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)

Somatostatin-related peptides act within the central nervous system to influence adrenomedullary epinephrine secretion and thermoregulation. Cysteamine-induced depletion of brain somatostatin-related peptides or central administration of a somatostatin receptor antagonist alters adrenomedullary epinephrine secretion and thermoregulation in a predictable manner. The actions of cysteamine and the somatostatin receptor antagonist are reversed by administration of somatostatins into the central nervous system, supporting the hypothesis that endogenous brain somatostatin-related peptides are involved in the regulation of adrenomedullary epinephrine secretion and thermoregulation.
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PMID:Central nervous system actions of somatostatin-related peptides. 286 33

Cysteamine (CSH; beta-mercaptoethylamine) is known to deplete pancreatic somatostatin without affecting the insulin or glucagon content. It may therefore be useful for studies of intra-islet regulation of hormone release. In the present study injection of CSH (60 mg/kg body weight) to mice decreased the somatostatin content of their isolated pancreatic islets to 50% in 1 h and 30% in 4 h as compared to islets of non-injected controls. Exposure of isolated mouse islets to CSH (100 micrograms/ml) for either 0.5 h followed by incubation in control medium for 3.5 h, or continuously for 4 h, decreased the somatostatin content to about 40% of the controls. There was no change in the islet content of insulin or glucagon. Islets pretreated with CSH (100 micrograms/ml) for 1 h in vitro showed a decreased glucose stimulation of both oxygen consumption and glucose oxidation. Measurements of insulin release after a similar preincubation of the islets indicated an increased basal release and an attenuated glucose stimulation. It is concluded that CSH rapidly decreases islet somatostatin both in vivo and in vitro. This depletion may lead to a loss of tonic inhibition by islet somatostatin on basal insulin release. It is, however, more plausible that the increased basal insulin release reflected a direct effect of CSH on the islet beta-cells.
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PMID:Rapid depletion of somatostatin in isolated mouse pancreatic islets after treatment with cysteamine. 286 62

The effects of prior treatment with cysteamine, a drug which appears to deplete selectively the neuropeptide somatostatin, on apomorphine-induced stereotypy and amphetamine-induced locomotor activity and conditioned place preferences were investigated. Twelve hours following systemic cysteamine injections apomorphine-induced stereotypy was attenuated and striatal somatostatin levels were reduced by half. Systemic cysteamine also decreased the motor stimulant effects of amphetamine, without influencing the rewarding properties as determined by the conditioned place preference procedure. Direct injections of cysteamine into the nucleus accumbens also decreased the locomotor response to amphetamine, and produced a local reduction in somatostatin levels in the accumbens. Cysteamine did not appear to alter monoamine turnover in the striatum after either systemic or intra-accumbens injections. These results suggest that somatostatin in the nucleus accumbens and caudate-putamen modulates the motor, but not the reinforcing properties of dopaminergic drugs, possibly via an action postsynaptic to dopamine-releasing terminals. Furthermore, it is evident from these results that cysteamine is an important tool with which to study the central actions of somatostatin.
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PMID:The effects of cysteamine on dopamine-mediated behaviors: evidence for dopamine-somatostatin interactions in the striatum. 287 68

The binding and the insulinotropic effects of enkephalin analogs and of morphine were investigated in rat pancreatic islets. Binding of [3H]Met-enkephalin was saturable, specific and reversible; the rank order for inhibition competition of [3H]Met-enkephalin binding by various compounds was Met-enkephalin = D-Ala2-MePhe4, Met(0)ol enkephalin) greater than Leu-enkephalin greater than morphine with half-maximal inhibitory constants (IC50) of approx. 0.3, 0.3, 100 and greater than 100 nM, respectively. Both the natural enkephalins exerted their insulinotropic effect only at stimulatory glucose concentrations. They had a dual action; whereas insulin secretion was increased at low enkephalin concentration, this effect was reversed at higher concentrations. However, the various enkephalins exerted this effect at different concentrations; only the EC50 values (half-maximal effective concentrations) of their insulinotropic effect were in the same range as the IC50 values of inhibition of [3H]met-enkephalin binding. Cysteamine pretreatment of rats (depletion of somatostatin containing D-cells and decrease in somatostatin secretion) did not change the Met-enkephalin effect on insulin secretion. In contrast to Met-enkephalin, binding of [3H]morphine to islets was not saturable, and morphine had no effect on insulin secretion unless at unphysiologically high concentrations. The data, therefore, indicate that: mu-receptors (affinity for morphine) do not play a role in rat pancreatic islets; delta-receptors (binding site for Met-enkephalin when mu-receptors are not present) mediate the insulinotropic effect of low Met-enkephalin concentrations; and the insulinotropic action of Met-enkephalin is not mediated indirectly via the paracrine effect of an inhibition of somatostatin secretion.
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PMID:The significance of mu- and delta-receptors in rat pancreatic islets for the opioid-mediated insulin release. 287 36

