Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Light microscopic double immunocytochemical stainings, performed on sea bass hypothalamo-hypophysial sections, revealed the projection of different neuropeptide-immunoreactive neurons innervating the hormone-producing cell populations in the pituitary gland. In the rostral pars distalis (PD) the ACTH cells were found in close proximity to fibers immunoreactive for somatostatin (SRIF), growth hormone-releasing hormone (GRF), corticotropin-releasing hormone (CRF), vasotocin (VT), isotocin (IT), substance P (SP), neurotensin, and galanin (GAL), while the PRL cell zone seemed only innervated by nerve fibers immunopositive for GAL. In the proximal PD, fibers immunoreactive for SRIF, GRF, VT, IT, cholecystokinin, SP, neuropeptide Y, and GAL formed a close relationship with the growth hormone cells. The gonadotrophs were observed near nerve fibers immunostained for gonadotropin-releasing hormone, IT, and less obviously GRF and VT, while fibers positive for GRF, CRF, VT, IT, SP, and GAL penetrated between and formed a close association with the thyrotrophs. In the pars intermedia the MSH cells and the PAS-positive (PAS+) cells seemed both innervated by separate nerve fibers immunoreactive for GRF, CRF, melanin concentrating hormone, VT, IT, and SP. All these results suggest a functional role of the neuropeptides in the adenohypophysis of the sea bass, possibly in the synthesis and/or release of hypophysial hormones from the different cell types.
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PMID:Immunocytochemical demonstration of close relationships between neuropeptidergic nerve fibers and hormone-producing cell types in the adenohypophysis of the sea bass (Dicentrarchus labrax). 246 54

Eight patients with active acromegaly due to GH-producing pituitary adenoma were studied. GH secretory dynamics in vitro was evaluated by adding GRF, CRF, or a somatostatin analog, SMS 201-995 to the perifusate of dispersed cells from tumors. A comparison was made between the data obtained in preoperative tests for GH secretion and those obtained in experiments in vitro. Before operation, the GRF test (100 micrograms, iv) resulted in no GH response in three of six patients examined. The CRF test (100 micrograms, iv) resulted in a paradoxical GH increase in two of the same six patients. In vitro studies performed on adenoma cells revealed that exposure to GRF (100 ng/ml) elicited an increase in GH in seven of eight patients examined. Exposure to CRF (100 ng/ml) caused an enhanced GH secretion in four of the same eight patients. There were cases in which GH response to these hypothalamic hormones was observed in vitro but not in vivo, whereas there was only one case in which CRF caused an increase in GH in vivo but not in vitro. Thus, GH secretory dynamics was not always the same in vivo and in vitro. The discrepancy could be ascribed to the different secretory status of hypothalamic hormone (e.g., GRF or somatostatin) in vivo in each acromegalic patient.
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PMID:Comparative in vivo and in vitro studies on abnormal GH secretion in patients with acromegaly. 249 48

The dog pituitary pars intermedia (PI) appears to consist of relative large numbers of ACTH-containing cells in addition to the more abundant alpha MSH-containing cells. Since regulation of PI secretion probably varies across mammalian species, this study was undertaken to identify substances potentially involved in the control of dog PI POMC peptide secretion and to determine if these substances altered the secretion of immunoreactive (IR) ACTH and IR-alpha MSH in a parallel fashion. Pituitary neurointermediate lobes from dogs were collected and dispersed, and the PI cells obtained were perifused. For comparison, rat PI and pars distalis (PD) cells as well as dog PD cells were similarly collected and perifused. Dog PI cells secreted IR-alpha MSH at a basal rate of 125 +/- 59 (mean +/- SD) pg/min.10(5) cells and IR-ACTH at a rate of 40 +/- 9 pg/min.10(5) cells (molar IR-alpha MSH/IR-ACTH = 10). In contrast, secretion rates for IR-alpha MSH and IR-ACTH from perifused rat PI cells were 171 +/- 108 and 3 +/- 2 pg/min.10(5) cells, respectively (molar IR-alpha MSH/IR-ACTH = 179). Using Sephadex G-50 gel filtration chromatography, virtually all of the IR-beta-endorphin secreted by dog PI cells eluted near beta-endorphin (1-31). In addition, all of the IR-alpha MSH secreted by dog PI cells coeluted with synthetic alpha MSH on the G-50 column, but IR-ACTH appeared in two peaks, one eluting near porcine ACTH-(1-39) and another, apparently larger mol wt species. Dopamine and somatostatin were found to inhibit the secretion of IR-alpha MSH and IR-ACTH from perifused dog PI cells in a parallel and dose-dependent fashion. Norepinephrine and epinephrine similarly inhibited POMC peptide secretion, but this effect was blocked by haloperidol, suggesting that it was mediated through a dopamine receptor. CRF stimulated the secretion of both hormones from dog PI, and this effect was abolished by treatment of the cells with either dopamine or somatostatin. Cortisol had no effect on either basal or CRF-stimulated secretion of IR-alpha MSH or IR-ACTH from dog PI cells, but it did inhibit CRF-stimulated IR-ACTH from perifused dog PD. These results suggest that 1) dog PI secretes considerably more IR-ACTH than that in the rat; 2) the probable separate cell sources of IR-alpha MSH and IR-ACTH in dog PI are regulated in an identical fashion; and 3) dopamine, somatostatin, and CRF may function in the physiological or pathophysiological regulation of dog PI.
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PMID:Regulation and secretion of proopiomelanocortin peptides from isolated perifused dog pituitary pars intermedia cells. 253 71

