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)

We investigated the effects of various hormones and growth factors on aromatase activity in cultured human skin fibroblasts. Several potential trophic factors were tested for their ability to modify basal aromatase activity or the response to dibutyryladenosine 3',5'-cyclic monophosphate and dexamethasone because (i) no endogenous ligand has been identified that is responsible for stimulating aromatase activity in the periphery, and (ii) dexamethasone and cAMP analogs can increase this enzyme's activity in fibroblasts. The effect of insulin and insulin-like growth factors were examined in closer detail because of the clinical association between insulin and hyperandrogenism. Pituitary hormones and hypothalamic releasing factors, such as human ACTH (10 nM), beta-endorphin (10 nM), beta-lipotropin (10 nM), alpha-MSH (10 nM), gamma 3-MSH (10 nM), ovine luteinizing hormone (10 ng/ml), ovine follicle-stimulating hormone (10 ng/ml), ovine thyroid-stimulating hormone (10 ng/ml), rat growth hormone (10 ng/ml), rat prolactin (10 ng/ml), rat corticotropin-releasing factor (10 nM), luteinizing hormone-releasing factor (10 nM), thyrotropin-releasing factor (10 nM), human growth hormone-releasing factor (10 nM), and somatostatin (10 nM), have no significant effects on aromatase activity. Porcine inhibin A (10 ng/ml) and porcine activin AB (10 ng/ml), two ovarian hormones with structural transforming homology to transforming growth factor-beta, also have no effect on aromatase activity. Although basic fibroblast growth factor (1-100 ng/ml), acidic fibroblast growth factor (1 ng/ml), epidermal growth factor (1 ng/ml), platelet-derived growth factor (1 ng/ml), tumor necrosis factor (1 ng/ml), and transforming growth factor-beta 1 (1 ng/ml) have no effect on basal aromatase activity in human skin fibroblasts, all of these growth factors inhibited the ability of dibutyryladenosine 3',5'-cyclic monophosphate to stimulate aromatase activity. In contrast, both insulin (100 pg/ml-10 ng/ml) and insulin-like growth factor-1 (1-100 ng/ml) had no effect on cAMP-stimulated aromatase but potentiated the action of dexamethasone (100 nM). Thus, there is a clear distinction between the effects of dexamethasone and cAMP on peripheral aromatase. On the basis of the results presented here, it is interesting to speculate that the hyperandrogenism that is often associated with insulin resistance may be due to a combination of growth factor-mediated inhibition of aromatase activity and the failure of peripheral tissues to respond to insulin and metabolize androgens to estrogens.
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PMID:Growth factor-mediated regulation of aromatase activity in human skin fibroblasts. 167 98

There is clear evidence for communication between the immune and neuroendocrine systems. However, the effect of cytokines as major immune mediators on the hypothalamic growth peptides, GHRH and somatostatin (SRIH), is not well established. To investigate a possible hypothalamic action of the cytokines interleukin-1 beta (IL-1), interleukin-6, and tumor necrosis factor-alpha, on the release of GHRH and SRIH, we used a previously validated acute rat hypothalamic explant system. IL-1 caused a pronounced dose-dependent stimulation of SRIH in the dose-range 1-100 U/ml (P less than 0.01). GHRH showed a slight, but significant, increase in response to IL-1 tested in the dose-range 10-100 U/ml. Similar studies with mediobasal hypothalamic (GHRH and SRIH) or median eminence (SRIH) fragments produced no change in either GHRH or SRIH release. The effects of IL-1 were antagonized by the cyclo-oxygenase inhibitor, indomethacin (10 micrograms/ml). Stimulation of GHRH and SRIH could not be blocked by the CRH-antagonist alpha-helical CRH (9-41) at 10(-6) M. Interleukin-6, in the dose range 10-100 U/ml, and tumor necrosis factor-alpha, in the dose range 10-10,000 U/ml, had no effect on the acute hypothalamic release of either GHRH or SRIH. It is concluded that IL-1 stimulates the acute hypothalamic release of GHRH and SRIH, and that this effect is mediated by cyclo-oxygenase products. The marked IL-1 stimulation of hypothalamic SRIH release may override the minor increase of GHRH increase, and may thus contribute to disturbances in growth seen in the presence of chronic inflammation.
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PMID:Interleukin-1 beta modulates the acute release of growth hormone-releasing hormone and somatostatin from rat hypothalamus in vitro, whereas tumor necrosis factor and interleukin-6 have no effect. 167 97

