Biomedical subjects

H Vaudry

Publications and source records attributed to H Vaudry.

At least 433 records · Page 24Linked to original sources

PubMed1989

Thyroid hormone regulation of neurons staining for a pro-TRH-derived cryptic peptide sequence in the rat hypothalamic paraventricular nucleus.

The influence of thyroid hormones on neurons staining for a pro-TRH-derived cryptic peptide sequence in the rat hypothalamic paraventricular nucleus was assessed by using quantitative immunocytochemistry. The antiserum used for immunocytochemical studies recognized a cryptic fragment of pro-TRH located in the Phe 178-Ser 186 region of the precursor. Hypothyroid female rats obtained following 1 month administration of 6-n-propyl-2-thiouracil (PTU) as well as euthyroid animals were treated with a low (3 micrograms/kg/day) or high (67 micrograms/kg/day) dose of L-thyroxine (T4) for 4-10 days before sacrifice. All the animals received an intraventricular injection of colchicine 2 days prior to perfusion with 4% paraformaldehyde. PTU treatment induced an increase (45% over control) in the number of immunostained neurons. The administration of a low dose of T4 to hypothyroid animals slightly increased the number of staining for a pro-TRH-derived cryptic sequence neurons, while being uneffective in euthyroid rats. In hypothyroid animals, a 4-day treatment with the high dose of T4 did not produce any changes whereas the 7-day treatment reduced the number of positive cells to 42% of control. In euthyroid rats treated with the high dose of T4 for 4 and 7 days, the number of stained neurons was reduced to 60 and 37% of control, respectively. These results indicate that thyroid hormones can modify the amounts of staining for a pro-TRH-derived cryptic sequence in hypothalamic paraventricular neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗

PubMed1989

Innervation of the pars intermedia and control of alpha-melanotropin secretion in the newt.

In this study we have investigated the presence of nerve fibers containing dopamine, thyrotropin-releasing hormone (TRH) and neuropeptide Y (NPY) in the pars intermedia of the crested newt and we have examined the possible effect of these neurohormones on the release of alpha-melanotropin (alpha-MSH) by neurointermediate lobes in vitro. By means of immunohistochemistry, we observed the presence of tyrosine hydroxylase (TH)-immunoreactive fibers in the pars intermedia of the crested newt. Using a specific antiserum to dopamine, these fibers appeared to be mainly dopaminergic in nature. Unlike anurans, urodele amphibians do not exhibit TRH or NPY-like immunoreactivity in the pars intermedia. A perifusion system technique for newt pituitaries was developed to investigate the effect of dopamine, TRH and NPY on alpha-MSH secretion. Administration of increasing concentrations of dopamine (from 10(-9) to 10(-5)M) induced a dose-related inhibition of alpha-MSH release. This inhibitory effect was mimicked by the dopamine agonist apomorphine (10(-6)M). In contrast, the secretory activity of the newt pars intermedia was not affected by administration of synthetic TRH or NPY (up to 10(-7) and 10(-6)M, respectively). These results indicate that the neurotransmitter dopamine likely plays a pivotal role in the regulation of melanotropin secretion in urodele amphibians.

Animals↗

PubMed1989

Acetylcholine stimulates alpha-melanocyte-stimulating hormone release from frog pituitary melanotrophs through activation of muscarinic and nicotinic receptors.

The release of alpha MSH from the pars intermedia of amphibians is regulated by multiple factors, including classical neurotransmitters and neuropeptides. In this study we have examined the possible involvement of acetylcholine (ACh) in the regulation of alpha MSH secretion from the pars intermedia of the frog (Rana ridibunda) using the perifusion technique. When intact neurointermediate lobes (NIL) were exposed to graded doses of ACh (3 X 10(-7) to 3 X 10(-4) M), a dose-dependent stimulation of alpha MSH release was observed. Repeated administration of ACh (10(-4) M) induced reproducible responses of NIL without any desensitization phenomenon. ACh was also capable of stimulating alpha MSH release from dispersed intermediate lobe cells, indicating that the neurotransmitter exerts its effect by acting directly on frog melanotrophs. Using the monoclonal antibody M-35 against calf muscarinic receptors we have visualized, by the immunofluorescence technique, the presence of muscarinic receptor-like immunoreactivity in the frog pars intermedia. The stimulatory action of ACh was mimicked by both nicotine and muscarine (10(-5) M each). Nicotine-induced stimulation of alpha MSH release was partially abolished by alpha-bungarotoxin (10(-6) M) and hexamethonium (10(-4) M). The stimulatory effect of muscarine was suppressed by atropine and the M1-muscarinic antagonist pirenzepine (10(-5) M), but not by the M2-muscarinic antagonist gallamine. We have investigated the effect of ACh during administration of specific nicotinic and muscarinic antagonists. While hexomethonium or atropine could block only part of the stimulatory effect of ACh, concomitant administration of these antagonists totally abolished the response of NIL to ACh. Finally, the stimulatory effect of ACh was not impaired during prolonged administration of the beta-adrenergic antagonist propranolol. These data show that ACh stimulates in vitro alpha MSH secretion by frog NIL. Our results also indicate that amphibian pars intermedia cells possess two types of cholinergic receptors, an M1-muscarinic receptor sensitive to pirenzepine and nicotinic receptors sensitive to hexamethonium and alpha-bungarotoxin.

