of benzodiazepine receptor agonists. Two GABA molecules must bind to the receptor to trigger long lasting channel openings. In addition, the activity of the GABAA receptor appears to be independent of the accumulation of intracellular chloride ions.

Animals↗

PubMed1994

The secretion of alpha-MSH from xenopus melanotropes involves calcium influx through omega-conotoxin-sensitive voltage-operated calcium channels.

The secretory activity of endocrine cells largely depends on the concentration of free cytosolic calcium. We have studied the mechanisms that are involved in supplying the calcium necessary for the secretion of alpha-melanophore-stimulating hormone (alpha-MSH) from melanotrope cells in the pituitary intermediate lobe of the amphibian Xenopus laevis. Using whole-cell voltage clamp, high-voltage activated calcium currents were observed, with a peak current between 0 and +20 mV. Two types of Ca(2+)-currents appeared, depending on the experimental setup. An inactivating current, which was observed after a 10 msec depolarizing prepulse, resembled currents through N-type channels as it was clearly inhibited by 1 microM omega-conotoxin. The second type was a non-inactivating current, which was blocked up to 50% by 1 microM nifedipine, indicating its L-type nature. Only a small component of this inactivating current could be blocked by omega-conotoxin. No evidence was found for the presence of transient, low-voltage activated currents. The spontaneous secretion of alpha-MSH from superfused neurointermediate lobes was dependent on extracellular calcium, as low calcium conditions (10(-4)-10(-8) M) rapidly inhibited this process. Under these conditions, secretion was not affected by depolarizing concentrations of potassium chloride. The calcium ionophore A23187 increased secretion under low calcium conditions, but had no effect on spontaneous alpha-MSH release. These results suggest that spontaneous alpha-MSH release depends on influx of calcium through voltage-operated calcium channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Effects of selective disruption of cytoskeletal elements on steroid secretion by human adrenocortical slices.

The role of the cytoskeleton in corticosteroid secretion in normal human adrenal gland was investigated in vitro, using the perifusion technique and confocal laser scanning microscopy. Vinblastine, which selectively disrupted microtubules in adrenocortical cells, did not modify the basal release of cortisol but induced a 58% inhibition of the response to adrenocorticotropic hormone (ACTH). In contrast, vinblastine did not alter dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP)-induced steroid secretion. Cytochalasin B treatment caused disappearance of microfilaments and blocked the stimulatory action of ACTH and DBcAMP on cortisol secretion. beta,beta'-Iminodipropionitrile disorganized the cytokeratin intermediate filaments but did not alter spontaneous and ACTH-evoked cortisol release. These results, which provide the first evidence for an action of cytoskeleton inhibitors on cortisol release from normal human adrenocortical cells, show that microtubules are involved in the mechanism of action of ACTH at a step preceding adenosine 3',5'-cyclic monophosphate formation, whereas microfilaments are involved in a late and common step of adrenal steroidogenesis.

Adrenal Cortex↗

PubMed1994

Adrenaline induces hyperpolarization in frog pituitary melanotrophs through activation of potassium channels.

A patch-clamp study was conducted on cultured frog pituitary melanotrophs, in order to investigate the effects of adrenaline on the electrical activity of these cells. In the whole-cell configuration, adrenaline (1 microM) caused hyperpolarization that was accompanied by a fall in membrane input resistance and a blockage of spontaneous action potentials. Under voltage clamp, adrenaline elicited a net-outward current. The hyperpolarization became undetectable at a command voltage of -100 mV which corresponded to the equilibrium potential of potassium ions. The effect of adrenaline on membrane potential and spontaneous activity was blocked by the alpha 2-adrenergic receptor antagonist yohimbine (1-10 microM) but could not be mimicked by the alpha 2-adrenergic agonist clonidine (1-10 microM). In the cell-attached configuration, exposure of the extra-patch membrane to adrenaline increased the occurrence of single-channel currents with a slope conductance of 100 pS. The deduced reversal potential of these currents corresponded to the equilibrium potential of potassium ions. These results suggest that frog melanotrophs display an alpha 2-adrenergic receptor subtype coupled to potassium channels involved in hyperpolarization.

Adrenergic alpha-Antagonists↗

PubMed1994

Morphological and functional heterogeneity of frog melanotrope cells.

Previous reports have described the heterogeneity of different pituitary cell types on the basis of morphological and physiological criteria. In the present study, we investigated the possible existence of distinct subpopulations of melanotrope cells in the intermediate lobe of the pituitary of the frog, Rana ridibunda. Separation of dispersed pars intermedia cells in a Percoll density gradient made it possible to isolate two fractions of melanotrope cells whose morphological and functional properties were further characterized. Analysis of the relative volume and number of various cellular organelles showed that high-density cells had a larger number of secretory granules than low-density cells. Concurrently, radioimmunoassay quantification revealed that the concentration of alpha-melanocyte-stimulating hormone (alpha-MSH) was 2 times higher in the heavy cell population. The rate of secretion of alpha-MSH from cultured melanotrophs was significantly higher in low-density than in high-density cells. Thyrotropin-releasing hormone (TRH) was more potent in stimulating alpha-MSH release from the low-density than from the high-density cell subset. In contrast, the response to TRH persisted for a longer time in the high-density cell subpopulation. Taken together, these data demonstrate the existence of two subpopulations of melanotrope cells, and indicate that the low-density cells have a secretory rate substantially greater than high-density cells.

