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)

In normal subjects somatostatin cannot modify the plasma levels of prolactin when they are in a normal range or when they are pharmacologically increased. In the case of pituitary adenoma (prolactinic or eosinophilic), the response of prolactin to somatostatin varies widely. In some patients there is a marked decrease of the prolactin levels while in others no modification is observed.
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PMID:[Effects of somatostatin upon prolactin secretion both in normal subjects and in patients presenting pituitary adenoma (author's transl)]. 4 79

We evaluated serum alpha-subunit concentrations in 72 patients bearing pituitary adenomas. We conclude that: 1) alpha-subunit hypersecretion is found in all patients with TSH secreting pituitary adenoma (n = 10). Two patients have a predominant secretion of alpha-subunit as compared to TSH secretion. 2) As concerns gonadotropin secreting pituitary adenomas (n = 3), all patient have elevated serum alpha-subunit levels with increased FSH and LT concentrations in 2 cases and 1 case respectively. 3) In prolactinomas (n = 14), alpha-subunit concentrations are not significantly different from that of normal subjects. 4) In 11 acromegalic patients, alpha-subunit hypersecretion is found in 2 patients only with GH-alpha and GH-PRL-alpha secreting pituitary adenomas. 5) Among 34 patients with nonsecreting adenomas, 8 have elevated alpha-subunit concentrations (24%). Positive immunocytochemical staining is found in 70% most often with gonadotropins (55%). Only a few pituitary tumors with positive alpha-subunit immunocytochemical staining have elevated serum alpha-subunit levels. At least, the measurement of basal circulating alpha-subunit levels is very useful in the follow-up of patients with nonsecreting adenomas. In our study, medical treatments including bromocriptine and somatostatin analogues have been found effective in patients with alpha-subunit hypersecretion. Further investigations are necessary to prove if such treatments could control tumoral growth and could prevent recurrences.
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PMID:[Value of alpha subunit assay in pituitary pathology]. 128 29

Thyroliberin (TRH), vasoactive intestinal peptide (VIP) and somatostatin (SRIF) act through receptors that are coupled to guanine nucleotide-binding regulatory proteins (G proteins). Regulation of hormone action may occur at the level of G protein coupling to the receptor or effector systems. In this study we demonstrate that prolonged exposure (for up to 48 hr) of cultured rat pituitary adenoma GH3 cells to these hormones caused homologous and to some extent heterologous attenuation of the adenylyl cyclase (AC) (EC 4.6.1.1) responsiveness. In addition, TRH and SRIF diminished both TRH- and guanosine 5'-[beta gamma-imido]-triphosphate-enhanced phospholipase C (PLC) (EC 3.1.4.3) activity within the same time-course. Measurements of cells membrane levels of Gs protein alpha-subunit (Gs alpha), G(i)-1 alpha/G(i)-2 alpha, G(i)-3 alpha, G(o) alpha and G beta by immunoblotting were performed. TRH and VIP upregulated levels of all G proteins except G(o) alpha and G beta. In contrast, SRIF caused a marked reduction of G beta levels. Thus, TRH and VIP, both acting through Gs, both modulated the alpha-subunit levels of this signal transducer, whereas SRIF, which possibly acts through G(i)-2, did not change the steady state level of G(i)-2 alpha. The actions of TRH, VIP and SRIF are multifaceted at the G protein level, where modulations of subtypes not directly involved in their actions may occur. These findings emphasize the complexity expected to be found in the in vivo situation.
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PMID:Hypothalamic hormones modulate G protein levels and second messenger responsiveness in GH3 rat pituitary tumour cells. 135 62