Acetylcholine↗

PubMed1989

Processing of thyrotropin-releasing hormone prohormone (pro-TRH) in the adult rat pancreas: identification and localization of pro-TRH-related peptides in beta-cells of pancreatic islets.

Rat TRH prohormone (pro-TRH) contains five separate copies of the TRH progenitor sequence, Gln-His-Pro-Gly. All five sequences are flanked by paired basic amino acid cleavage sites and linked together by connecting sequences. RIAs to synthetic TRH and prepro-TRH-(178-199) were used to investigate pro-TRH processing in the endocrine pancreas of adult rats. HPLC analysis of adult rat pancreatic extracts showed the presence of a major immunoreactive peptide eluting at the position of prepro-TRH-(178-199). An additional peak coeluting with [less than Glu172]prepro-TRH-(172-199) (less than Glu = pyroglutamyl) revealed the presence of a C-terminally extended form of TRH. Quantification of TRH in pancreatic extracts indicated the presence of 22 mol TRH/mol prepro-TRH-(178-199) and 17 mol TRH/mol [less than Glu172]prepro-TRH-(172-199). Treatment of rats with streptozotocin markedly reduced the pancreatic content of both immunoreactive TRH (-84%) and immunoreactive prepro-TRH-(178-199) (-62%). Light microscopic immunocytochemistry showed that prepro-TRH-(178-199)-like immunoreactivity was exclusively located within insulin-containing cells of the pancreatic islets. At the electron microscopic level, prepro-TRH-(178-199) immunoreactivity appeared to be concentrated in secretory granules. The present study demonstrates that processing of pro-TRH generates both non-TRH- and TRH-related peptides in the adult rat pancreas. Our data also indicate that beta-cells of the endocrine pancreas are the major source of TRH- and pro-TRH-derived peptides.

Amino Acid Sequence↗

PubMed1989

Identification of vasotocin-like immunoreactivity in chromaffin cells of the frog adrenal gland: effect of vasotocin on corticosteroid secretion.

The presence of neurohypophyseal nonapeptides in the adrenal gland of nonmammalian vertebrates and the possible action of these regulatory peptides on corticosteroid secretion have never been investigated. We have applied the indirect immunofluorescence technique to examine whether vasotocin (AVT) and/or mesotocin (MT) are located in frog adrenal (interrenal) tissue. Using antisera against AVT and tyrosine hydroxylase, we found that all chromaffin cells contain an AVT-like peptide. Labeling of consecutive sections with phenylethanolamine-N-methyltransferase or AVT antibodies showed that both noradrenaline- and adrenaline-storing cells contain AVT-like immunoreactivity. In contrast no labeling of frog adrenal slices was observed using a MT antiserum. At the ultrastructural level, the immunogold technique revealed that the AVT-immunoreactive peptide is sequestered in chromaffin granules with varying electron densities. Filtration of frog adrenal tissue extracts on Sep-Pak C-18 cartridges showed that the elution profile of the AVT-like peptide was similar to that of synthetic AVT. The apparent concentration of AVT in the adrenal was 2.7 ng/g tissue. Since chromaffin cells represent approximately one third of all interrenal cells, the actual concentration of AVT in chromaffin tissue was about 8 ng/g tissue. The role of AVT in the regulation of frog adrenal steroidogenesis was studied in vitro using perifused frog interrenal slices. Graded doses of AVT (10(-10)-10(-7) M) induced a dose-dependent stimulation of both corticosterone and aldosterone secretion. The other neurohypophyseal peptides (vasopressin, oxytocin, and MT) were also able to enhance corticosteroid secretion, but AVT was by far the most potent stimulator of steroidogenesis. Prolonged administration (4 h) of AVT induced a rapid increase in corticosterone and aldosterone output, followed by a gradual decline of corticosteroid secretion. These results show that an AVT-like peptide is stored in chromaffin granules of frog adrenal gland. Our data also indicate that synthetic AVT is a potent stimulator of corticosteroid secretion by frog interrenal cells. Since in amphibians adrenocortical and chromaffin cells are intimately intermingled, these results suggest that AVT produced by chromaffin cells may regulate corticosteroid release locally, through a cell to cell mode of communication.