Inflammatory states are associated with nervous and neuroendocrine responses, which appear to be mediated through the actions of cytokines. Since endotoxin treatment in the rat is associated with declines in thyrotropin (TSH) secretion and growth hormone (GH) secretion, changes that may be explained by stimulation of hypothalamic somatostatin (SRIF), the effects of cytokines on SRIF were examined. In an in vitro model system consisting of fetal rat diencephalic cells interleukin-1 (IL-1), tumor necrosis factor (TNF) and interleukin-6 (IL-6) were found to stimulate the synthesis and release of SRIF. This effect developed slowly over 24 hours and was dose- and time-dependent. Acute release of SRIF over periods up to 1 hour was not found. The mechanism of cytokine stimulation of SRIF is not known. Since the depletion of glial cells in the cultures inhibits the effect, mediators that depend on the presence glia may be involved. The ability of cytokines to stimulate brain SRIF is likely to prove relevant to our understanding in many areas, including brain development, brain responses to injury, and neuroendocrine changes in chronic illness.
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PMID:Somatostatin regulation by cytokines. 197 2

Prolactin binds to lymphocytes and monocytes and can modulate immune cell function. It was postulated that proteins released from activated macrophages and lymphocytes could directly influence prolactin release and thus form an endocrine control loop during infection, tumor invasion, or inflammation. This hypothesis was tested by exposing cultured rat anterior pituitary cells to murine tumor necrosis factor-alpha (TNF-alpha) and/or interferon-gamma (IFN-gamma) for 24 h before a 4-h test of cell function. Overall prolactin accumulation during this first 24 h was inhibited by TNF-alpha and markedly reduced by TNF-alpha plus IFN-gamma. In contrast, thyroid-stimulating hormone levels were unchanged in these same media. During the subsequent 4-h challenge, both cytokines reduced thyrotropin-releasing hormone-stimulated prolactin release but had no effect on inhibited prolactin release mediated by dopamine and somatostatin receptors. Cellular viability (assessed by trypan blue and chromium release assays) and prolactin cell content were unchanged after TNF-alpha or IFN-gamma treatment. We conclude that both TNF-alpha and IFN-gamma have the potential to act directly on anterior pituitary cells to slow the rate of prolactin release.
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PMID:Tumor necrosis factor-alpha and interferon-gamma reduce prolactin release in vitro. 212 38