Physostigmine, oxotremorine, RS-86, and a combination of piracetam and lecithin, have all been studied in patients with Alzheimer's disease. Intravenous physostigmine produced a significant improvement in patients' ability to recognize words and particularly to distinguish words they had never seen before from words previously presented. A subgroup of Alzheimer's patients had a clinically meaningful improvement to treatment with oral physostigmine, with the degree of improvement correlating with the ability of oral physostigmine to increase the nocturnal secretion of cortisol. No statistically significant differences of piracetam or piracetam and lecithin, compared to placebo were noted, however, the ratio of red cell to plasma choline might be associated with treatment responsivity. The potential therapeutic efficacy of oxotremorine proved all but impossible to assess due to concomitant adverse effects, particularly dysphoria. Results with another cholinergic agonist, RS-86, will be reported. This drug appeared to be better tolerated than oxotremorine. Animals with a kianic acid induced cortical depletion of choline acetyltransferase were found to have a significant impairment in retention of a passive avoidance task, an abnormality that was readily reversible by physostigmine, oxotremorine and 4-amino-pyridine. Cysteamine, a depletor of somatostatin, also produced a comparable deficit.
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PMID:Animal models of Alzheimer's disease: behavior, pharmacology, transplants. 287 11

We investigated the effects of cysteamine on the pancreatic islet hormones and found that pancreatic somatostatin contents depleted 60 min after the oral administration of cysteamine (300 mg/kg) to rats, yet the insulin and glucagon contents remained unchanged. When pancreatic islets isolated by collagenase digestion were incubated for 60 min in Krebs-Ringer bicarbonate buffer containing 0.1, 1, or 10 mM cysteamine, cysteamine dose-dependently decreased the somatostatin content, however, only a high concentration (10 mM) decreased the insulin level, and cysteamine exerted no effect on the glucagon content. The islet hormones (synthetic somatostatin-14, synthetic somatostatin-28, extracted pork insulin and extracted pork glucagon) were incubated for 60 min with cysteamine (0.1, 1, or 10 mM) and somatostatin-14 was found to be markedly decreased by 1 mM cysteamine. Pork insulin but not pork glucagon was dose-dependently decreased by 0.1-10 mM cysteamine. Cysteamine, 0.1-1 mM, did not interfere with the radio-immunoassay system for somatostatin or insulin, although 10 mM cysteamine did so. This compound exerted no effect on the radioimmunoassay system for glucagon. Our studies support earlier findings that cysteamine administered to experimental animals plays a role of relatively specific depletor of somatostatin. The possibility that the depletion of somatostatin is in part due to the remarkable sensitivity of the intracellular compartments of the D cells to the drug and in part due to the remarkable sensitivity of the molecular structure of somatostatin has to be considered.
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PMID:Mechanisms involved in the depleting effect of cysteamine on pancreatic somatostatin. 288 72