Adrenal Cortex↗

PubMed1989

Dual effects of thyrotrophin-releasing hormone (TRH) on K+ conductance in frog pituitary melanotrophs. TRH-induced alpha-melanocyte-stimulating hormone release is not mediated through voltage-sensitive K+ channels.

Modulation of the activity of K+ channels by TRH and the possible involvement of this modulation in TRH-induced release of alpha-MSH were studied in cultured frog melanotrophs, using patch-clamp and perifusion techniques. Pars intermedia cells were enzymatically dispersed and cultured in Leibovitz medium. In order to test the viability of cultured cells, the amount of alpha-MSH released into the medium was measured by radioimmunoassay every day for 1 week of culture. The total amount of alpha-MSH released during the first 4 days of culture was 8.6 times higher than the intracellular content of alpha-MSH on day 1. Melanotrophs were identified by an indirect immunofluorescence technique using a specific antiserum to alpha-MSH. Recordings obtained in whole-cell, cell-attached and excised patch-clamp configurations showed that TRH induced a transient polarization concomitant with an increase in the probability of opening of Ca2+-activated K+ channels. This transient response was followed by a depolarization accompanied by an enhanced frequency of action potential discharge. TRH also induced a decrease in voltage-dependent K+ conductance. Application of tetraethylammonium, a K+ channel blocker, depolarized the cells and increased the basal secretory level without noticeable changes in TRH-evoked alpha-MSH release. These results demonstrate that the neuropeptide TRH both stimulates Ca2+-sensitive K+ channels and inhibits voltage-dependent K+ current in pituitary melanotrophs. Our data indicate that TRH-induced secretion of alpha-MSH is not a direct consequence of the lowering of K+ conductance. It thus appears that basal and TRH-induced alpha-MSH release occur through distinct pathways; the spontaneous release of alpha-MSH is probably linked to membrane potential, while modulation of the electrical activity is not directly involved in TRH-induced activation of the secretory process.

Animals↗

PubMed1989

Effect of serotonin on alpha-melanocyte-stimulating hormone secretion from perifused frog neurointermediate lobe: evidence for the presence of serotonin-containing cells in the frog pars intermedia.

We have examined the presence of 5-hydroxytryptamine (serotonin; 5-HT) in the intermediate lobe of the frog pituitary and investigated the effect of exogenous 5-HT on alpha-melanocyte-stimulating hormone (alpha-MSH) release from the perifused neurointermediate lobe (NIL). Using a specific antiserum against 5-HT, the indirect immunofluorescence technique revealed the presence of 5-HT-like immunoreactivity (5-HT-LI) in discrete cells, generally gathered in small clusters among parenchymal cells, and in numerous neurites surrounding melanotrophic cells. At the electron microscopic level, using a silver-gold intensification procedure, 5-HT-LI was localized in dense-core secretory vesicles within specific pituitary cells which appear to be different from pituitary melanotrophs. Dense accumulation of gold particles was also observed in nerve fibres running between parenchymal cells. A combination of high-performance liquid chromatography analysis and electrochemical detection showed the presence of both 5-HT and its metabolite 5-hydroxyindol acetic acid (5-HIAA) in frog NIL extracts (534 +/- 40 and 1245 +/- 65 (S.E.M.) pg/mg wet tissue respectively). Administration of graded doses of 5-HT (from 1 to 30 mumol/l) to perifused frog NIL induced a dose-dependent inhibition of alpha-MSH release. Repeated pulses of 5-HT (10 mumol/l each) induced a reproducible inhibition of alpha-MSH without any desensitization phenomena. The inhibitory effect of 5-HT was partially blocked by the serotonergic antagonists methysergide and ICS-205-930 (10 mumol/l each). Concomitant administration of methysergide and ICS-205-930 (10 mumol/l each) totally abolished 5-HT-evoked inhibition of alpha-MSH. Fenfluramine, a releaser of 5-HT, induced a slight but significant reduction of alpha-MSH secretion. While 5-HT caused a marked inhibition of alpha-MSH release from intact NIL, 5-HT was devoid of effect on acutely dispersed pars intermedia cells suggesting that 5-HT does not exert a direct action on pituitary melanotrophs. We have examined the effect of specific dopaminergic, GABAergic and alpha-adrenergic antagonists on 5-HT-induced alpha-MSH inhibition. We observed that sulpiride and SR 95531 (10 mumol/l each) did not affect the response of NIL to 5-HT while yohimbine (10 mumol/l) suppressed the inhibitory action of 5-HT. Taken together, our results indicate that discrete cells of the frog pars intermedia contain the neurotransmitter 5-HT which may act locally to inhibit alpha-MSH release.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1988