The present review is dealing with the five major hypothalamic hypophysiotropic neuropeptides (H.H.N.P.) purified and synthesized so far. Four of them specifically stimulate the secretion of one or several anterior pituitary (A.P.) hormones, i.e. thyroliberin (TRH) on TSH and prolactin, gonadoliberin (GnRH) on LH and FSH, corticoliberin (CRF) on ACTH and precursor peptides and somatocrinine (GRF) on GH. The fifth one, somatostatin (SRIF), inhibits the secretion of all A.P. hormones, excepted LH and FSH. All H.H.N.P. affect, positively or negatively, in a dose- and time-dependent manner, the release of stored hormones and their neosynthesis. These responses are submitted to multihormonal modulations. They are initiated by the occupancy of high affinity specific binding sites which have been extensively characterized and morphologically localized. Informations concerning molecular characterization and cloning of receptors for any H.H.N.P. are still awaited. By contrast, the transduction mechanisms which are activated by the occupation of receptors have been extensively studied. They vary depending on H.H.N.P.: TRH and GnRH activate the catabolism of polyphosphoinositides and ensuing pathways, CRF and GRF activate and SRIF inhibits adenylate cyclase dependent pathways. In addition, Ca2+, from extracellular and intracellular sources, play a pivotal role in all cases. The intracellular mechanisms responsible for the last steps of H.H.N.P. action, i.e. exocytosis of secretory granules and transcription of target genes, are however still unknown.
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PMID:[Hypothalamic hypophysiotropic neuropeptide receptors]. 255 5

We have previously reported that the hypothalamo-pituitary-adrenal response to insulin-induced hypoglycaemia is normal while the cortisol release to pituitary stimulation by corticotrophin releasing factor (CRF-41) is reduced in obesity. Impaired growth hormone (GH) secretion is also found in obesity which may result from altered central levels of somatostatin (SMS). We have investigated, by giving a simultaneous infusion of SMS to six volunteer normal weight men during a CRF test, whether it is possible for SMS to modify pituitary-adrenal function. Each subject received intravenous CRF-41 (0.5 micrograms/kg) on two occasions during an infusion of isotonic saline or SMS (4 micrograms/min) in a randomized double-blind study. Plasma GH, cortisol, ACTH and SMS were measured. Three subjects demonstrated GH peaks during saline infusion but no peaks were seen in any subject during SMS infusion. No significant difference was found between peak cortisol responses during saline or SMS infusion (SMS cortisol 443 +/- 61 nmol/l, saline cortisol 485 +/- 52 nmol/l); neither was there any difference in the ACTH responses. We conclude that SMS does not alter the pituitary response to CRF in normal weight men and is thus less likely to be responsible for the altered pituitary-adrenal function seen in obesity. Further studies of alternative mechanisms are required to explain the cause of this abnormality.
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PMID:The pituitary-adrenal response to CRF-41 is unaltered by intravenous somatostatin in normal subjects. 257 84

