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)

Parenteral somatostatin has been used to suppress growth hormone secretion in acromegalic patients, but long-term treatment is hampered by its short half-life of a few minutes in the circulation. An octapeptide analogue of somatostatin (SMS 201-995) has recently been developed that has greater potency and selectivity in suppressing growth hormone than the native hormone. In this study somatostatin and somatostatin octapeptide infusions were compared in 13 patients with active acromegaly. The octapeptide had a longer duration of action in the suppression of growth hormone than native somatostatin. A twice daily dose of 100 micrograms significantly suppressed growth hormone during the day. Prolactin was not suppressed, even in hyperprolactinaemic patients, and suppression of insulin was of short duration. Two patients had diarrhoea, but this disappeared when treatment with the octapeptide was stopped. Somatostatin is known to suppress pancreatic exocrine function, and it is therefore important to look for evidence of malabsorption during long-term treatment with the octapeptide. Somatostatin octapeptide is therefore useful in the treatment of acromegaly, but evidence of malabsorption should be watched for; nonparenteral routes of administration need to be assessed.
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PMID:Somatostatin octapeptide (SMS 201-995) in the medical treatment of acromegaly. 287 97

Prolactin (PRL) cells in the rostral pars distalis of the tilapia Oreochromis mossambicus respond to somatostatin (SRIF) and reduced medium osmotic pressure within 10-20 min of exposure during perifusion incubation. Pieces of rostral pars distalis tissue were removed from freshwater-adapted tilapia and were preincubated in [3H]leucine in static culture (355 m phi smolal) for 48 hr. Following preincubation, they were placed in the perifusion apparatus and baseline release was established for 3 hr in hyperosmotic medium (355 m phi smolal). Exposure to hyposmotic medium (280 m phi smolal) resulted in a rapid and steep rise in the release of [3H]PRL, which remained elevated for more than 2 hr. When SRIF was added simultaneously with hyposmotic medium, the rise in PRL release normally initiated by reduced osmotic pressure was prevented. Somatostatin also quickly reduced release that had been previously elevated by exposure to hyposmotic medium. The time course of these changes suggests that SRIF and altered osmotic pressure act on PRL secretion in at least partial independence of effects which they may have on PRL synthesis in the tilapia pituitary.
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PMID:Somatostatin and altered medium osmotic pressure elicit rapid changes in prolactin release from the rostral pars distalis of the tilapia, Oreochromis mossambicus, in vitro. 287 67

Changes in DNA synthesis in lactotrophs of primary monolayer cultures of the rat pituitary cells were studied, using immunoperoxidase staining in combination with autoradiography. Pituitary cell cultures were treated for 3 days with thyroliberin (TRH), bromocriptine (CB154) or somatostatin (SRIF). The proportion of lactotrophs labelled with 3H-thymidine in the total pool of labelled cells served as a criterion for the estimation of DNA synthesis in prolactin-secreting cells. Prolactin secretion by the same cultures was measured by homologous radioimmunoassay. TRH (10 ng/ml) stimulated DNA synthesis in the total population of pituitary cells, but not in lactotrophs. SRIF decreased selectively the proliferation of lactotrophs, but failed to depress or even stimulated DNA synthesis in some cell types of the rat pituitary gland in the cultures. The quantitative method of studying DNA synthesis in anterior pituitary may be used to evaluate the effects of a number of biologically active compounds on various cell systems.
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PMID:[Regulation of hormonal secretion and DNA synthesis in the lactotrophs of the rat adenohypophysis in vitro in primary cell cultures]. 289 27