We have investigated the modulation of different G protein alpha- and beta-subunit levels in prolactin (PRL) and growth hormone producing rat pituitary adenoma cells (GH3 cells) in culture after prolonged exposure (6-48 h) to the steroid hormones 17 beta-oestradiol and dexamethasone. Gi-3 alpha- and G beta-subunits were the only G protein subunits which increased in response to 10(-6) M oestradiol (to approximately 150 and 200% of controls, respectively), while the other alpha-subunits investigated (Gs alpha, Gi-2 alpha and G(o) alpha) remained relatively unchanged. Thyroliberin (TRH)--and guanosine 5'-[beta gamma-imido]trisphosphate (Gpp(NH)p)-elicited adenylyl cyclase (AC) activities were reduced during 6-12 h of oestradiol treatment (by 60 and 20%, respectively), while the inhibitory effect of somatostatin (SRIF) increased by approximately 100%. Dexamethasone (10(-6) M) increased levels of the stimulatory G protein Gs alpha (to approximately 340%) and decreased levels of Gi-3 alpha (to 25%). After 48 h, the AC response to TRH was reduced by approximately 70%, whereas the effect of the other modulators remained close to controls. We conclude that G protein subunits in GH3 cells are subject to specific regulation by steroid hormones and that this may be important in the tuning of the responsiveness of PRL secretion to hormones in the in vivo situation.
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PMID:Modulation of G proteins and second messenger responsiveness by steroid hormones in GH3 rat pituitary tumour cells. 136 54

A 35-yr-old woman is described as having atypical McCune-Albright syndrome, associated with acromegaly and hyperprolactinemia due to pituitary adenoma. The patient did not present sexual precocity, but primary amenorrhea. After transphenoidal adenomectomy, the GH plasma levels returned to normal, whereas the PRL values decreased; bromocriptine therapy normalized PRL levels and induced ovulatory menses. After 4 uneventful yr the patient developed relapse of active acromegaly that did not recover after a second neurosurgical exploration. Bromocriptine treatment maintained normal PRL levels but did not significantly reduce GH ones; the association with long-acting somatostatin analog SMS 201-995 by continuous sc pump infusion induced definitive control of GH and somatomedin-C secretion. These results suggest an additive inhibitory effect on GH secretion exerted by the two drugs.
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PMID:Atypical McCune-Albright syndrome associated with growth hormone-prolactin pituitary adenoma: natural history, long-term follow-up, and SMS 201-995--bromocriptine combined treatment results. 140 Aug 88

The McCune-Albright syndrome, comprising polyostotic fibrous dysplasia, cutaneous pigmentation and endocrine hyperfunction, is occasionally complicated by acromegaly due to a pituitary adenoma. We report a patient with the McCune-Albright syndrome and acromegaly, who developed secondary hypothyroidism and hypoadrenalism, in whom surgical removal of the pituitary tumour was technically difficult. A combination of a long-acting somatostatin analogue ('Sandostatin') and external irradiation were therefore used as treatment.
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PMID:Acromegaly and its treatment in the McCune-Albright syndrome. 142 86

We have studied seven patients with a clinically nonfunctioning or alpha-subunit-secreting pituitary macroadenoma, four of whom received long term, high dose octreotide treatment. We have attempted to correlate the presence of somatostatin receptors (SS-R) in the adenomas and the outcome of octreotide treatment, as measured by tumor size, improvements in visual field defects, and hormonal response. The presence of SS-R in the pituitary adenomas was demonstrated in vivo using [111indium]octreotide scintigraphy and in vitro by autoradiography of tissue fragments obtained after transsphenoidal surgery. Adenomas from six of the seven subjects were SS-R positive. High dose (1200 micrograms, sc, daily) octreotide treatment was given to four subjects, three of whom were SS-R positive. Improvement of the visual field defects was observed in three of four patients (including the SS-R-negative subject), although no computed tomographic scan-assessed tumor size reduction was found. Two of four patients showed small but significant reductions in serum FSH concentrations (to 83% and 93% of initial values) with treatment. These in vivo responses to high dose octreotide treatment could not be predicted by pretreatment responses to 200 micrograms TRH or 100 micrograms octreotide. Tissue fragments for cell culture were obtained from six patients, and in vitro release of gonadotropins and/or alpha-subunit could be demonstrated in five cultures. In vitro, octreotide (10 nmol/L) significantly decreased gonadotropiin or subunit release in three of five cultures, whereas bromocriptine (10 nmol/L) significantly reduced the release in four of five cultures and to a significantly greater extent than octreotide. In conclusion, in six of seven patients with a clinically nonfunctioning or alpha-subunit-secreting pituitary adenoma, SS-R were demonstrated in the tumor. In vitro incubation of adenoma cells with octreotide resulted in mild inhibition of gonadotropin or alpha-subunit release. Although in vivo long term treatment with high doses of octreotide did not result in substantial tumor size reduction, improvement of visual field defects was observed in three of four subjects.
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PMID:Clinically nonfunctioning pituitary adenoma and octreotide response to long term high dose treatment, and studies in vitro. 143 93