Atrial natriuretic factor (ANF) binding sites in adult rat exocrine pancreas were studied by autoradiography using slide-mounted frozen tissue sections with mono-iodinated ANF (101-126) as the tracer. Radiolabel was displaced by unlabeled atrial peptide (IC50 = 2 X 10(-11) M). High specific labeling was found in pancreatic acini. The presence of endogenous ANF has also been demonstrated in the exocrine pancreas by immunocytochemistry on ultra-thin sections obtained by cryoultramicrotomy. ANF-like immunoreactivity was found in acinar and centro-acinar cells as well as cells of the intercalated duct. For these cells, immunostaining was observed at the plasma membrane level, in the cytoplasm and nucleus. In the cytoplasm, ANF-like immunoreactivity was observed in the cytoplasmic matrix, mitochondria, and zymogen granules. In the nucleus, ANF-like immunoreactivity was distributed in the vicinity of the heterochromatin region primarily in the euchromatin. It was also detected in the plasma membrane of microvilli of acinar and duct cells, and in the lumen of secretory ducts. In centro-acinar cells, the reaction product was also found sparsely at the nuclear envelope. No immunoreactivity was observed when anti-human ANF serum preincubated with rat ANF was used. No modifications were observed when this antiserum was preincubated with heterologous peptides (NPY, CRF, GRF, TRH, somatostatin). These data provide autoradiographic evidence of ANF binding sites, indicate the presence of this peptide in acinar and centro-acinar cells as well as cells of the intercalated duct, and immunocytochemical evidence for the internalization of endogenous ANF by exocrine pancreas.
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PMID:Atrial natriuretic factor and exocrine pancreas: autoradiographic localization of binding sites and ultrastructural evidence for internalization of endogenous ANF. 281 60

Regulation of adenohypophyseal hormone secretions has been shown to involve cyclic AMP production, modulation of phosphatidyl inositol diphosphate breakdown and Ca2+ mobilization. Various neurohormone receptors are positively or negatively coupled to adenylate cyclase activity in anterior pituitary cells. The effects of these neurohormones on adenylate cyclase activity are consistent with the effect on hormone secretions, suggesting that modulation of the enzyme activity is actually involved in the regulation of adenohypophyseal secretions. Thus DA inhibits, whereas VIP stimulates adenylate cyclase activity of the same cell type, which, according to the effect of these neurohormones on prolactin secretion, appear to be lactotrophs. On the other hand, SRIF inhibits, whereas GRF stimulates the adenylate cyclase activity of another cell type, namely somatotrophs, whereas CRF appears to act on a third cell type, corticotrophs. Peripheral hormones have been shown to modulate the sensitivity of anterior pituitary cells to these neurohormones. Estradiol long-term treatment has an anti-dopaminergic effect on prolactin secretion. The steroid also suppresses the dopamine inhibition of adenylate cyclase. This effect appears selective to the DA inhibition, since AII inhibition of the enzyme is only partially reduced, whereas the somatostatin inhibition is markedly increased. Peripheral hormones seem to affect the sensitivity of adenohypophyseal cells not only by modulating the number of receptors for a given neurohormone but also by interfering with the coupling mechanisms of these receptors. AII and DA inhibit the adenylate cyclase activity of lactotroph cells. The prolactin stimulation induced by angiotensin is not consistent with the effect of the peptide on adenylate cyclase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Multiple coupling of neurohormone receptors with cyclic AMP and inositol phosphate production in anterior pituitary cells. 282 May 13

Radioimmunoassays of brain extracts have shown that several peptides occur in high concentrations in the CNS. The releasing-factor peptides TRF, LRF, somatostatin, CRF and GRF have the highest concentration in the hypothalamic extracts. High levels of somatostatin, CCK octapeptide, neuropeptide Y (NPY) and vasoactive intestinal peptide (VIP) are found in cortical extracts. Substance P, CCK, NPY, and enkephalins are present in high concentrations in basal ganglia and mesolimbic areas. Pharmacological doses of these peptides result in several behavioural and vegetative effects. Immunocytochemical studies show that the CNS peptides are localised in neurones and in synaptic vesicles. In vitro studies with brain tissues show that peptides are capable of modifying the ongoing classical neurotransmission. In depressive patients several neuropeptides (CCK, CRF and NPY) have been shown to have low CSF levels. Patients dying of senile dementia have low cortical levels of somatostatin, CRF and substance P. In schizophrenic patients CCK peptides have shown to improve some symptoms. At present the therapeutic potentials of peptides are poorly known. More studies are required to understand their role in neurotransmission and related pathological states.
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PMID:Peptides and neurotransmission in the central nervous system. 282 29

