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)

Mucosal cells were prepared by enzymatic digestion of porcine gastric mucosa with pronase and collagenase. The resulting cell suspension contained 10-15% parietal cells, which responded to histamine stimulation by an up to 20-fold increase in [14C]aminopyrine accumulation over control levels. Cholecystokinin-8 (CCK-8) evoked a more moderate stimulation of [14C]aminopyrine accumulation, whereas somatostatin inhibited histamine-stimulated accumulation. Parietal cells were enriched by elutriation and isopycnic centrifugation on density gradients of Percoll. A fraction with 60% parietal cells bound approximately three times more iodinated CCK-8 than a fraction containing 70% non-parietal cells. Binding of [125I]BH-CCK-8 to preparations containing 30-60% parietal cells was specifically inhibited to about 50% by 10(-9) M unlabelled CCK-8 but not by bombesin. Cell fractions containing about 30% parietal cells also bound [125I]somatostatin. Unlabelled somatostatin at 10(-9) M inhibited tracer binding by about 50%, while CCK-8 did not affect somatostatin binding to such a preparation. The results suggest the existence of specific receptors for CCK and somatostatin on porcine parietal cells exerting a regulatory influence on acid secretion.
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PMID:Binding of cholecystokinin and somatostatin to isolated porcine gastric mucosal cells and effects on aminopyrine uptake. 197 Feb 14

A primary culture of human antral somatostatin cells has been developed and used in release studies. The phorbol ester, phorbol 12 myristate 13-acetate, caused a concentration-dependent increase in immunoreactive somatostatin secretion with a 1-mumol/L concentration resulting in a 40-fold stimulation (basal 0.28% +/- 0.7% total cell content vs. 13.8% +/- 2.2% TCC, P less than 0.005). The calcium ionophore, A23187, resulted in a significant stimulation only at 1 mumol/L (basal 0.28% +/- 0.7% TCC vs. 2.2% +/- 0.5% total cell content, P less than 0.05). However, addition of the ionophore at 1 mumol/L with the phorbol ester resulted in a potentiation of the response at all concentrations tested. Removal of extracellular calcium by chelation with EGTA reduced the response to that seen with the phorbol ester alone. Forskolin at 0.1 mmol/L resulted in a five-fold increase (basal 0.6% +/- 0.2% total cell content vs. 2.8% +/- 0.9% total cell content, P less than 0.02) and was 1000-fold less potent than the phorbol ester. The peptides bombesin and gastrin at concentrations up to 1 mumol/L had no effect on basal secretion. Cholecystokinin-8 significantly stimulated somatostatin secretion with a maximal effect at 0.1 mumol/L resulting in an eightfold increase (basal 0.2% +/- 0.04% total cell content vs. 1.5% +/- 0.4% total cell content, P less than 0.02). These results indicate that human antral D cells are more responsive to agents acting through the c-kinase pathway (phorbol 12 myristate 13-acetate, A23187, and cholecystokinin) than adenylate cyclase (forskolin).
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PMID:Release of somatostatin immunoreactivity from human antral D cells in culture. 197 18

In the present study the effect of somatostatin on amylase secretion was determined using in vivo cannulation and isolated acini from rat pancreas. In vivo somatostatin-14 inhibited amylase secretion in basal state and that stimulated with CCK8 and acetylcholine. Somatostatin-14 and somatostatin-28 failed to inhibit amylase secretion from isolated acini in basal state and that stimulated with CCK8 and bethanechol. Somatostatin-14 did not increase 45Ca uptake or efflux of label from acini preloaded with 45Ca. Cellular cyclic AMP levels were not significantly increased. Somatostatin-14 did not alter the synthesis of proteins in vitro, as judged by incorporation of a mixture of fifteen 14C-labeled amino acids. Somatostatin-14 stimulated phosphoprotein phosphatase in higher doses, whereas no effect was observed at lower doses. Inhibition of secretion in vivo and lack of stimulation of amylase secretion in isolated acini suggest that the somatostatin effect in vivo is mediated by an indirect effect similar to other peptides, for example, opiates and neurotensin. Stimulation of phosphoprotein phosphatase suggests that somatostatin may bind to the acinar cells and affect functions other than secretion and synthesis of enzymes.
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PMID:Effect of somatostatin on amylase secretion from in vivo and in vitro rat pancreas. 242 87

