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 effects of somatostatin (SOM) and cholecystokinin octapeptide (CCK-8) on basal and potassium-induced release of acetylcholine (ACh) were investigated in slices of rat caudate nucleus (CN) and, for comparison, cerebral cortex (CX). Potassium (5-55 mM) produced a concentration-dependent increase in the release of [3H]ACh in the presence of extracellular Ca2+. SOM (1 microM), CCK-8 (1 microM) and the dopamine (DA) receptor agonist, apomorphine (APO, 30 microM) inhibited the K+-induced (35 mM) release of [3H]ACh by 26-32% from CN, but did not affect ACh release from CX. Other peptides (1 microM), such as Met-enkephalin, vasoactive intestinal peptide, thyrotropin-releasing hormone and substance P, had no effect on release of [3H]ACh in CN or CX. Sulpiride (SULP), a dopamine receptor antagonist, prevented the effects of APO and SOM, but not CCK-8, to inhibit [3H]ACh release. The results indicate that: (1) SOM and CCK-8 inhibit the release of [3H]ACh in CN, but not CX; and (2) the inhibitory effect of SOM, but not CCK-8, on [3H]ACh release is mediated by dopaminergic mechanisms.
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PMID:Somatostatin and cholecystokinin octapeptide differentially modulate the release of [3H]acetylcholine from caudate nucleus but not cerebral cortex: role of dopamine receptor activation. 287 39

Previous work showed beta h-endorphin inhibits glucose-stimulated secretion of insulin by rabbit pancreas slices. This study, also conducted with rabbit pancreas slices, compared the antisecretagogue actions of beta h-endorphin, somatostatin 1-14, and epinephrine versus four secretagogues, glucose, mannose, leucine and potassium chloride. All three antisecretagogues inhibited all four secretagogues. The order of potency of the antisecretagogues varied according to secretagogue. Naloxone antagonized only beta h-endorphin among the three antisecretagogues, and phentolamine antagonized only epinephrine.
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PMID:Effect of beta h-endorphin on release of insulin by rabbit pancreas in response to four secretagogues: comparison with somatostatin and epinephrine. 287 7

Vasoactive intestinal polypeptide (VIP), originally isolated from the porcine small intestine, is known to be widely distributed throughout the body including the central and peripheral nervous systems in various species. In the present study, we demonstrated the existence, subcellular distribution and mode of release of VIP-like immunoreactivity (VIP-LI) in the bovine adrenal medulla by radioimmunoassay. In tissue extracts from fresh bovine adrenal medulla, a considerable amount of VIP-LI (101.1 +/- 24.3 ng/g wet weight) was detected, and its concentration was about 100 times and 30 times higher than those of neurotensin-LI and somatostatin-LI, respectively, on a molar basis. On chromatographic analysis, the majority of adrenal VIP-LI was comfirmed to have the same molecular size as synthetic VIP, and a small peak of macromolecular VIP-LI corresponding to pro-VIP was also found. In studies using a retrograde venous perfusion system of the bovine adrenal gland, marked releases of both VIP-LI and catecholamine (CA) were observed immediately after the infusion of potassium solution of a concentration of 56 mM in a Ca2+-dependent manner. Ba2+ (2 mM) also stimulated the releases of VIP-LI and CA from the adrenal gland Carbachol (10(-4)M) stimulated CA secretion as much as high potassium and Ba2+, but the magnitude of VIP-LI release was lower. The subcellular distribution of VIP in the adrenal medulla was investigated by a method of differential centrifugation and discontinuous density gradient. VIP-LI was mainly found in mitochondrial fraction, which contain mitochondria and synaptosome, while little was found in highly purified chromaffine granule fraction. These results suggest that VIP in the adrenal gland is mainly localized in the splanchnic nerve endings and may play a role as neurotransmitter/neuromodulator in the adrenal medulla.
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PMID:[The localization and release of immunoreactive vasoactive intestinal polypeptide (VIP) in the bovine adrenal medulla]. 287 48