Changes in hormone secretion and/or metabolism almost constantly accompany stressful events. The hormonal response to stress is directly related to the intensity of the stimulus, and greatly depends on the individual's perception of potentially stressful situations. Hypoglycaemia, surgery and exercise represent physical, metabolic and psychological stressful events where the activation of the endocrine system plays a great role. These endocrine responses also include the secretion of GH and prolactin, but the response pattern varies with the stimulus. Hypoglycaemia, exercise and surgery are potent stimuli to GH and prolactin release, both in men and women. The available data suggest that prolactin is more responsive than GH to surgical stress, whereas physical exercise and hypoglycaemia preferentially stimulate GH secretion. Prolactin levels during hypoglycaemia rise solely when symptomatic neuroglycopenia is achieved. By contrast, prolactin and GH responses to purely psychological stress are rarely seen, although some forms of reproductive stress may potentiate prolactin release in women. A teleologically satisfactory rationale for the acute GH and prolactin rise in response to these stressful stimuli is not clearly apparent in man. No definite metabolic activity of prolactin on intermediate metabolism has been demonstrated, although prolactin is mildly diabetogenic. The known metabolic actions of GH do not appear to be critical during surgery or acute hypoglycaemia, although GH probably participates in the regulation of metabolic homeostasis during chronic hypoglycaemia and chronic exercise. Changes in secretion and/or metabolism of hypothalamic neurotransmitters can increase the secretion of GH by increasing the secretion of GHRH or by decreasing the secretion of somatostatin. The prolactin rise is brought about by either a decrease in dopamine activity, an increased secretion of a hypothetical PRF, or by both mechanisms. Since multiple neuronal pathways converge on the hypothalamus from many other parts of the brain, the pronounced effects of hypoglycaemia, exercise and surgery on the secretion of GH and prolactin also reflect the action of different and complex neural inputs on the activity of the hypothalamic-pituitary axis. However, the morpho-functional mapping of these excitatory pathways still remains incomplete. TSH secretion is tightly regulated by the negative feed-back mechanism exerted by thyroid hormones. The small changes in TSH level observed during surgery and physical exercise seem to reflect mainly alterations in peripheral T4 metabolism.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Prolactin, growth hormone and thyrotropin-thyroid hormone secretion during stress states in man. 332 98

Cell suspensions derived from adult rat anterior pituitary glands were cultured for up to eight days. Prolactin immunoreactivity and/or tritiated thymidine incorporation into DNA of cell nuclei were demonstrated in cells with and without thyroliberin (TRH) and somatostatin (SRIF) treatment. It has been established that (a) TRH, which is effective in releasing both thyrotropin and prolactin, may stimulate cell proliferation in other than its target cells; that (b) SRIF has no effect on lactotropic cell proliferation and augments thymidine incorporation into DNA of unidentified cells; that (c) immunoreactive lactotropic cells with tritium-labelled nuclei are present in each culture, independent of hypothalamic hormone treatments.
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PMID:Rate of thymidine incorporation and incidence of parenchymal cell division in adult rat hypophyseal cell cultures. Effect of thyroliberin and somatostatin. 611 80

The effect of bromocriptine and somatostatin on hormone secretion and the ultrastructure of human pituitary adenomas was studied in vitro. Prolactin secretion was inhibited by bromocriptine in 3 out of 10 prolactin-secreting tumours and in explants from 2 normal pituitaries. GH secretion was reduced by bromocriptine in 4 out of 6 GH-secreting adenomas but was not affected by the drug in the incubations of normal pituitaries. Somatostatin inhibited GH secretion in 2 out of 5 pituitary adenomas and the effect was comparable with that of bromocriptine. Incubation of prolactin-secreting adenomas with oestradiol for as long as 24 days produced no change in hormone secretion. Examination of tumour explants by electron microscopy showed that somatostatin and bromocriptine produced accumulation of secretion granules but no changes in the secretory organelles. Long term bromocriptine treatment of "nude" athymic mice bearing xenografts of human pituitary adenomas suppressed hormone secretion and produced some increase in secretion granules but there were no morphological changes in the secretory organelles or other vital structures of the adenoma cells.
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PMID:Effect of bromocriptine, somatostatin, and oestradiol-17 beta on hormone secretion and ultrastructure of human pituitary tumours in vitro. 611 72

Prolactin secretion from ovine pituitary cell cultures was stimulated by thyrotropin-releasing hormone (TRH) (10(-10)-10(-7) M) with a half-maximal effect at approximately 2.5 X 10(-9) M. A maximally effective concentration of TRH produced a peak secretory response, 5-10-fold stimulation over basal release, within 15 min. Dopamine (10(-10)-10(-7) M) but not somatostatin caused a dose-related inhibition of TRH (10(-8) M) stimulated prolactin release. Both dopamine (10(-7) M) and somatostatin (10(-7) M) inhibited basal secretion from the cells. TRH did not significantly increase pituitary cell cyclic AMP levels under any of the conditions tested. Stimulation of prolactin secretion by TRH was not prevented when Ca2+ was omitted from the incubation medium. Dopamine inhibited secretion induced by TRH under low Ca2+ conditions. Our results are consistent with a hypothesis that TRH may stimulate prolactin secretion via release of intracellular Ca2+ rather than increased cellular Ca2+ uptake, and imply that dopamine inhibition involves a lowering of intracellular Ca2+ levels.
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PMID:Studies of TRH-induced prolactin secretion and its inhibition by dopamine, using ovine pituitary cells. 614 44