Processing of thyrotropin-releasing hormone prohormone (pro-TRH) generates pro-TRH-connecting peptides. Identification and characterization of prepro-TRH-(160-169) and prepro-TRH-(178-199) in the rat nervous system.

Rat thyrotropin-releasing hormone prohormone (pro-TRH) contains five separate copies of the TRH progenitor sequence: Gln-His-Pro-Gly. Each of the five sequences is flanked by pairs of basic residues and linked together by one of several predicted connecting sequences. Two of the pro-TRH-connecting peptides, prepro-TRH-(160-169) and prepro-TRH-(178-199), were detected in extracts of rat neural tissues by radioimmunoassay using antibodies directed against the corresponding synthetic probes. Endogenous prepro-TRH-(160-169) and prepro-TRH-(178-199) were purified by gel exclusion chromatography, reverse-phase high pressure liquid chromatography, and ion-exchange chromatography. Structural identification of each peptide was achieved by chromatographic comparison with synthetic standards, immunological analysis, and tryptic mapping. Equimolar amounts of these connecting fragments were observed in hypothalamus and spinal cord. Quantification of TRH in spinal cord and hypothalamus extracts revealed the presence of 4.9-6.3 mol of TRH/mol of prepro-TRH-(178-199) and 4.4-6 mol of TRH/mol of prepro-TRH-(160-169), respectively. By using the indirect immunofluorescence technique, prepro-TRH-(178-199) immunoreactive cell bodies were found in the paraventricular nucleus of the hypothalamus, and a dense plexus of immunopositive nerve terminals was observed in the external zone of the median eminence, in a distribution similar to that described for TRH. These studies demonstrate that prepro-TRH-(160-169) and prepro-TRH-(178-199) are, together with TRH, predominant storage forms of the TRH precursor in hypothalamus and spinal cord, being present in molar ratios corresponding to those expected for a nearly complete processing of the prohormone molecule. The presence of pro-TRH-connecting peptides in various brain regions, including the median eminence, suggests that these peptides might act as neuromodulators in the central nervous system and/or neuroendocrine signals at the pituitary level. In the olfactory lobes, prepro-TRH is processed differently since a C-terminally extended form of TRH, prepro-TRH-(172-199), is found as a major end product along with lower but significant amounts of prepro-TRH-(178-199) and prepro-TRH-(160-169). The striking difference in pro-TRH processing patterns among the various tissues examined suggests differential regulating mechanisms for TRH and/or TRH-related activities.

Amino Acid Sequence↗

PubMed1988

The amino acid sequences of frog heart atrial natriuretic-like peptide and mammalian ANF are closely related.

Despite few studies conducted in non-mammalian species, there has been a number of reports pertaining to the occurrence of a natriuretic-like substance in lower organisms. Thus, an immunoreactive substance reacting with antibodies directed against mammalian atrial natriuretic factor has previously been detected both in heart atria and ventricles of a chordate, the frog. This substance was isolated and purified from frog heart atria and its amino acid sequence established. The sequence, Ala-Pro-Arg-Ser-Ser-Asp-Cys-Phe-Gly-Ser-Arg-Ile-Asp-Arg-Ile-Gly-Ala-Gln- Ser-Gly - Met-Gly-Cys-Gly-Arg-(Phe), is highly homologous to known mammalian ANF sequences. However, when aligned with the complete mammalian ANF precursor sequence at positions 121 to 151, it exhibits a single amino acid insertion at position 129 and other substitutions at positions 121, 125, 133, 135, 144, 147 and 148. Some evidence is also presented concerning the occurrence of uncleaved frog pronatriodilatin, the precursor form of ANF. This study represents the first report pertaining to the structure of a non-mammalian ANF and its precursor.