The brain and spinal cord of untreated and cysteamine-treated rats were analyzed with immunohistochemistry using antisera raised against somatostatin (SOM)-28(1-14) and SOM-28(15-28). Sections incubated with increasing dilutions of antiserum were evaluated subjectively on coded slides and with computer-assisted image analysis. For control experiments, antisera raised against methionine-enkephalin, neuropeptide Y (NPY) and dynorphin (DYN)(1-13) were used. The latter antiserum does not visualize the conventional DYN systems in the brain, but reacts with an unknown epitope, which here could be shown to be present in SOM neurons. In cysteamine-treated rats a marked decrease in SOM-28(15-28)-like immunoreactivity (1.1) could be recorded subjectively at all antibody concentrations in fibers in several brain areas, including nucleus accumbens, tuberculum olfactorium and the hypothalamic ventromedial and arcuate nuclei. In these areas SOM-LI is fairly weak in untreated rats. In SOM-rich regions such as the median eminence and the dorsal horn of the spinal cord, the depleting effect of cysteamine could be recorded subjectively only when diluted antisera were used. Image analysis confirmed the subjective analysis, and, in addition, differences between controls and cysteamine-treated rats could be shown also at high antiserum concentrations. SOM-28(15-28)-immunoreactive cell bodies could be seen in the brains of either control or drug-treated rats. No effect of cysteamine could be observed when antiserum raised to SOM-28(1-14) was used. Cysteamine did not seem to affect enkephalin-LI, NPY-LI or an epitope in SOM neurons reacting with DYN(1-13) antiserum. After preabsorption of SOM-28(15-28) antiserum with SOM-28(15-28) peptide, the staining patterns described above disappeared completely. However, if the SOM-28(15-28) peptide was pretreated with a high concentration (1 M) of cysteamine before being used for absorption with SOM antiserum, no blocking effect could be observed. The present results demonstrate with immunohistochemistry that cysteamine causes depletion of SOM-28(15-28) in fibers but apparently not in cell bodies. No effects on SOM-28(1-14)-LI were observed. This supports earlier evidence that cysteamine interacts with the disulphide bond in the SOM-28(15-28) molecule. The present results also emphasize that when analyzing drug effects on peptide neurons with immunohistochemical techniques, it is important to use dilution series of antibodies and preferably to carry out the analysis with objective image analysis methods.
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PMID:Immunohistochemical analysis of the effects of cysteamine on somatostatin-like immunoreactivity in the rat central nervous system. 288 49

Cysteamine is known to deplete the immunoreactive somatostatin content in different organs from rat and mouse. The aim of the present work was to test if cysteamine also affects the somatostatin content in guinea-pig islets, since guinea-pigs have a carbohydrate metabolism different from that of other laboratory animals. Cysteamine was injected to guinea-pigs and the pancreatic islets were isolated four hours later. Cysteamine was also incubated in vitro with isolated pancreatic islets from untreated guinea-pigs. Cysteamine depleted the somatostatin content in the pancreatic islets in both the in vivo and in vitro studies.
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PMID:The effect of cysteamine on the somatostatin content of guinea-pig islets. 288 64

The role of the neuropeptide somatostatin in limbic seizures was studied using electrical stimulation of the hippocampus in kindled rats. Cysteamine, an agent which selectively and reversibly depletes brain somatostatin stores, had a biphasic action. An early proconvulsant effect was seen within a few hours, consisting of prolonged electrographic seizures in the hippocampus and more severe behavioral convulsions. A later anticonvulsant effect, maximal at 1 to 2 days and dissipating within a week, was manifested by less intense behavioral convulsions without change in the duration of electrical seizure activity. Both effects were dose-dependent. No change in afterdischarge thresholds was detected at any time after the administration of cysteamine. Intraventricular administration of somatostatin to animals with behavioral seizures attenuated by cysteamine treatment restored the responses to precysteamine levels. We conclude that somatostatin facilitates the spread of seizures over limbic circuits from a region of focal seizure initiation.
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PMID:Somatostatin augments the spread of limbic seizures from the hippocampus. 288 25

Cysteamine and its dimeric form cystamine have been applied to the rat striatum by local injection. Both compounds resulted in a dose-dependent decrease of somatostatin levels. Maximal reduction of somatostatin (by about 50%) was obtained at a dose of 50 micrograms of cysteamine or cystamine after about 6 h. All three molecular weight forms of somatostatin--somatostatin-14, somatostatin-28, and the 13,000 molecular weight form of somatostatin--were reduced, as shown by size exclusion HPLC. Injection of radiolabeled cystamine revealed a fast conversion of the compound to cysteamine, suggesting it is active in the monomeric form. The levels of neuropeptide Y, which is colocalized with somatostatin in striatal neurons, failed to be changed by local or intraperitoneal injection of cysteamine, suggesting that this treatment does not affect vesicles of somatostatin/neuropeptide Y neurons.
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PMID:Effect of local injection of cysteamine and cystamine on somatostatin and neuropeptide Y levels in the rat striatum. 289 23


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