A bland procedure, conducted in ice, is described for the extraction with HCl of smooth-muscle-contracting substances from plexus-containing ileal longitudinal muscle (l.m.) sheets obtained mainly from rabbits and some guinea-pigs. The spasmogenic activity in rabbit extracts was distinguished from acetylcholine, histamine and 5-hydroxytryptamine by antagonists; and from prostaglandins, by its insolubility in ether at acid pH and by pretreatment of the animals with indomethacin. The fact that it contracts the separated l.m. of the guinea-pig ileum, whether plexus-containing or plexus-free, and in atropine distinguishes it also from methionine-enkephalin, somatostatin, 13-norleucine motilin, bombesin, and cholecystokinin octapeptide (CCK8). This activity was partially purified, first by several partitions with ether at pH 1.4-2.2 and then by treatment at pH 4.5-5 with lead acetate. The virtual absence of ATP was confirmed by the firefly bioluminescence technique. The guinea-pig-ileum-contracting component in the partially purified extracts was destroyed by pepsin, chymotrypsin and DPCC-treated trypsin, indicating its peptide nature and distinguishing it from oxytocin, vasopressin, bradykinin, etc. In parallel assays the partially purified rabbit extracts were considerably more active than Substance P on jird or rat ascending colons than on the guinea-pig l.m., suggesting the presence of a second spasmogenic component in the extracts. In guinea-pig extracts the partially purified activity was 8-16 times greater when plexus-containing than when plexus-free, pointing to Auerbach's plexus as the source of the activity.
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PMID:Extraction and partial purification of spasmogenic substances in Auerbach's plexus. 242 21

There is increasing evidence that digestive hormones are involved in the regulation of the gastrointestinal motor profile in man. A typical profile of postprandial activity corresponding to the continuous occurrence of irregular contractions propagated over short distance is accompanied by an increase in plasma level of 8 to 10 identified digestive hormones. Four of them (insulin, gastrin, neurotensin and CCK8) infused systemically may produce or prolong this typical "fed" pattern suggesting that they may be involved physiologically in the initiation and duration of the fed pattern. The fasted state is characterized by the cyclic occurrence of gastrointestinal migrating motor complexes (MMC) which are associated with cyclic changes in plasma levels of motilin, somatostatin pancreatic polypeptide and gastrin. Numerous recent findings support the hypothesis that an increase in motilin initiates the MMC at foregut level which, in turn, produces the release of somatostatin. These hormones may be responsible for the aboral migration of MMC from the duodenum to the ileum and for the cycling rhythm by affecting blood levels of motilin (and/or) pancreatic polypeptide.
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PMID:[Hormonal control of intestinal motility]. 252 21

A detailed regional distribution of nerve cells and terminals immunoreactive to polypeptides or monoamines was examined in the 5 subdivisions (rostral, mid-dorsal, mid-ventral, caudo-dorsal and caudo-ventral parts) of the nucleus preopticus medianus (POMe) of the rat. In general, immunoreactive nerve cells and terminals are more numerous in the ventral parts of the middle and caudal POMe. Nerve cells immunoreactive to neurotensin (NT), Met-enkephalin-Arg6-Gly7-Leu8 (mENK8) or cholecystokinin-octapeptide (CCK8) are distributed throughout the POMe, while those immunoreactive to luteinizing hormone-releasing hormone (LHRH) are found in the rostral and middle POMe. Nerve cells immunoreactive to substance P (SP) are seen in the middle and caudal POMe and those immunoreactive to somatostatin (SRIF) are scattered in the middle part of the nucleus. The densities of nerve terminals immunoreactive to neuropeptide tyrosine, mENK8, SP or noradrenaline are high throughout the POMe, while nerve terminals immunoreactive to CCK8, LHRH, NT, SRIF or vasoactive intestinal polypeptide are moderate and those immunoreactive to calcitonin gene-related peptide, serotonin or dopamine are sparse. This varied distributional pattern of immunoreactive nerve cells and terminals suggests regional differences in function within the POMe.
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PMID:An immunohistochemical observation of polypeptides and monoamines in the nucleus preopticus medianus of the rat. 275 94

Somatostatin (SRIF) is a putative peptide neurotransmitter that may interact with brain capillaries following neurosecretion of the peptide. The present studies investigate the binding and metabolism of SRIF analogues in isolated bovine brain microvessels. 125I-[Tyr1]SRIF was rapidly degraded by capillary aminopeptidase with a half-time of approximately 3 min at 23 degrees C. The microvessel aminopeptidase had a low affinity and high capacity for the peptide, Km = 76 microM and Vmax = 74 nmol min-1 mgp-1. 125I-[Tyr11]SRIF was converted to free iodotyrosine at a much slower rate, presumably by a lower-activity endopeptidase. 125I-[Try11]SRIF was rapidly bound by microvessels, whereas another basic peptide, [Tyr8]bradykinin, or an acidic peptide, CCK8, or a neutral peptide, leucine enkephalin, were bound to a considerably less extent. The binding of 125I-[Tyr11]SRIF to the capillaries was nonsaturable up to a concentration of 1 microgram/ml of unlabeled peptide, and the binding reaction was extremely rapid, reaching equilibrium within 5 s at either 0 degrees C or 37 degrees C. Approximately 20% of the SRIF bound by the microvessels was resistant to acid wash and presumably represented internalized peptide. In addition, the 125I-[Tyr11]SRIF bound rapidly to the endothelial cytoskeleton remaining after a 1% Triton X-100 extraction of the microvessels. The peptide-cytoskeletal binding reaction was nonsaturable up to 1 microgram/ml of unlabeled [Tyr11]SRIF, but it was inhibited by 0.5% polylysine or 0.8 M KCl and was stimulated by 1 mM dithiothreiotol. These studies suggest that brain microvessels rapidly sequester and degrade SRIF analogues and that this may represent one mechanism for rapid inactivation of the neuropeptides subsequent to neurosecretion.
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PMID:Rapid sequestration and degradation of somatostatin analogues by isolated brain microvessels. 285 72

