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 study compared inhibitory actions of transforming growth factor-alpha (TGF alpha) and epidermal growth factor (EGF) on gastric acid secretion and effects of these peptides on release of gut peptides considered important for acid inhibitory and gastrointestinal protective mechanisms. TGF alpha and EGF did not affect basal acid secretion, but inhibited pentagastrin-stimulated acid secretion in a dose-dependent manner from 0.10 to 1.7 nmol kg-1 h-1 i.v. by maximally 72% for TGF alpha (P < 0.001) and 76% for EGF (P < 0.001). At the highest doses, TGF alpha and EGF caused 194% and 698% increase of somatostatin-like immunoreactivity (SOM-LI) in plasma, respectively (each P < 0.05). Neurotensin-like immunoreactivity (NT-LI) increased 438% by EGF (P < 0.05), but the increase of 700% with TGF alpha did not reach statistical significance. The levels of vasoactive intestinal peptide-like immunoreactivity (VIP-LI) did not change. In gastric juice, SOM-LI increased 80% by TGF alpha i.v. (P < 0.05), but NT- and VIP-LI did not change. EGF i.v. had no effects on levels of SOM-, NT- or VIP-LI in luminal juice. Thus, TGF alpha and EGF inhibit acid secretion, but also promote the release of SOM and NT into the circulation and may be involved in the acid inhibitory effects of these growth factors.
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PMID:Transforming growth factor-alpha and epidermal growth factor inhibit gastric acid secretion and stimulate release of somatostatin and neurotensin in the conscious rat. 797 34

Peptides such as somatostatin (SS14), epidermal growth factor (EGF), transforming growth factor-alpha (TGF alpha), and insulin-like growth factors (IGF-I and IGF-II) are present in breast milk from various species, and their significance in the developing gastrointestinal tract has been suggested. Our recent studies have indicated that rat milk soluble fraction (RMSF) protects SS14 in the gastrointestinal lumen by inhibiting in vitro the luminal peptidolysis. In the present studies, we have shown that RMSF inhibited in vitro degradation by midjejunal luminal flushings of suckling rats of 125I-labeled somatostatin 14[Tyr11], EGF, TGF alpha, IGF-I and IGF-II, as well as trypsin activity in vitro against benzoyl-L-arginyl-p-nitroanilide. The inhibitory factors present in the RMSF were further fractionated by gel filtration on Sephadex G100, ion-exchange chromatography on DEAE-Sephadex, and fast protein liquid chromatography (FPLC). Gel filtration of Sephadex G100 separated RMSF into three peaks of proteins: G1, G2, and G3; peptidase inhibitor activities were present exclusively in G1. Ion-exchange chromatography on DEAE-Sephadex column resolved peptidase inhibitory activity (G1) into three different peaks, D1, D2, and D3, eluted at sodium chloride concentrations of 0.05 M, 0.1 M, and 0.2 M, respectively. Further purification of D2 by FPLC resulted in a fraction rich in peptidase inhibitory activity, which was essentially free of trypsin inhibitory activity. Results indicate the presence of at least three peptidase inhibitors in rat milk, which may play a role in the protection of milk-borne peptides in the gastrointestinal lumen.
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PMID:Presence of multiple forms of peptidase inhibitors in rat milk. 814 98

Of the two known forms of intestinal somatostatin, somatostatin-28 (S28) and S14, S28 predominates in the distal mucosa, whereas S14 is localized in the foregut. Although S14 release has been well studied, little is known about the factors regulating secretion of S28 from the intestine. Therefore, fetal rat intestinal cultures, which have been previously demonstrated to synthesize and secrete predominantly S28, were treated with potential nutrient, neuromodulator/transmitter, and peptide secretagogues (n = 4-6/experiment). Oleic acid dose dependently stimulated the release of somatostatin-like immunoreactivity (SLI) to 272 +/- 81% of the control value at 1.5 x 10(-4) M (P < 0.01). Gel permeation analysis (n = 3) demonstrated that this increment was accounted for not only by an increase in the release of S28, but also by an increase in that of S14, such that the secretion of both peptides was increased in parallel. Of the neuromodulators tested, only the enteric peptide gastrin-releasing peptide stimulated intestinal SLI secretion, to 386 +/- 60% of the control value at 10(-6) M (P < 0.001); similar to oleic acid, the effects on S28 and S14 were equivalent. Galanin, vasoactive intestinal peptide, bethanechol, and epinephrine did not affect SLI release. The duodenal hormone secretin also stimulated SLI release to 310 +/- 78% of the control value at 10(-6) M (P < 0.001); however, secretin caused a preferential release of S14 over that of S28 (S14, 7.8 +/- 2.8-fold; S28, 1.5 +/- 0.1-fold). In contrast, gastrin, cholecystokinin, glucose-dependent insulinotropic peptide, neurotensin, peptide YY, epidermal growth factor, and transforming growth factor-alpha had no effect on intestinal SLI release. Thus, luminal nutrients and neuro/endocrine peptides exert differential effects on S28 release from the rat intestine compared with those on S14. These findings implicate S28 as a distinct regulatory peptide in the physiological setting.
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PMID:Nutrient and peptide regulation of somatostatin-28 secretion from intestinal cultures. 942 9