Amino Acid Sequence↗

PubMed1988

Distribution and characterization of neuropeptide Y-like immunoreactivity in the brain of the crested newt.

The newt brain represents a simplified model for the increasingly complex vertebrate neuronal organization. The localization of neuropeptide Y-like (NPY-like) containing neurons in the brain of Triturus cristatus was studied by means of indirect immunofluorescence, peroxidase-antiperoxidase, and avidin-biotin techniques using a highly specific antiserum. NPY-like positive cell bodies were observed in several areas, most notably in the telencephalon (primordium hippocampi and amygdaloid complex), the preoptic and suprachiasmatic areas, the hypothalamus, the dorsal thalamus, the tegmentum, and the rhombencephalon (laterolateral grey column and raphe area). Nerve fibres were particularly abundant in the pallium, striatum, septum, amygdaloid, preoptic neuropils, and pars intercalaris diencephali. Bundles of NPY-immunoreactive fibres also were visualized in the dorsal thalamus and in the posterior hypothalamus. The pars intermedia lacked any NPY-like positive fibres. Neuronal processes also were found in the tectum mesencephali and in the body of the cerebellum. A prominent NPY-like fibre network was observed in the octavolateralis. Concentrations of NPY measured by means of a specific radioimmunoassay were threefold higher in the hypothalamus (15.2 +/- 1.3 ng/mg proteins) than in the rhombencephalon (4.9 +/- 0.3) and the mesencephalon (4.3 +/- 0.2). The concentration found in the telencephalon was 2.1 +/- 0.3 ng/mg proteins. Sephadex G-50 gel chromatography of whole brain extracts indicated the presence of high molecular weight forms of NPY-like material in addition to the authentic peptide. Both amphibian and mammalian NPY peptides had an apparent molecular weight of 4,000 daltons, as evidenced by immunoblotting analysis. High-performance liquid chromatography demonstrated, however, that the newt peptide was slightly less hydrophobic than porcine NPY. The present findings indicate that NPY-immunoreactive neurons are widely distributed in the brain of urodeles. Our data indicate that the NPY molecule has been relatively well preserved during evolution.

Animals↗

PubMed1988

Immunohistochemical and biochemical evidence for the presence of serotonin in amphibian adrenal chromaffin cells.

The presence of serotonin (5-HT) in chromaffin cells of the frog adrenal (inter-renal) gland has been demonstrated both by immunocytochemical and biochemical techniques. Using antisera against 5-HT and tyrosine hydroxylase (TH) on consecutive sections, we found by means of the indirect immunofluorescence technique that a majority of chromaffin cells were also immunopositive for 5-HT. When antibodies to 5-HT and phenylethanolamine-N-methyltransferase (PNMT) were applied on consecutive sections, 5-HT-like immunoreactivity was observed in almost all epinephrine-producing cells which represented about 90% of the total chromaffin cells. No 5-HT-containing fibres could be detected. At the ultrastructural level, using a pre-embedding procedure associated with gold-silver intensification of the immunoperoxidase reaction, 5-HT-immunoreactivity was visualized in secretory vesicles essentially located in the periphery of epinephrine cells. Combination of high performance liquid chromatography and electrochemical detection showed the presence of both 5-HT and its metabolite 5-hydroxyindolacetic acid (5-HIAA) in frog adrenal extracts. Transection of the splanchnic nerve enhanced 5-HT immunoreactivity and augmented the amount of 5-HT in adrenal extracts. Taken together, these results indicate that epinephrine-producing cells of the frog adrenal contain significant amounts of serotonin. The observation of the storage of 5-HT in secretory vesicles of epinephrine cells suggests that serotonin may be released with catecholamines under stress conditions.

Adrenal Medulla↗

PubMed1988

Immunohistochemical localization of gonadotropin-releasing-hormone-associated peptide in the brain of the frog.

