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

The regulation of gastrin gene transcription was studied in GH4 pituitary cells transfected with constructs comprised of the first exon of the human gastrin gene and various lengths of 5' regulatory sequences ligated upstream of the reporter gene chloramphenicol acetyltransferase. Gastrin reporter gene activity in GH4 cells was equal to the activity of a reporter gene transcribed from the endogenously expressed growth hormone promoter. The effect of a variety of peptides on gastrin gene transcription including epidermal growth factor (normally present in the gastric lumen), gastrin-releasing peptide, vasoactive intestinal peptide, and somatostatin (present in gastric nerves) was assessed. Epidermal growth factor increased the rate of gastrin transcription almost 3-fold, whereas thyrotropin-releasing hormone and vasoactive intestinal peptide increased gastrin transcription 2- and 1.5-fold, respectively. Gastrin-releasing peptide, a peptide that strongly stimulates gastrin release, weakly increased gastrin transcription (1.3-fold). Somatostatin inhibited the increase in gastrin transcription induced by epidermal growth factor, thyrotropin-releasing hormone, and vasoactive intestinal peptide. Constructs containing various lengths of 5' regulatory sequences defined a response element -40 to -82 base pairs (bp) 5' to the transcription initiation site. This 40-bp sequence contains Sp1 and AP2 binding sites, which suggests that epidermal growth factor and thyrotropin-releasing hormone stimulate gastrin gene transcription through transcription factors that bind to Sp1 and/or AP2 motifs.
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PMID:Regulation of the gastrin promoter by epidermal growth factor and neuropeptides. 256 64

The concentration of 5 neuropeptides, neurotensin (NT), somatostatin (SRIF), corticotropin-releasing factor (CRF), bombesin and thyrotropin-releasing hormone (TRH) was measured in 3 cerebrocortical areas and several subcortical regions in post-mortem brains obtained from patients with histologically verified Alzheimer's disease and from controls without neurological or psychiatric disorders using sensitive and specific radioimmunoassay procedures. In Alzheimer's disease, reductions in the concentration of SRIF and CRF were observed in frontal and temporal cortex. In addition, in Alzheimer's disease, SRIF was also reduced in concentration in the hypothalamus, whereas CRF concentrations were reduced in the caudate nucleus. Neurotensin was reduced in concentration in the amygdala in Alzheimer's disease. No alterations in TRH or bombesin/gastrin-releasing peptide were found. These findings provide further evidence for the pathological involvement of certain neuropeptide-containing neurons in Alzheimer's disease.
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PMID:Neuropeptides in Alzheimer's disease: a postmortem study. 256 90

The concept of multifactorial pituitary control is now well established. As in other cell systems, integration of complex messages involves dynamic interactions of receptors and coupling mechanisms. Regulation of adenohypophyseal secretions has been shown to involve cyclic AMP production, the modulation of phosphatidylinositol phosphate breakdown and Ca2+ mobilization. Dopamine, somatostatin and angiotensin II receptors are negatively coupled to adenylate cyclase in anterior pituitary cells. In the case of angiotensin, this effect on adenylate cyclase appears paradoxical since the peptide markedly stimulates prolactin secretion. In fact, angiotensin II also markedly stimulates inositol phosphate production and this effect could account for the stimulated hormone secretion. In addition, dopamine could inhibit inositol phosphate production stimulated by angiotensin II and thyrotropin-releasing hormone. Dopamine and somatostatin also directly modulate voltage-dependent calcium channels, perhaps through a direct coupling with potassium channels. On the other hand, steroids modulate the sensitivity of adenohypophyseal cells to neurohormones by different mechanisms. In the case of somatostatin, it increases the number of specific binding sites, while in the case of dopamine estradiol affects the transduction mechanisms of D2 dopamine receptors. In conclusion, dopamine and somatostatin receptors appear coupled to various transduction mechanisms through pertussis-sensitive G proteins in anterior pituitary cells.
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PMID:Multiple transduction mechanisms of dopamine, somatostatin and angiotensin II receptors in anterior pituitary cells. 256 74

