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)

This study was aimed at evaluating the effect of theophylline, a drug that increases the intracellular concentrations of cAMP by inhibiting phosphodiesterase activity, on somatostatin (SRIF)-mediated inhibition of insulin secretion in man. Acute insulin response (AIR) to i.v. glucose (mean change 3-10 min) was almost totally suppressed by SRIF (500 micrograms/h) and glucose utilization was reduced (p less than 0.0001). These SRIF-induced decreases failed to be eliminated by a concurrent infusion of theophylline (100 mg as a loading dose followed by a constant infusion of 5 mg/min). Theophylline alone resulted in a significant increase in both AIR (p less than 0.01) and glucose removal rates (p less than 0.05). Thus, our data disprove the involvement of the phosphodiesterase enzymes in the inhibitory action of SRIF on glucose-induced insulin secretion in man.
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PMID:Somatostatin and insulin secretion in man. II. The effect of theophylline. 4 65

The effect of somatostatin (SRIF) on human chorionic somatomammotropin (hCS) secretion was studied in human placental explants cultured in vitro. In the experimental flasks, SRIF was added in a concentration of 10, 100, and 1000 ng/ml media; hCS levels measured by RIA were not different from those found in the control flasks. In separate experiments, we investigated the action of SRIF on hCG secretion by a human malignant choriocarcinoma cell line maintained in tissue culture. SRIF (1000 ng/ml) did not inhibit basal or dibutyryl cAMP-induced stimulation of hCG secretion. These results suggest that somatostatin does not suppress hCS or hCG release in vitro from normal or malignant trophoblast, respectively.
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PMID:Failure of somatostatin to affect human chorionic somatomammotropin and human chorionic gonadotropin secretion in vitro. 4 71

A radioimmunoassay (RIA) method for somatostatin (SRIF) utilizing rabbit antiserum against synthetic SRIF coupled with human serum alpha-globulin is described. Synthetic N alpha-tyrosylated SRIF was labelled with 125I using the lactoperoxidase method and purified on a Sephadex G-10 column. This assay system was highly specific for SRIF and did not cross-react with hypothalamic trophic hormones, pituitary trophic hormones or gastrointestinal hormones. The effect of streptozotocin induced diabetes on the SRIF content was examined in the pancreas, the pancreatic islets, as well as the hypothalamus of rats. SRIF content in both the pancreas and islets of the diabetic rats was shown by RIA to have significantly increased. However, content in the hypothalamus of the diabetic rats did not differ from that of the control. The physiological and pathophysiological significance of the SRIF changes remains to determined.
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PMID:Effect of streptozotocin administration on somatostatin content of pancreas and hypothalamus in rats. 14 51

By the enzyme-labeled antibody method, cells containing somatostatin (SRIF) as well as insulin or glucagon were identified in pancreatic islets of the rat. SRIF antiserum was raised in rabbits followin immunization with synthetic SRIF coupled with human serum alpha-globulin and did not cross-react with hypothalamic, pituitary or gastrointestinal hormones using our immunoassay method. In the control rats, SRIF-containing cells were scattered in the periphery of the islets in close proximity to the outer glucagon containing cells. These latter cells were distributed in the outermost periphery of the islets. Insulin-containing cells were located in the central portion of the islets and dominantly occupied most of the islet. In the streptozotocin-diabetic rat, SRIF-containing cells were significantly increased in number whereas insulin-containing cells were markedly reduced. It is suggested from these findings that the number as well as the distribution of SRIF-, insulin- and glucagon-containing cells was important to the physiological and pathophysiological functioning of the islet.
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PMID:Immunohistochemical changes of somatostatin cells in the pancreatic islets of rats after streptozotocin administration. 14 56

The large intestine resected from 6 Hirschsprung's patients and surgical colonic biopsies from 6 control children were examined with light and electron microscopy. The presence and the relative distribution of various endocrine cell types in both groups of mucosa were determined. In light microscope studies endocrine cell data were expressed as number of cells per unit area of mucosa using a quantitative method after argentaffin and Grimelius's argyrophilic techniques and an immunoperoxidase reaction with glucagon and somatostatin (SRIF) antisera. The results indicate that endocrine cells are apparently not involved in Hirschsprung's disease, since their number and frequency did not differ significantly between the ganglionic and aganglionic segments of Hirschsprung's patients nor between the latter and control children. Glucagon immunoreactive cells were, on the average, 5-6 times and 7-9 times more numerous that SRIF cells in the rectum and the sigmoid, respectively. Ultrastructurally, five endocrine cell types could be distinguished. The fifth type, probably a transition type, apparently disappears in adults.
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PMID:Endocrine cells of the colon in Hirschsprung's and control children. 15 Jan 4

The hypothalamic hormones, somatostatin (SRIF or GH-RIH) and thyrotropin releasing hormone (TRH) applied intraventricularly into rat brain had a considerable effect on motor function and resulted in profound alterations in the sleep-waking pattern. While TRH induced primarily an increase in exploratory and motor stereotyped behavior, the effect of somatostatin was striking and prolonged: stereotyped circular running in many instances evolved into catatonia, paraplegia-in extension and/or tonic-clonic seizures.
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PMID:Somatostatin and thyrotropin releasing hormone: central effect on sleep and motor system. 18 May 47