Gonadotropin-releasing-hormone (GnRH)-associated peptide (GnRH-AP) is a 56 amino acid neuropeptide derived from the GnRH prohormone. GnRH-AP corresponds to the C-terminal fragment flanking the GnRH peptide. Using an antiserum raised against human GnRH-AP [1-56], or against human GnRH, we have investigated the neuronal systems containing either peptide in the central nervous system of the frog Rana ridibunda by immunohistological techniques. A main group of GnRH-AP-containing perikarya was found in a dorsoventral orientation of the supra anterior preoptic area (SAPA) just in front of the preoptic recess. Fibers originating from these perikarya projected rostrally toward the medial septal nucleus and the diagonal band of Broca. A network of GnRH-AP-immunoreactive (ir) fibers runs caudally from the SAPA toward the ventral hypothalamus. A high density of GnRH-AP-ir terminals was found in the median eminence. A few positive fibers were detected in the neural lobe of the pituitary, particularly in the region bordering the pars intermedia. Labelling of consecutive sections by either GnRH-AP or GnRH antibodies showed that GnRH and GnRH-AP-like irs were contained in the same cells of the SAPA. The double-staining technique with electrophoretic elution confirmed the colocalization of GnRH and GnRH-AP within the same neurons. Such a coexistence indicates that frog GnRH originates from a high molecular weight precursor which is closely related to rat pro-GnRH. The relative preservation of the C-terminal sequence of the pro-GnRH during evolution suggests that GnRH-AP may possess intrinsic biological activity. The high density of GnRH-AP-containing neurons projecting through the external zone of the median eminence would support the concept that GnRH-AP is involved in the modulation of pituitary hormone secretion.

Animals↗

PubMed1988

Neuronal and paracrine regulation of adrenal steroidogenesis: interactions between acetylcholine, serotonin and vasoactive intestinal peptide (VIP) on corticosteroid production by frog interrenal tissue.

The adrenocortical cells of frog interrenal (adrenal) tissue are controlled by multiple factors. Recently, we have shown that corticosteroidogenesis is stimulated by acetylcholine released from splanchnic nerve terminals as well as by serotonin and vasoactive intestinal peptide (VIP) which are both contained in chromaffin cells. Since these 3 putative neuroregulators are known to interact with each other on various target organs, we have investigated possible coordinate actions of acetylcholine, serotonin and VIP on adrenal steroid production, using a perifusion system technique for frog interrenal tissue. Simultaneous infusion of submaximal doses of VIP (10(-5) M) and acetylcholine (5 X 10(-5) M) induced stimulations of corticosteroids (corticosterone and aldosterone) which were strictly additive. When VIP (10(-5) M) and serotonin (5 X 10(-6) M) were infused together, a potentiation of the individual responses was observed. In contrast, concomitant infusion of acetylcholine (5 X 10(-5) M) and serotonin (5 X 10(-6) M) caused a total blockage of the stimulatory effect of serotonin. Muscarine (10(-5) M) caused a similar blockade of the response of adrenocortical cells to serotonin while nicotine (5 X 10(-5) M) did not alter the stimulatory effect of serotonin. The inhibitory effect of acetylcholine on serotonin-induced steroidogenesis was antagonized by atropine (10(-5) M). Thus, acetylcholine appears to block the corticotropic action of serotonin by interacting with typical muscarinic receptors. Taken together our results indicate that 3 of the neuroregulators which participate in the control of adrenal steroidogenesis, namely acetylcholine, serotonin and VIP, may interact on their target cell to modulate the activity of their congeners.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMed1988

Coexistence of melanin-concentrating hormone and alpha-melanocyte-stimulating hormone immunoreactivities in the central nervous system of the locust, Locusta migratoria.

The distribution of melanin concentrating hormone (MCH) in the central nervous system of the locust Locusta migratoria was studied by the indirect immunofluorescence technique, using antibodies against salmon MCH. Most MCH-immunoreactive perikarya were found in the optic lobes at both sides of the brain, dorsally with respect to the lamina ganglionaris. The same neurons also contain alpha-melanocyte-stimulating hormone (alpha-MSH)-like material. In addition, a moderate number of MCH-like neurons, which were devoid of alpha-MSH-immunoreactive substances, was observed in the pars intercerebralis. Bright immunofluorescent fibers were visualized in various regions of the central nervous system of the locust: the optic lobes, the ocelli, the proto-and deuterocerebrum, the subesophageal connectives and the corpora cardiaca. In the ventral nerve cord and the subesophageal ganglion, where alpha-MSH-like cell bodies were encountered, MCH immunoreactive perikarya were absent and immunoreactive fibers were scarce. The coexistence of MCH and alpha-MSH-immunoreactive material within the same specific neurons might indicate an evolutionary relationship of both peptides.