We investigated the effect of several potential carbohydrate secretagogues, amino acids, a ketoacid, and potassium chloride on insulin, glucagon, and somatostatin release from the in vitro perfused Brockmann body of channel catfish (Ictalurus punctatus). Mannose (15 mM) stimulated the release of insulin and somatostatin. Fructose (30 mM) induced only a small and transient release of somatostatin. Galactose (15 mM) was not a secretagogue. Likewise, glyceraldehyde failed to stimulate hormone release. Among the amino acids newly tested, alanine and leucine, and also alpha-ketoisocaproic acid were without effect. A high concentration of potassium (25 mEq/liter) induced a pronounced release of insulin and glucagon and a moderate release of somatostatin. In conclusion, a striking similarity exists between catfish and higher vertebrates in their pancreatic endocrine response to hexoses; on the other hand, the catfish Brockmann body appears to respond only to a few of the common stimuli of pancreatic hormone release in mammals.
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PMID:Secretagogues for pancreatic hormone release in the channel catfish (Ictalurus punctatus). 288 40

We have assessed the effect of somatostatin on glucose-, potassium-, forskolin-, and dibutyryl cAMP-induced changes in cytosolic free [Ca2+] in normal rat pancreatic islet cells with the new Ca2+ indicator fura 2. The cytosolic free [Ca2+] in islet cells incubated with nonstimulatory concentrations of glucose (30 mg/dl) ranged from 54 to 64 nM. In the presence of extracellular Ca2+ (1 mM), glucose (300 mg/dl) rapidly increased the cytosolic free [Ca2+] to a level of 90-110 nM. In the absence of extracellular Ca2+, glucose failed to increase the cytosolic free [Ca2+], which remained at a level of 55-60 nM. Somatostatin inhibited glucose-induced increases in cytosolic free [Ca2+] in a dose-dependent manner (maximal inhibition was 34%). Half-maximal inhibition was observed at 10(-9) M somatostatin, which correlated well with somatostatin binding to islet cells (Kd = 2.6 X 10(-10) M). Potassium (50 mM) rapidly increased the cytosolic free [Ca2+] to 110-120 nM, and its effect was not influenced by the presence of somatostatin. Forskolin (20 microM) and dibutyryl cAMP (1 mM) rapidly increased cytosolic free Ca2+ both in the presence and absence of extracellular Ca2+. More than 80% of the overall increase in cytosolic free-Ca2+ levels could be accounted for by the mobilization of intracellular Ca2+ stores. Somatostatin effectively blocked the forskolin effect (32% inhibition) but not the dibutyryl cAMP-induced effect. Somatostatin appears to inhibit secretagogue-induced increases in cytosolic free [Ca2+] by interfering with cAMP production and probably with Ca2+ transport across the cell membrane.
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PMID:Cytosolic free-calcium concentrations in normal pancreatic islet cells. Effect of secretagogues and somatostatin. 288 56

Cholecystokinin (CCK) is one of the most abundant neuropeptides in the rat caudatoputamen (cp). CCK perikarya innervating cp are thought to originate in neurons in the claustrum/piriform cortex area of the amygdala. Previous studies on the release of CCK from cp have focused on the influence of dopamine agonists. The present study has examined the influence of other neuroactive substances on the release of CCK. The release of CCK from rat cp slices in vitro stimulated by potassium was quantitated with a specific CCK radioimmunoassay. This potassium-stimulated release of CCK was Ca2+-dependent. Maximal stimulation of CCK release was observed at 55 mM potassium. Several lines of evidence indicate that the release of CCK from cp is inhibited by some other substance (or substances) released by a Ca2+-dependent mechanism from cp along with CCK. Release media from cerebral cortex or cp (called 'conditioned media' or CM) inhibits the release of CCK from fresh slices of cp but not from cerebral cortex. The release of dopamine from cp is unaffected by CM from cortex or cp. The identity of the substance in CM which inhibits CCK release from cp is still under investigation, though it appears not to be CCK, dopamine, acetylcholine, somatostatin, leucine enkephalin or gamma-aminobutyric acid.
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PMID:The regulation of cholecystokinin release from rat caudatoputamen in vitro. 288 11