The radiolabelled somatostatin analogs [125I-Tyr0,DTrp8]S14 and [Leu8,DTrp22,125I-Tyr25]S28 were used as radioligands to study the distribution of somatostatin receptors in the rat hypothalamus. Previous studies have detected very few somatostatin-binding sites in the hypothalamus using in vitro autoradiography. Since the lack of autoradiographic labelling has been ascribed to the occupancy of the receptors by endogenous ligands, we have developed a method using guanosine triphosphate (GTP) pretreatment to unmask somatostatin receptors. Preincubation of brain slices with 10(-6) M GTP, by desaturating the occupied receptors, made it possible to reveal the wide distribution of somatostatin-binding sites in the rat hypothalamus. Somatostatin-14 binding site populations were observed in numerous hypothalamic areas including the preoptic area where the receptors likely account for self-inhibition of somatostatin release, the supraoptic nucleus, the bed nucleus of the stria terminalis, the anterior hypothalamic nucleus, the perifornical area, the zona incerta and a mediolateral area located laterally to the ventromedian and dorsomedian nuclei and limited laterally by the mammillo-thalamic tract, the fornix and the optic tract. All structures showing S14-binding sites were labelled by the S28 radioligand. In addition, the paraventricular parvocellular nucleus contained exclusively S28-binding sites, which could be involved in the inhibitory effect of S28 on CRF-mediated endocrine and sympathetic responses. A moderate density of S28-preferring sites was also detected in the periventricular nucleus. In summary, GTP preincubation of brain slices appeared to be a useful technique to reveal multiple somatostatin receptors populations in the brain. The widespread distribution of somatostatin receptors in the hypothalamus is in total agreement with the variety of physiological effects of the somatostatin peptide family.
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PMID:Autoradiographic study of somatostatin receptors in the rat hypothalamus: validation of a GTP-induced desaturation procedure. 284 May 99

A large number of antisera to regulatory vertebrate peptides was tested immunocytochemically on the nervous system of the Colorado potato beetle to further characterize the peptidergic cells of the neuro-endocrine system and to reveal cells participating in endocrine control mechanisms. Neurons, neurosecretory cells, axons and axon terminals were revealed by antisera to ACTH, gastrin, CCK, alpha-endorphin, beta-endorphin, gamma 1-MSH, insulin, motilin, human calcitonin, growth hormone, somatostatin, CRF, ovine prolactin and rat prolactin. Together with previously described results these findings demonstrate that at least 19 different peptidergic cell types are present in the Colorado potato beetle. Several of these cell types are identical with the known neurosecretory cells, while others have not been identified before. The functions of the immunoreactive neurons are as yet unclear, although in two cases the localization of these cells gives some clues. Thus the lateral neurosecretory cells, which are immunoreactive with antisera to beta-endorphin and ovine prolactin, may regulate corpus allatum activity, whereas a CRF immunoreactive substance seems to be used as neurotransmitter by antennal receptors. These immunocytochemical findings do not imply that the immunoreactive substances are evolutionarily related to the vertebrate peptides to which the antisera were raised. It is postulated that if the part of the substance recognized by a certain antiserum is functionally important for the insect, which should be so if the insect peptide is evolutionarily related to its vertebrate homologue, the antiserum should reveal homologous cells in different insect species. The consequence of this hypothesis is, that if an antiserum does not reveal homologous neurons in different insect species, the immunologically demonstrated substance is probably of little physiological importance, and will not be related evolutionarily to the vertebrate analogue. The positive immunocytochemical results in the Colorado potato beetle are discussed in relation to these considerations.
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PMID:Immunocytochemical localization of peptidergic neurons and neurosecretory cells in the neuro-endocrine system of the Colorado potato beetle with antisera to vertebrate regulatory peptides. 285 60


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