Animals↗

PubMed1988

Distribution and characterization of neuropeptide Y in the brain of an elasmobranch fish.

Using a specific antiserum raised against synthetic neuropeptide Y (NPY), the distribution of immunoreactivity in the brain and pituitary of the elasmobranch fish Scyliorhinus canicula has been examined with the indirect fluorescence and the peroxidase-antiperoxidase methods. The highest density of NPY-immunoreactive neurons was found in the basal telencephalon and in the hypothalamus. Numerous NPY-containing perikarya were located in the entopeduncular and the preoptic nuclei, in the nucleus lobi lateralis and in the nucleus lateralis tuberis. NPY-immunopositive fibers were observed throughout the fish brain. In particular, dense networks of fibers were present in the entopeduncular and the habenular nuclei, in the nucleus tuberculi posterioris and in the lateral lobes. Scattered fibers were observed in all other parts of the brain except in the cerebellum where no NPY-immunoreactive material could be detected. A plexus of NPY-immunoreactive fibers arising from the preoptic neurosecretory complex appeared to run through the basal hypothalamus and the pituitary stalk. These fibers terminated in the intermediate lobe of the pituitary, suggesting that NPY may be involved in the control of melanotropin secretion. The NPY-immunoreactive material localized in the brain and pituitary was characterized by combining high-performance liquid chromatography (HPLC) analysis and radioimmunological detection. Brain and pituitary extracts showed a good cross-reactivity to the NPY antiserum, but serial dilutions of tissue samples did not completely parallel the standard curve. HPLC analysis resolved two major forms of immunoreactive NPY in the hypothalamus while the pars intermedia contained only authentic NPY. The widespread distribution of NPY neurons in the fish brain and pituitary suggests the involvement of NPY in a variety of physiological functions, including the neuroendocrine control of the pituitary.

Animals↗

PubMed1988

Transient expression of somatostatin receptors in the rat cerebellum during development.

Somatostatin and somatostatin receptors have not been identified in adult rat cerebellum. In contrast, during the development, somatostatin-containing neurons have been visualized in the deep layers of the cerebellum. The present study shows that during ontogenesis, somatostatin receptors are present in close association with the external granule cell layer of the cerebellum. No correlation was found between the location of immunoreactive somatostatin and the distribution of somatostatin receptors. The disappearance of somatostatin receptors, from postnatal day 13 to 23, was concomitant with the involution of the external germinal layer.

Age Factors↗

PubMed1988

Immunocytochemical distribution of neurons containing a peptide derived from thyrotropin-releasing hormone precursor in the rat brain.

Using an antiserum to a 22-amino acid synthetic peptide corresponding to sequence 178-199 of the precursor of thyrotropin-releasing hormone (pro-TRH), we have studied by immunocytochemistry the distribution of immunoreactive pro-TRH in the rat brain. Immunostaining found in several regions of the brain had a distribution similar to that previously reported for TRH. Reaction product was found in both neuronal cell bodies and processes. These results indicate that peptide(s) derived from pro-TRH are transported along the axons with TRH itself. Moreover, the presence of immunoreactive nerve endings in different areas including the median eminence suggests that this material might have a neuromodulator/neurotransmitter role in the central nervous system and could also be released into the pituitary portal plexus.

Animals↗

PubMed1988

Displaceable somatostatin binding sites in the gray matter and pyramidal paths of the human developing spinal cord.

The binding of the somatostatin analogue, 125I-iodo-Tyr-[Tyr0,D-Trp8]S14, to the foetal (18- and 24-week-old) and infant (newborn and 17-month-old) spinal cord was examined using in vitro autoradiography. Somatostatin binding sites were detected at cervical, thoracic and lumbosacral levels in foetal as well as in infant spinal cord. The radiolabelling was localized over the grey especially in the superficial layers of the dorsal horn including the substantia gelatinosa and the marginal zone. In foetal and newborn spinal cord, the direct and crossed pyramidal paths exhibited a substantial binding of the ligand. A similar labelling was not observed in the pyramidal paths of a 17-month-old child or in anencephalic newborn spinal cord or previously described in adult. These results emphasize the early presence of somatostatin binding sites during the ontogeny of the human spinal cord. Further, the transient appearance of somatostatin binding sites in the pyramidal paths, prior the myelination, raises the question whether somatostatin receptors could be involved in the maturation of certain normal paths.

Aging↗