The present communication examines the influence of somatostatin (SRIF14) on basal and thyrotropin-releasing hormone (TRH)- or growth hormone-releasing factor (GRF)-induced GH secretion in young (6 week old) and adult male chickens. Studies were performed in sodium pentobarbitone-anesthetized chickens where basal plasma concentrations of GH are low and both TRH and GRF consistently stimulate GH release. In both young and adult chickens, basal GH secretion was reduced by SRIF14 infusion (3 micrograms/kg/min). Similarly, in adult and young birds, the GH secretory response to a challenge with a GRF bolus (10 micrograms/kg) was inhibited by the concomitant intravenous infusion of SRIF14 (0.3 or 3.0 micrograms/kg/min). In adult chickens, the GH response to TRH (10 micrograms/kg) was suppressed (by 93%) by SRIF14 infusion (3 micrograms/kg/min) and tended to be inhibited (by 29%) by a lower dose of SRIF14 (0.3 micrograms/kg/min). In contrast, in young chicks, GH release following TRH challenge (either 1 or 10 micrograms/kg) was only partially inhibited by SRIF14 infusion (3 micrograms/kg/min). The response to a TRH challenge (10 micrograms/kg) was unaffected by the low dosage of SRIF14 infusion (0.3 micrograms/kg/min). It is concluded that SRIF14 inhibits both GRF- and TRH-stimulated GH release in young and adult chickens.
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PMID:Somatostatin inhibition of thyrotropin-releasing hormone- and growth hormone-releasing factor-induced growth hormone secretion in young and adult anesthetized chickens. 257 6

The coexistence of varying combinations of substance P (SP), somatostatin (SOM), thyrotropin-releasing hormone (TRH) and met-enkephalin-Arg-Gly-Leu (ENK) with 5-hydroxytryptamine (5-HT) as semiquantitatively revealed by immunocytochemistry in neuronal perikarya of the raphe pallidus et obscurus in the guinea-pig was analyzed. SOM coexisted most frequently with 5-HT, followed by SP, ENK and TRH. Many 5-HT neurons were immunoreactive to 2 or more peptides such as SP/SOM, SOM/ENK, SP/ENK, SOM/TRH, SP/TRH or SOM/SP/ENK. Most of these neurons were shown to project to the spinal cord by retrograde HRP labeling combined with immunocytochemistry. After hemisection of the cervical spinal cord at the C5 level, ENK and 5-HT immunoreactive nerve terminals in the ipsilateral intermediolateral nucleus of the thoracic spinal cord were decreased in number. The results indicate that neurons in the raphe pallidus et obscurus projecting to the spinal cord can be classified into subpopulations according to which peptides coexist with 5-HT, and may have different functions.
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PMID:Coexistence of varying combinations of neuropeptides with 5-hydroxytryptamine in neurons of the raphe pallidus et obscurus projecting to the spinal cord. 257 20

Conditioned medium from thymic reticular monolayers displayed time-dependent accumulations of a concentration-responsive pituitary hormone-releasing activity that has been named thymic neuroendocrine-releasing factor (TNRF). Dopamine blocked and somatostatin (SRIF) attenuated TNRF-induced prolactin (PRL) release. Conversely, SRIF had no effect on TNRF-induced growth hormone (GH) release. TNRF potentiated thyrotropin-releasing hormone (TRH)-stimulated PRL release and was additive to the effects of GH-releasing hormone (GHRH) on GH release. Anterior pituitary cells perifused with TNRF responded with immediate, sustained and reversible increases in hormone release. Partial purification revealed this activity to be greater than 10,000 in molecular weight. These data suggest that the thymus may affect pituitary function.
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PMID:Thymic stromal elements contain an anterior pituitary hormone-stimulating activity. 257 17

The central nervous system effects of neuropeptides on gastric acid and duodenal bicarbonate secretions were examined. In freely moving rats, i.c.v. administration of thyrotropin-releasing hormone (TRH), human gastrin-17 (hG-17) and the somatostatin analogue, desAA 1,2,4,5,12,13 [D-Trp8]somatostatin (ODT8-SS), significantly increased gastric acid secretion, while vasoactive intestinal peptide (VIP) had no effect. In the order of potency and efficacy, the following peptides decreased acid secretion: bombesin (BOM) greater than calcitonin gene-related peptide (CGRP) greater than calcitonin (CT) greater than corticotropin-releasing factor (CRF) greater than beta-endorphin (beta-END) greater than neurotensin (NT). In anesthetized rats, none of these peptides significantly altered proximal duodenal bicarbonate secretion. In awake, freely moving rats, cerebroventricular administration of CGRP significantly decreased while ODT8-SS, TRH and CRF significantly increased duodenal bicarbonate secretion. beta-Endorphin, VIP, CT, BOM, NT and hG-17 given i.c.v. did not significantly alter the bicarbonate response. These results indicate that neuropeptides administered into the central nervous system modulate gastric acid as well as duodenal bicarbonate secretions in awake, freely moving rats in a differentiated fashion. CGRP inhibits both acid and bicarbonate secretions, a somatostatin analogue and TRH both stimulate acid and bicarbonate secretions and CRF inhibits gastric acid but stimulates duodenal bicarbonate secretions.
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PMID:Effects of neuropeptides on gastric acid and duodenal bicarbonate secretions in freely moving rats. 271 Sep 63