Animals↗

PubMed1994

Localization, identification, and action of calcitonin gene-related peptide in the frog adrenal gland.

The localization of calcitonin gene-related peptide (CGRP)-like immunoreactivity in the adrenal gland of the frog, Rana ridibunda, was examined by the indirect immunofluorescence technique. Using an antiserum directed against rat alpha-CGRP, the presence of a network of positive fibers was observed in the adrenal parenchyma. The immunoreactive material has been characterized by HPLC analysis combined with RIA quantification. The elution profile revealed the existence of a single form of CGRP exhibiting the same retention time as synthetic frog CGRP. The possible involvement of CGRP in the regulation of corticosteroid secretion was studied in vitro using a perifusion system for frog adrenal slices. Graded doses of frog CGRP (from 3 x 10(-9) to 3 x 10(-6) M) increased corticosterone and aldosterone secretion in a dose-dependent manner (ED50, 4.1 x 10(-8) M). Several other forms of CGRP, i.e. rat alpha-CGRP and beta-CGRP, and human alpha-CGRP and beta-CGRP, were also capable of enhancing steroid output, but frog CGRP was the most effective stimulator of steroidogenesis. Repeated administration of rat alpha CGRP induced a reproducible stimulation of corticosteroid secretion without any tachyphylaxis. Prolonged infusion of the peptide (3 h) caused a rapid increase in corticosteroid release, followed by a gradual decline of steroid secretion, suggesting the occurrence of a desensitization phenomenon. Rat alpha-CGRP also gave rise to a significant increase in corticosteroid release from acutely dispersed adrenal cells. These results show the presence of CGRP in fibers innervating the frog adrenal gland. The data also demonstrate that synthetic CGRP exerts a direct stimulatory effect on corticosteroid secretion. Taken together, these findings suggest that CGRP, released by nerve fibers in the adrenal tissue, can locally regulate corticosteroid secretion.

Adrenal Cortex Hormones↗

PubMed1994

Pituitary adenylate cyclase-activating polypeptide stimulates both adrenocortical cells and chromaffin cells in the frog adrenal gland.

In a previous report, we have shown that frog pituitary adenylate cyclase-activating polypeptide (fPACAP38) is a potent stimulator of corticosteroid secretion by frog adrenal slices in vitro. The aim of the present study was to determine the mode of action of PACAP on the frog adrenal gland. Immunoelectron microscopic labeling revealed that PACAP-like immunoreactivity is present in electron-dense vesicles within nerve endings located in the vicinity of both adrenocortical and chromaffin cells. Exposure of dispersed adrenal cells to fPACAP38 caused stimulation of corticosteroid secretion. Labeling of cultured adrenal cells with [125I]PACAP27 revealed the existence of PACAP-binding sites on both adrenocortical and chromaffin cells. Saturation and competition experiments showed the occurrence of high affinity and selective receptors for fPACAP38 on cultured adrenal cells. fPACAP38 (10(-8)-10(-5) M) provoked a dose-dependent stimulation of cAMP production by frog adrenal slices. Microflurimetric studies demonstrated that fPACAP38 induced a substantial elevation of the intracellular calcium concentration in both adrenocortical and chromaffin cells. The present results indicate that in the frog adrenal gland, PACAP fibers innervate both adrenocortical and chromaffin cells. The data show the presence of PACAP receptors on the two cell types. PACAP exerts a direct stimulatory effect on corticosteroid-producing cells. This effect is probably mediated through stimulation of adenylyl cyclase activity and/or augmentation of intracellular Ca2+. PACAP also increases intracellular Ca2+ in chromaffin cells. These data suggest that PACAP, released locally in the adrenal gland, acts as a neuroendocrine factor, regulating the activity of adrenocortical and chromaffin cells.

Adrenal Cortex↗

PubMed1994

Visualization of gamma-aminobutyric acid A receptors on proopiomelanocortin-producing neurons in the rat hypothalamus.

It has recently been shown that gamma-aminobutyric acid (GABA) and central-type benzodiazepine receptor agonists inhibit the expression of the POMC gene and the release of POMC-derived peptides from hypothalamic neurons. To determine whether the inhibitory effect of GABA could be accounted for by a direct action on POMC neurons, we investigated the localization of the beta 1-subunit of the GABAA-benzodiazepine-receptor complex in the arcuate nucleus. Using a monoclonal antibody raised against a synthetic fragment of the beta 1-subunit, we demonstrate the presence of GABAA receptor on POMC neurons. The proportion of POMC neurons that exhibit immunoreactivity for the beta 1-subunit of the GABAA receptor was not significantly different in the posterior portion (73.0-76.0%) and anterior portion (61.3-62.7%) of the arcuate nucleus. The data also revealed that in the arcuate nucleus, a majority of neurons that were immunostained by the antibody to the beta 1-subunit were not POMC positive. The present results support the concept that GABAA and central-type benzodiazepine receptor agonists exert a direct inhibitory action on POMC neurons. The data also indicate the existence of subsets of POMC neurons within the arcuate nucleus.