LHRH has previously been found to be the only known hypothalamic releasing factor which can specifically stimulate the release of the opioid dynorphin and other proenkephalin B-derived peptides from the rat adenohypophysis in vitro. In the present study the mechanisms that regulate dynorphin release were further characterized. It was examined whether or not dynorphin release from the adenohypophysis in vitro is altered during inhibition of the secretion of various anterior pituitary hormones. Rat anterior pituitary quarters were incubated in vitro and hormone release into the incubation medium was measured by RIAs. Somatostatin, dopamine, T3, dexamethasone, and 5 alpha-dihydrotestosterone were used to inhibit the secretion of GH, PRL, TSH, ACTH/beta-endorphin, or LH/FSH, respectively. GH, PRL, or beta-endorphin release was inhibited without affecting the simultaneous release of dynorphin A-(1-13)-like immunoreactivity (Dyn A1-13-IR). Concentrations of T3, somatostatin, or dopamine which were effective in suppressing the evoked and/or basal release of TSH, GH, or PRL, respectively, produced no effect on Dyn A1-13-IR release caused by high potassium concentration (40 mM) or LHRH (500 pM). The LHRH-induced release of LH and FSH was inhibited by the glucocorticoid dexamethasone or the androgen 5 alpha-dihydrotestosterone. Under these conditions, Dyn A1-13-IR release was also reduced. However, whereas LH release was completely blocked by 5 alpha-dihydrotestosterone, FSH and Dyn A1-13-IR release was reduced only by 50%. The release of FSH and Dyn A1-13-IR in vitro from anterior pituitary glands taken from rats, castrated 3 weeks before, was enhanced to a similar extent (about 2.5-fold); the simultaneous enhancement of LH release was significantly (P less than 0.005) greater (about 5-fold). We conclude that the mechanisms which regulate the release and/or biosynthesis of dynorphin and other proenkephalin B-derived peptides of the adenohypophysis are similar to those of the gonadotropins but different from those of any other anterior pituitary hormone, and may be more closely related with FSH release than LH release. These data support the view that dynorphin of the normal rat adenohypophysis may be localized in at least a subpopulation of gonadotrophs.
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PMID:Release of dynorphin-like immunoreactivity from rat adenohypophysis in vitro during inhibition of anterior pituitary hormone secretion from individual cell types. 288 74

During in vitro incubation of rat mediobasal hypothalamus (MBH), potassium and sodium gradients were high in the presence of glucose, pyruvate, lactate or the mixture glucose and pyruvate; in the absence of substrate, the ionic gradients were markedly lowered and corresponding somatostatin release from MBH was maximal. The specific effect of glucose on somatostatin release from MBH was tested under normal tissue polarization, i.e. in the presence of pyruvate. Under these more physiological conditions, somatostatin release was submaximal and inversely related to glucose concentrations (within the range 0-7 mM).
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PMID:Further studies on the effect of glucose concentrations and other oxidizable substrates upon ionic gradients and in vitro somatostatin release from rat mediobasal hypothalamus. 289 59

Immunocytochemical and electrophysiological evidence suggests that somatostatin may be a transmitter in the hippocampus. To characterize the ionic mechanisms underlying somatostatin effects, voltage-clamp and current-clamp studies on single CA1 pyramidal neurons in the hippocampal slice preparation were performed. Both somatostatin-28 and somatostatin-14 elicited a steady outward current and selectively augmented the noninactivating, voltage-dependent outward potassium current known as the M-current. Since the muscarinic cholinergic agonists carbachol and muscarine antagonized this current, these results suggest a reciprocal regulation of the M-current by somatostatin and acetylcholine.
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PMID:Somatostatin augments the M-current in hippocampal neurons. 289 68

The effect of somatostatin (SS-14) was tested in an anesthetized rabbit model of closed-loop ileal obstruction. Experimental groups included (1) immediate treatment (N = 6) receiving SS-14 2,000 pmol X kg-1 X h-1 intravenously (I.V.) beginning at the time of ileal obstruction, (2) delayed treatment (N = 5) receiving SS-14 beginning 6 hours following ileal obstruction, and (3) control (N = 6) receiving only hydration. After 24 hours, all rabbits were killed. Significantly decreased intestinal luminal volume and sodium and potassium output was observed with both immediate and delayed SS-14 treatment when compared to control. Additionally, the gross and microscopic pathologic features of intestinal distension, inflammation, and necrosis seen in control rabbits were absent in rabbits treated with SS-14. The known broad spectrum of physiologic activity of SS-14 on the gastrointestinal tract appeared beneficial in this rabbit model of intestinal obstruction.
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PMID:The effect of somatostatin on experimental intestinal obstruction. 289 93


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