Pituitary glands of grassfrog (Rana pipiens), bullfrog (Rana catesbeiana), clawed toad (Xenopus laevis) and two species of terrapin (Chrysemys picta and Pseudemys scripta) were incubated in medium containing hypothalamic extract (HE), thyrotrophin releasing hormone (TRH), somatostatin, dopamine, or combinations of these treatments. Prolactin and GH concentrations in the medium were determined by densitometry after polyacrylamide-gel electrophoretic separation. Hypothalamic extract stimulated secretion of both hormones in all species tested. Thyrotrophin releasing hormone stimulated secretion of prolactin and GH, showing a biphasic pattern of response. Dopamine had little effect alone, but inhibited HE- and TRH-stimulated release of prolactin, but not GH, in both amphibia and reptiles. Somatostatin by itself had no apparent effect on release of hormones, but it inhibited HE- and TRH-stimulated release of GH from both amphibian and reptilian pituitary glands. These results indicate that factors affecting mammals and birds also interact in the regulation of secretion of prolactin and GH in lower vertebrate species.
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PMID:Effects of synthetic mammalian thyrotrophin releasing hormone, somatostatin and dopamine on the secretion of prolactin and growth hormone from amphibian and reptilian pituitary glands incubated in vitro. 614 54

Major advances in our understanding of the synthesis and release of anterior pituitary hormones have been made over the past several years. Neurons of the hypothalamus have been found to serve as "neuroendocrine transducers" in that they have both electrical and secretory functions. Peptidergic neurons respond to appropriate stimuli with a release of hypothalamic factors into the hypophyseal-portal system. These factors or hormones ultimately control the endocrine function of anterior pituitary cells. Three hormones, Thyrotropin Releasing Hormone (TRH), Gonadotropin Releasing Hormone (GnRH or LHRH) and somatostatin have been identified, synthesized and tested for clinical applications. The clinical assessment of pituitary function has been greatly improved by new and improved radioimmunoassays. One of the recent clinical advances in the area of pituitary disease has been the determination of the relatively high frequency of prolactinomas. Prolactin secreting microadenomas are an important and treatable cause of amenorrhea and infertility in young women. In addition, many pituitary tumors previously believed to be non-functional or "chromophobe adenomas" appear to be prolactinomas. Many new diagnostic and therapeutic techniques are continuing to be developed to improve our management of patients with hypothalamic-pituitary disease.
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PMID:Recent advances in the control and function of the anterior pituitary. 627 29

Polypeptide-hormone producing cells were localized in the alimentary tract and cerebral ganglion of Ciona intestinalis using cytochemical, immunocytochemical and electron-microscopical methods. Antisera to the following peptides of vertebrate type were employed: bombesin, human prolactin (hPRL), bovine pancreatic polypeptide (PP), porcine secretin, motilin, vasoactive intestinal polypeptide (VIP), beta-endorphin, leu-enkephalin, met-enkephalin, neurotensin, 5-hydroxytryptamin (5-HT), cholecystokinin (CCK), human growth (GH), ACTH, corticotropin-like intermediate lobe peptide (CLIP) and gastric inhibitory peptide (GIP). Immunoreactive cells were found both in the alimentary tract epithelium and in the cerebral ganglion for bombesin, PP, substance P, somatostatin, secretin and neurotensin. Additionally, in the cerebral ganglion only, there were cells immunoreactive for beta-endorphin, VIP, motilin and human prolactin. 5-HT positive cells, however, were restricted to the alimentary tract. No immunoreactivity was obtained either in the cerebral ganglion or in the alimentary tract with antibodies to leu-enkephalin, met-enkephalin, CCK, growth hormone, ACTH, CLIP and GIP. Prolactin-immunoreactive and pancreatic polypeptide-immunoreactive cells were argyrophilic with the Grimelius' stain and were found in neighbouring positions in the cerebral ganglion. At the ultrastructural level five differently granulated cell types were distinguished in the cerebral ganglion. Granules were present in the perikarya as well as in axons. The possible functions of the peptides as neurohormones, neuroregulators and neuromodulators are discussed.
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PMID:Gastro-intestinal and neurohormonal peptides in the alimentary tract and cerebral complex of Ciona intestinalis (Ascidiaceae). 627 5


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