Cachectin (tumor necrosis factor) is a powerful macrophage hormone released during infection, which circulates in blood to produce diverse effects in the organism. We examined the effect of cachectin on release of anterior pituitary hormones from either hemipituitaries or dispersed pituitary cells incubated in vitro. The action of cachectin on dispersed cells was demonstrable only after 2 hr of incubation. With this incubation time, the protein produced a dose-related stimulation of release of adrenocorticotropin (ACTH), growth hormone (GH), and thyrotropin (TSH), but not of prolactin (Prl), from both hemipituitaries and dispersed cells. The doses required for stimulation were low in the case of hemipituitaries, usually of the order of 10(-12) M, whereas they were higher by one or two orders of magnitude with the dispersed pituitary cells. This may be related either to loss of receptors for the protein during the dispersion procedure or to the fact that in the hemipituitary system cell interactions are facilitated because the cells are close to each other. In the dispersed cell system cachectin evoked a dose-related decrease in cyclic AMP content. Incubation with somatostatin lowered the cyclic AMP content of the cells and depressed GH output without altering output of TSH or Prl. When somatostatin and cachectin were incubated together with the cells, the suppression of cyclic AMP production was abolished; TSH and Prl release were stimulated, but the action of cachectin to stimulate GH release was blocked. The stimulation of Prl release by cachectin in the presence of somatostatin may be related to the elevation of cyclic AMP, a known stimulator of Prl release. The cyclooxygenase inhibitor indomethacin nearly completely blocked the stimulatory effect of cachectin on release of GH and TSH from dispersed pituitary cells but had only a slight and nonsignificant attenuating effect on its ACTH-releasing action. These results suggest that at least part of the stimulatory action of the peptide on pituitary hormone release is brought about by prostaglandins. The failure of indomethacin to block the release of ACTH induced by cachectin suggests that other mechanisms may be involved in the release of ACTH induced by this peptide. Since the concentrations of cachectin required to stimulate pituitary hormone release are similar to those that are encountered in plasma during infection, it is likely that this direct pituitary action has pathophysiological significance.
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PMID:Cachectin alters anterior pituitary hormone release by a direct action in vitro. 256 80

We examined the chronic (72 h) effects of 30 ng/ml recombinant murine tumor necrosis factor (TNF)-alpha on release of immunoreactive growth hormone (GH), prolactin (PRL), thyrotropin (TSH), and TSH glycosylation, as assessed by lectin binding, in cultured rat anterior pituitary cells. In cultured cells from adult female rats, TNF-alpha significantly suppressed basal and GH-releasing hormone (GRH)-stimulated GH release. TNF-alpha also suppressed basal PRL release and completely abolished the PRL response to TRH (0.1-10 nM). Whereas TNF-alpha reduced basal TSH release, it significantly enhanced the maximal TSH response to TRH. TNF-alpha did not affect the concanavalin A and lentil lectin binding of TSH accumulated in the medium during the 4-day culture, but significantly decreased the lentil lectin binding of TSH released in response to acute TRH stimulation. TNF-alpha significantly enhanced the inhibitory effect of somatostatin on stimulated PRL release, but not on GH or TSH release. Compared to cell cultures from adult female rats, in anterior pituitary cell cultures from 12-day-old rats the effects of prolonged exposure to TNF-alpha on hormone release were diminished or absent. Pituitary hormone release was unaffected by acute (3 h) exposure to TNF-alpha. These results demonstrate a direct effect of TNF-alpha on anterior pituitary hormone release, which is cell-type specific and age dependent.
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PMID:Prolonged effects of tumor necrosis factor-alpha on anterior pituitary hormone release. 747 97

Glucocorticoids are potent antiinflammatory agents. They inhibit leukocyte chemotaxis and vascular permeability and generally suppress the expression of many inflammatory mediators. Recent reports suggested that somatostatin (Sms) had significant immunomodulatory properties in vitro and in vivo. In this study we examined the effects of glucocorticoids on immunoreactive somatostatin expression in aseptic inflammatory sites of Sprague-Dawley rats given carrageenin sc. The progress of the inflammatory reaction was studied over a 7-h period with respect to the volume and cellularity of the exudate and the levels of the inflammatory mediators expressed in the inflammatory site, including immunoreactive substance P (sP), corticotropin-releasing hormone (CRH), and tumor necrosis factor-alpha (TNF alpha). Dexamethasone significantly reduced the volume and cellularity of the inflammatory exudates; in parallel, the levels of immunoreactive sP, CRH, and TNF alpha were significantly suppressed by this glucocorticoid. In contrast, immunoreactive Sms was stimulated by dexamethasone in a time-dependent fashion. These findings suggest another mechanism for suppression of the inflammatory reaction by glucocorticoids via stimulation of local Sms expression, which occurs in parallel to the inhibition of the local inflammatory mediators sP, CRH, and TNF alpha.
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PMID:Somatostatin may participate in the antiinflammatory actions of glucocorticoids. 754 77