The effects of bromocriptine (BC), a somatostatin analog (SMS), and heat on the secretion of growth hormone (GH) and prolactin (PRL), and on the morphologic features of human GH-secreting pituitary adenoma were studied in vitro. The treatment with BC, SMS, or heat (41.5 degrees C and 42.5 degrees C) markedly suppressed the secretion of GH and PRL from the adenoma cells and reduced the number of cells immunoreactive with GH or PRL. The combined treatment with BC and heat induced a marked reduction in the number of GH and PRL cells consistent with the effect on the secretion of GH and PRL. These results suggest that BC, SMS, and heat treatments produced the cytotoxic effects on pituitary adenoma cells, and that the simultaneous treatment of BC and heat enhanced this effect.
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PMID:Cytocidal effects of bromocriptine, somatostatin analog, and heat on growth hormone-secreting pituitary adenoma in vitro. 157 99

Acromegaly is a unique condition characterized by chronic growth hormone (GH) and insulin-like growth factor-1 (IGF-1) hypersecretion usually due to a pituitary adenoma. Rarely, acromegaly can result from a GH-releasing hormone carcinoid or pancreatic neoplasm which stimulates the normal pituitary to secrete GH. This review describes the interactions between acromegaly and the gastrointestinal system. In contrast to the soft tissue and skeletal changes, clinical organomegaly of the liver, kidney, and spleen is unusual in patients with acromegaly and should warrant further investigations. The prevalence of cholelithiasis is notably increased by the use of the otherwise effective GH-lowering somatostatin analog, octreotide. Patients on long-term therapy with this agent may require anticholelithogenic treatment. The frequency of malignant and premalignant polyps of the colon justify the routine screening for these lesions in newly diagnosed patients with acromegaly.
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PMID:Hepatobiliary and gastrointestinal manifestations of acromegaly. 161 13

Previous studies have demonstrated that normal and tumoral pituitaries release in vitro somatostatin (SRIH) and contain messenger RNAs encoding the preproSRIH. In the present study, we document the presence and characterization of the SRIH precursor in a growth hormone (GH)-secreting human pituitary adenoma, using two biochemical procedures: Sephadex G50 filtration and high performance liquid chromatography (HPLC). Sephadex G50 filtration of a 2M acetic acid extract demonstrated the presence of three SRIH-like immunoreactive (SLI) peaks, distinct from SRIH 1-28 and SRIH 1-14 used as standard. Molecular mass of the SLI material present in each peak was estimated as 21, 17 and 12 kilodaltons (kDa). SRIH 1-28 and/or 1-14 were not detected in this extract. Reverse phase HPLC was performed on a C18 column; all the three forms of SLI material coeluted with the rat hypothalamic proSRIH indicating a high homology between the human pituitary proSRIH and that of the rat hypothalamus. These results demonstrate for the first time the presence of high molecular mass proSRIH forms in a GH-secreting pituitary adenoma, and thus enable us to conclude for a local pituitary production of SRIH.
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PMID:[Presence and characterization of somatostatin precursor in human growth hormone secreting pituitary gland tumor]. 167 49


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