Neuropeptide Y (NPY) reduced the resting tension of the myenteric plexus-longitudinal muscle preparation (MP-LM) of the guinea-pig ileum (GPI). NPY in a dose-dependent manner also reduced the neurally-mediated excitatory effect of cholecystokinin octapeptide (CCK8) sulfated form on this preparation. However, NPY, at the concentration used in the study, did not modify the effect of exogenous acetylcholine (ACh). All these features were also shared by other inhibitory peptides, like somatostatin (SOM) and the enkephalin derivative FK 33-824. The preparation developed a degree of tachyphylaxis to the inhibitory effect of NPY more rapidly than it did to SOM. Moreover, the inhibitory effect of neuropeptide Y was of longer duration than the one seen for somatostatin. A faster metabolic rate might account for the lower development of tachyphylaxis to somatostatin. The presence of the opioid antagonist naloxone did not alter the inhibitory features of NPY or SOM. Therefore, the involvement of any endogenous opioid in the action of these two inhibitory peptides can be disregarded.
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PMID:Neuropeptide Y is an inhibitor of neural function in the myenteric plexus of the guinea-pig ileum. 287 16

Somatostatin binding to its receptors on rat pancreatic acinar membranes was characterized with [125I-Tyr1]somatostatin. The COOH-terminal octapeptide of cholecystokinin (CCK8), when present at various concentrations in the reaction mixture for the binding study, reduced labeled somatostatin binding in a dose-dependent manner, whereas carbachol or Ca2+ ionophore did not affect the binding. By contrast, when pancreatic acini were first treated with carbachol and thereafter [125I-Tyr1]somatostatin binding to membranes prepared from these acini was examined, carbachol reduced subsequent somatostatin binding in a dose-dependent manner. Scatchard analysis of the labeled somatostatin binding revealed that carbachol pretreatment decreased the maximum binding capacity from 142 +/- 20 fmol/mg of membrane protein to 63.5 +/- 3.5 fmol/mg of membrane protein without significantly affecting the binding affinity. To test for the possibility that CCK8 also may affect labeled somatostatin binding through an intracellular process, pancreatic acini were first treated with CCK8 and then the membrane bound CCK8 was washed out. Subsequent labeled somatostatin binding to membranes from these acini was also decreased. When 1 mM EDTA was present in the pretreatment medium, the inhibitory effect of carbachol or CCK8 was partially abolished, suggesting that an intracellular process to modulate somatostatin binding is dependent on Ca2+. On the other hand, pretreatment of acini with Ca2+ ionophore almost failed to affect subsequent labeled somatostatin binding. Results therefore suggest that CCK8 can modulate labeled somatostatin binding to pancreatic acinar membranes not only acting through an intracellular process but also at membrane sites and carbachol- or CCK8-activated intracellular process to modulate somatostatin binding is dependent on Ca2+, but Ca2+ mobilization itself is not sufficient to affect subsequent somatostatin binding.
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PMID:[CCK and carbachol differently modulate somatostatin binding to rat pancreatic acinar membranes]. 287 7

The effects of pretreatment with pancreatic secretagogues and subsequently activated cellular events on [125I-Tyr1] somatostatin binding to acinar membranes were studied. Pretreatment of pancreatic acini with bombesin at increasing concentrations for 120 min reduced labeled somatostatin binding to the acinar membranes in a dose-dependent fashion with a maximal reduction of binding at 10(-8)M bombesin (44.3 +/- 1.8% of control). The maximal inhibition of labeled somatostatin binding by pretreatment with bombesin was almost comparable to that with COOH-terminal octapeptide cholecystokinin (CCK8) or carbamylcholine (carbachol). Furthermore, pretreatment of acini with vasoactive intestinal peptide (VIP) as well as secretin resulted in a small, but significant decrease of subsequent labeled somatostatin binding. In addition, adenosine 3', 5' cyclic nucleotide derivatives or a phosphodiesterase inhibitor mimicked the effect of VIP or secretin. The effect of simultaneous pretreatment of acini with VIP and carbachol on subsequent labeled somatostatin binding appeared to be almost equal to the calculated additive value for each peptide. These results suggest that the binding of somatostatin to its receptors in the pancreatic acini may be regulated via two functionally distinct pathways.
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PMID:[Effects of various pancreatic secretagogues on somatostatin binding to rat pancreatic acinar cell plasma membranes]. 288 Jul 53


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