Six normal and 8 neoplastic adrenal medullae were assayed for several immunoreactive (IR) proopiomelanocortin (POMC) and hypothalamic peptides. IR-POMC peptides were found in normal and tumor tissue in concentrations ranging from 0.0003 to 0.1% of those in pituitary. Their molecular sizes resembled those of pituitary intermediate lobe POMC peptides. No intact POMC was found. One pheochromocytoma contained fully bioactive IR-adrenocorticotropic hormone (IR-ACTH; Mr approximately 4,500) and an intermediate-sized (Mr approximately 10,000) IR-ACTH with approximately 69% bioactivity. Normal and tumorous medullae contained IR-corticotropin-releasing hormone (CRH) in concentrations ranging from 0.6 to 4% of those in hypothalamus except for one pheochromocytoma that contained 40 times that amount of IR-CRH, which was chromatographically indistinguishable from hypothalamic CRH and fully bioactive. IR-somatostatin and IR-growth hormone-releasing hormone were found in both tissue types, but IR-gonadotropin-releasing hormone and IR-thyrotropin-releasing hormone (TRH) were not, although IR-histidyl-proline diketopiperazine, a putative TRH metabolite, was found. IR-arginine vasopressin was found in two normal medullae, but not in pheochromocytomas.
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PMID:Pituitary and hypothalamic hormones in normal and neoplastic adrenal medullae: biologically active corticotropin-releasing hormone and corticotropin. 282 21

The interaction between somatostatin (SRIF) and thyrotropin-releasing hormone (TRH) on growth hormone (GH) release has been studied on dispersed somatotrophic tumor cells obtained from 7 acromegalic patients. TRH increased GH secretion in 4 cases and SRIF decreased GH secretion in 5 cases. When TRH and SRIF were concomitantly perifused, SRIF, when active by itself, prevented and reversed the TRH-induced stimulation of GH release, while TRH never antagonized the inhibitory effect of SRIF. We conclude that, in these adenomatous cells, the physiological inhibitory factor (SRIF) overcomes the nonphysiological stimulatory factor (TRH) in the control of GH secretion.
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PMID:Interaction between somatostatin and TRH on growth hormone secretion in perifused human growth hormone tumor cells. 286 Nov 54

The neuropeptide somatostatin inhibits hormone release from GH4C1 pituitary cells via two mechanisms: inhibition of stimulated adenylate cyclase and a cAMP-independent process. To determine whether both mechanisms involve the guanyl nucleotide-binding protein Ni, we used pertussis toxin, which ADP-ribosylates Ni and thereby blocks its function. Pertussis toxin treatment of GH4C1 cells blocked somatostatin inhibition of both vasoactive intestinal peptide (VIP)-stimulated cAMP accumulation and prolactin secretion. In membranes prepared from toxin-treated cells, somatostatin inhibition of VIP-stimulated adenylate cyclase activity was reduced and 125I-Tyr1-somatostatin binding was decreased more than 95%. In contrast, pertussis toxin did not affect the biological actions or the membrane binding of thyrotropin-releasing hormone. These results indicate that ADP-ribosylated Ni cannot interact with occupied somatostatin receptors and that somatostatin inhibits VIP-stimulated adenylate cyclase via Ni. To investigate somatostatin's cAMP-independent mechanism, we used depolarizing concentrations of K+ to stimulate prolactin release without altering intracellular cAMP levels. Measurement of Quin-2 fluorescence showed that 11 mM K+ increased intracellular [Ca2+] within 5 s. Somatostatin caused an immediate, but transient, decrease in both basal and K+-elevated [Ca2+]. Consistent with these findings, somatostatin inhibited K+-stimulated prolactin release, also without affecting intracellular cAMP concentrations. Pertussis toxin blocked the somatostatin-induced reduction of [Ca2+]. Furthermore, the toxin antagonized somatostatin inhibition of K+-stimulated and VIP-stimulated secretion with the same potency (ED50 = 0.3 ng/ml). These results indicate that pertussis toxin acts at a common site to prevent somatostatin inhibition of both Ca2+- and cAMP-stimulated hormone release. Thus, Ni appears to be required for somatostatin to decrease both cAMP production and [Ca2+] and to inhibit the actions of secretagogues using either of these intracellular messengers.
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PMID:Pertussis toxin blocks both cyclic AMP-mediated and cyclic AMP-independent actions of somatostatin. Evidence for coupling of Ni to decreases in intracellular free calcium. 286 57


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