Since growth hormone (GH) and prolactin (Prl) secretion by human pituitary tumours is often influenced by the hypophysiotrophic hormones thyrotrophin-releasing hormone (TRH) and somatostatin (SRIF), we have examined the responses of several transplantable rat pituitary tumours to these substances in a perifusion apparatus. The MStT/W15 tumour did not alter its secretion of GH and Prl in response to TRH, SRIF, or a partially purified porcine hypothalamic extract containing GH-releasing activity; normal rat pituitaries show clear responses to each of these substances. Theophylline and dibutyryl cyclic AMP each provoked increased GH and Prl release from the tumour. A second specimen of the MStT/W15 tumour and a specimen of the MStT/W5 tumour behaved in a manner identical to the original MStT/W15, showing no response to TRH or SRIF, but releasing both GH and Prl when theophylline or dibutyryl cyclic AMP was given. The MtT/F4 tumour increased its secretion of GH in response to TRH, 10 mug/ml, and theophylline, but no effect was seen with lower concentrations of TRH or with SRIF; Prl secretion by the F4 tumour was increased by theophylline, but TRH and SRIF had no effect. The autonomy demonstrated in these experimental tumours may be due to a loss of specific hypophysiotrophic hormone receptors or of secretory activating mechanisms.
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PMID:Altered responsiveness to hypophysiotrophic hormones of perifused rat pituitary tumours. 19 Aug 40

The influence of somatostatin (SRIF) on blood glucose, plasma insulin and plasma glucagon was studied in hamsters bearing a transplantable islet-cell tumor secreting insulin and glucagon as well as in normal controls. Fed anesthetized animals were infused intraperitoneally either at a dose of 10 microgram in 15 min or of 150 microgram in 30 min, and intravenously at a dose of 250 microgram in 30 min. Blood was withdrawn from the jugular vein before and after infusion. Before the infusions, tumor bearing animals (TB) had lower blood glucose, markedly elevated plasma glucagon and slightly lower plasma insulin by comparison with normal hamsters (N). Both doses of somatostatin infused by the intraperitoneal route produced a slight but significant hypoglycemia in TB hamsters but not in normals. Ten microgram SRIF did not affect insulin and plasma glucagon levels whereas 150 microgram SRIF significantly depressed plasma insulin in both types of hamsters (N and TB). This latter dose of SRIF decreased plasma glucagon in normal but not in tumor-bearing hamsters. Intravenous infusion of 250 microgram SRIF did not reduce the hyperglucagonemia of TB hamsters either. These results indicate that somatostatin does not reduce the hyperglucagonemia due to the transplantable islet-cell tumor but nevertheless decreases blood glucose and plasma insulin.
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PMID:Effect of somatostatin in the Syrian hamster bearing a transplantable islet-cell tumor. 20 96

Neuronal compartments can be separated by differential spinning or by centrifugation on continuous or discontinuous density gradients. Application of these fractionation techniques to brain structures containing neurosecretory neurons shows that LHRH, somatostatin and a non dopamine prolactin inhibiting factor (PIF) are exclusively recovered from synaptosomal fractions. This indicates that biologically and/or immunologically reactive forms of these hormones are almost entirely concentrated in nerve-endings of neurosecretory neurons. In contrast, other neuropeptides - posterior pituitary hormone, but also TRH, a vasoactive intestinal peptide (VIP), substance P or endorphins - are also found in supernatant fractions. The existence of multiple molecular forms of neuropeptides is likely to explain these differences. Current theories postulate that they are synthetized on ribosomes as precursor forms. Their active structure is only achieved by enzymatic splitting of the pre- or the prohormone within nerve endings. This mode of synthesis is probably common to all neuropeptides, although it has only been well substantiated in a few cases, in particular for the hormones of the posterior pituitary. Thus, the lack of immunologically detectable LHRH or SRIF outside the synaptosomal fraction may reflect masking of the active immunological sites by inert peptide chains associated with prohormonal forms. Fractionation methods can also be applied to physiological or pharmacological experiments. In particular, they permit to characterize, on presynaptic membranes of neurosecretory neurons, specific receptors to neurotransmitters involved in the control of neurohormone secretion. Interaction of dopamine and acetylcholine with LHRH and CRF release are presented as examples of such applications.
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PMID:[Subcellular distribution of hypothalamic neurohormones and in vitro stimulation of their release]. 20 91

The inhibition by somatostatin (SRIF) of basal and arginine-stimulated glucagon, insulin, and glucose levels was compared with that obtained when SRIF was preceded by alpha-adrenergic blockade with phentolamine. No noteworthy differences were observed, except that the characteristic rebound of insulin upon discontinuation of SRIF was significantly lower with phentolamine (P less than 0.01). These results indicate that inhibition of basal and arginine-stimulated glucagon and insulin secretion by SRIF in man is not mediated through activation by alpha-adrenergic receptors.
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PMID:Phentolamine and the action of somatostatin in man. 21 13


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