Amino Acid Sequence↗

PubMed1994

Somatostatin and pituitary adenylate cyclase-activating polypeptide (PACAP): two neuropeptides potentially involved in the development of the rat cerebellum.

Somatostatin and pituitary adenylate cyclase-activating polypeptide (PACAP) have been originally isolated from the ovine hypothalamus on the basis of their hypophysiotropic activities. There is now evidence that somatostatin and PACAP may play a role in the development of the central nervous system, particularly in the cerebellum. High concentrations of somatostatin and somatostatin receptors have been detected in the rat cerebellum during the first two postnatal weeks. Somatostatin binding sites are associated with a germinative matrix, the external granule cell layer, which generates the majority of the interneurons of the cerebellum. By using immature granule cells in primary culture, we could demonstrate that somatostatin binding sites are actually expressed by neuroblasts and correspond to authentic receptors negatively coupled to adenylate cyclase. Concurrently, studies on the distribution of PACAP receptors in the immature rat cerebellum showed the presence of a high concentration of binding sites in the external granule cell layer during the first two postnatal weeks. Pharmacological characterization of these binding sites showed that they correspond to type I PACAP receptors positively coupled to adenylate cyclase. The concomitant and transient expression of somatostatin and PACAP receptors by cerebellar neuroblasts in the external granule cell layer suggests that the two neuropeptides may be involved in the regulation of multiplication, migration and/or differentiation of neuroblasts. This hypothesis is also supported by the actions of somatostatin and PACAP on various transduction systems. In particular, the opposite effects of the two neuropeptides on adenylate cyclase activity suggest that somatostatin and PACAP may exert antagonistic actions.

Animals↗

PubMed1994

A cryptic peptide of TRH prohormone inhibits TRH-induced GH release.

The effects of two cryptic peptides from pro-TRH: Ps4 (160-169) and Ps5 (178-199) were investigated on basal and secretagogue (GRH and TRH)-induced releases of GH from perifused fragments of rat adenohypophysis. Validation of the perifusion system was done by measuring: (1) the dose-dependent effect of GRH and TRH on GH release; and (2) the stimulation of that release by forskolin (to mimic the adenylate cyclase pathway) or by phorbol ester (to mimic the protein kinase C pathway). We show that: (1) Ps4 and Ps5 (1 microM) do not modify basal GH release; (2) Ps4 (1 microM) changes neither GRH (10 nM)- nor TRH (100 nM)-induced release of GH; (3) Ps5 (100 nM and 1 microM) significantly decreases the release of GH induced by equimolar concentrations of TRH but not that induced by GRH.

Animals↗

PubMed1994

Immunocytochemical localization and biological activity of 3 beta-hydroxysteroid dehydrogenase in the central nervous system of the frog.

The enzyme 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) catalyzes biosynthesis of progesterone (P) and all precursors of glucocorticoids, mineralocorticoids, androgens, and estrogens. Despite the broad interest raised by neurosteroids, the cellular localization of 3 beta-HSD has never been investigated in the brain. We took advantage of the availability of an antiserum raised against human placental 3 beta-HSD to determine the distribution of 3 beta-HSD-immunoreactive structures in the brain of the frog Rana ridibunda by the indirect immunofluorescence technique. Three populations of 3 beta-HSD-immunoreactive cell bodies were observed in the hypothalamus, namely, in the rostral region of the preoptic nucleus, the dorsal infundibular nucleus, and the dorsal part of the ventral infundibular nucleus. A dense network of 3 beta-HSD-immunoreactive nerve fibers was visualized in the dorsal area of the diencephalon, that is, in the lateral neuropil, the corpus geniculatus lateralis, and the nucleus posterolateralis thalami. Reversed-phase HPLC analysis of frog hypothalamic extracts combined with RIA detection showed the presence of substantial amounts of immunoreactive steroids coeluting with P and 17-hydroxyprogesterone (17OH-P). The synthesis of delta 4-3-keto-steroids in the frog hypothalamus was investigated using the pulse-chase technique with 3H-pregnenolone (3H-delta 5P) as a precursor. The formation of five tritiated metabolites of 3H-delta 5P was observed, one of which coeluted with 17OH-P. Conversion of 3H-delta 5P into this radioactive metabolite was significantly reduced by trilostane, a specific inhibitor of 3 beta-HSD. Immunodetection of newly synthesized steroids in HPLC fractions of hypothalamic extracts, using 17OH-P antibodies, revealed the existence of an immunoreactive steroid that exhibited the same retention time as synthetic 17OH-P. The present study provides the first immunocytochemical mapping of 3 beta-HSD, a key enzyme of the steroid biosynthetic pathway, in the CNS of a vertebrate. The data also demonstrate for the first time biosynthesis of neurosteroids in the brain of a nonmammalian vertebrate.

17-alpha-Hydroxyprogesterone↗