Interleukin-1, tumor necrosis factor, and interleukin-6 inhibit insulin release and may be cytotoxic to isolated pancreatic islets. These cytokines have been postulated to play an important role in the beta cell destruction characteristic of type 1 diabetes. The present study was designed to investigate the effect of the above cytokines on insulin, glucagon, somatostatin, and thyrotropin-releasing hormone secretion by isolated human islets. In addition, we have investigated if cytokine-induced modifications in hormone secretion are accompanied by modifications in the ab initio synthesis of any specific lipidic fraction. All three cytokines studied, although not modifying insulin and somatostatin release to glucose 5 mmol/L, inhibited the response of both hormones to glucose 20 mmol/L. On the other hand, the cytokines almost completely blocked islet basal glucagon release, without affecting thyrotropin-releasing hormone secretion. The added cytokines also suppressed 20 mmol/L [U-14C]glucose incorporation into both phospholipids and diacylglycerol. Our results demonstrate a beta-, alpha-, and delta-cell, sensitivity to cytokine action. Additionally, they suggest that ab initio lipid synthesis might be implicated in the mechanism of insulin release in human islets.
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PMID:Cytokine-induced inhibition of lipid synthesis and hormone secretion by isolated human islets. 802 53

Growth hormone, prolactin and somatostatin are polypeptide hormones of the neuroendocrine and peripheral nervous systems. In vitro, these have opposing effects on cells of the immune system. We compared the effects of these peptides on activation of neutrophils using a recombinant preparation of human growth hormone, human prolactin and octreotide, a long acting analog of somatostatin. In the absence of growth hormone, octreotide did not affect either neutrophil locomotion or respiratory burst. Octreotide, however, significantly antagonized growth hormone-induced activation of neutrophils for enhanced respiratory burst as well as growth hormone-induced inhibition of stimulated migration. As the effect of growth hormone on neutrophils is mediated by the prolactin receptor, its inhibition by octreotide was also tested using prolactin as priming agent. Data indicate comparable effects of octreotide on priming of neutrophils by prolactin. The effect of octreotide was dose-dependent and appeared to be selective, as activation of neutrophil respiration burst by gamma-interferon, and inhibition of stimulated migration by tumor necrosis factor-alpha were unaffected by octreotide. The present study suggests that octreotide may act on neutrophils directly by antagonizing growth hormone or prolactin at the cellular level.
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PMID:Inhibition of recombinant human growth hormone-induced and prolactin-induced activation of neutrophils by octreotide. 809 70

It is well established that IL-1 beta acts in the brain to potently inhibit gastric acid secretion in pylorus-ligated rats. The present study was designed to further investigate the specificity and mechanisms of the centrally mediated antisecretory action of IL-1 beta in conscious rats. Intracerebroventricular injection of IL-1 beta (100 ng) decreased acid secretion in pylorus-ligated rats and inhibited basal and pentagastrin-stimulated acid secretion in rats with chronic gastric fistula. The antisecretory effect of IL-1 beta (100 ng) injected into the lateral ventricle of pylorus ligated rats was completely reversed by prior intracerebroventricular injection of the IL-1 receptor antagonist, IL-1ra, (100 micrograms). Peripheral administration of the somatostatin monoclonal antibody, CURE.S6, did not modify intracisternal IL-1 beta-induced inhibition of acid secretion in pylorus ligated rats. IL-6 and tumor necrosis factor-alpha (100 ng) injected intracisternally did not influence gastric acid secretion in pylorus-ligated rats. These data show that IL-1 beta action in the CNS is mediated through interaction with specific IL-1 receptors and is selective to this cytokine. IL-1 beta antisecretory action can be observed under basal and pentagastrin-stimulated conditions and is independent from somatostatin release in the periphery.
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PMID:Central interleukin-1 beta-induced inhibition of acid secretion in rats: specificity of action. 843 8


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