Gastrin is synthesized and secreted mostly in a heptadecapeptide form from neurocrine G cells located in the antrum. The biologically active sequence of the molecule is a C-terminal pentapeptide, which has been conserved across many species. Transcriptional regulation of gastrin mRNA synthesis is positively regulated by transforming growth factor-alpha (TGF-alpha) and inhibited by somatostatin (SST). The inactive precursor form is converted to the active molecule by several post-translation processing steps which include cleavage, C-terminal amidation, glycosylation, phosphorylation and sulfation. Aberrations in processing steps generate incompletely processed forms, particularly glycosylated progastrin, which may act as autocrine growth factors for gastrointestinal neoplasms. Gastrin release is stimulated by luminal aromatic amino acids and inhibited by a decrease in luminal pH. Other gastrin agonists include beta-adrenergic agents, acetylcholine, gastrin-releasing peptide (bombesin), TGF-alpha, and possibly the gastric pathogen, Helicobacter pylori. The principal peptide inhibitor of gastrin release is SST. The major physiological roles of gastrin include stimulation of acid secretion, regulation of mucosal cell lineage and mucosal cell proliferation. The fundic enterochromaffin-like (ECL) cell is the principal cellular transducer of the gastrin-acid signal. Activation of its gastrin/CCKB receptor results in histamine synthesis and release with consequent activation of the fundic parietal cell H2 receptor. An increase in luminal pH caused by acid inhibitory pharmacotherapy agents (particularly proton pump inhibitors) results in hypergastrinemia and ECL cell hyperplasia. Gastric carcinoids however appear occur in patients with multiple endocrine neoplasia type I syndrome, suggesting that an associated genomic defect is necessary. Gastrin is thus both a potent gastrointestinal trophic and histamine secretory agent. As a hormone it is a paradigm in the elucidation of both cellular secretory and growth factor induced cell proliferation.
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PMID:Gastrin and the enterochromaffin-like cell: an acid update. 984 87

Previously, we have observed that epidermal growth factor (EGF), a potent mitogen for cultured hepatocytes, stimulates the production of IGF-I and IGF-binding proteins (IGFBPs) by cultured hepatocytes from adult rats. This study was undertaken to investigate the possibility that other growth factors of hepatic origin could specifically be involved in the regulation of IGF-I and IGFBP expression. The effects of transforming growth factor-alpha (TGF-alpha), through EGF receptors to induce a mitogenic response, and transforming growth factor-beta1 (TGF-beta1), produced by non-parenchymal liver cells and able to inhibit hepatocyte proliferation in vivo and in culture, have been studied in cultured adult rat hepatocytes. Our results demonstrate that TGF-alpha and TGF-beta1 significantly stimulate IGF-I and IGFBP secretion by cultured hepatocytes but no change in the abundance of IGF-I and IGFBP mRNAs was observed with respect to controls. Cycloheximide is able to inhibit both basal and TGF-stimulated release of IGF-I and a similar effect was elicited by octreotide, the somatostatin analog, known to directly affect hepatic IGF-I gene expression. Our findings show the role of the liver in the secretion of IGF-I and IGFBPs, not only under endocrine and nutritional control but also under autocrine and paracrine control.
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PMID:IGF-I production by adult rat hepatocytes is stimulated by transforming growth factor-alpha and transforming growth factor-beta1. 1036 13

We investigated the mechanisms of transforming growth factor-beta1 (TGF-beta1) inhibition on transforming growth factor-alpha (TGF-alpha)-induced DNA synthesis and proliferation in primary cultures of adult rat hepatocytes. TGF-alpha (1.0 ng/ml) produced a 4.2-fold elevation of DNA synthesis during 3 h of culture and a 1. 2-fold increase in nucleus number (proliferation) during 4 h of culture. TGF-beta1 dose dependently inhibited the TGF-alpha-induced hepatocyte DNA synthesis and proliferation: half-maximal inhibition occurred at a TGF-beta1 concentration of 0.08 ng/ml. The inhibitory effects of 1.0 ng/ml TGF-beta1 were almost completely reversed by adenylate cyclase inhibitors, 2,4-dideoxyadenosine (10(-6) M), and somatostatin (3 x 10(-7) M), or by a specific inhibitor of protein kinase A, H-89 (N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride; 10(-7) M). In addition, while TGF-alpha did not affect the basal cellular adenosine 3',5'-monophosphate (cAMP) levels, TGF-beta1 was found to produce dose-dependent increases in cellular cAMP levels. The cAMP-elevating effects of TGF-beta1 were also reversed by 2,4-dideoxyadenosine (10(-6) M), and somatostatin (3 x 10(-7) M), but not by H-89 (10(-7) M). The present results suggest that the specific mechanisms involved in the growth inhibitory effect of TGF-beta1 on TGF-alpha-induced hepatocyte DNA synthesis and proliferation are via stimulation of adenylate cyclase, which increases intracellular cAMP and subsequently activates protein kinase A.
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PMID:Transforming growth factor-beta1 inhibits the growth of primary adult rat hepatocyte cultures by increasing cAMP levels. 1061 79

Angiogenesis, the formation of a new blood supply, is an essential step in tumorigenesis. Although vascular endothelial growth factor (VEGF) is known to be a very potent angiogenic factor in most solid tumors, little is known about its production and regulation in pituitary adenomas. We have investigated basal and stimulated VEGF production by rodent pituitary tumor cells (mouse corticotrope AtT20, rat lactosomatotrope GH3, mouse gonadotrope alpha T3-1 and mouse folliculostellate TtT/GF cells), and by hormone-inactive (27), corticotrope (9), lactotrope (3) and somatotrope (21) human pituitary adenoma cell cultures. All 4 pituitary cell lines secreted VEGF, which in the case of AtT20, GH3 and TtT/GF cells was inhibited by approximately 50% by dexamethasone. TtT/GF cells were the most responsive to the different stimuli used since basal values were augmented by pituitary adenylate cyclase activating polypeptide-38 (PACAP-38), interleukin-6 (IL-6), transforming growth factor-alpha (TGF-alpha), IGF-I and the somatostatin analogue ocreotide. However, in GH3, AtT20 and alpha T3-1 cells, basal VEGF levels where not enhanced with any of the stimuli tested. The majority of the human adenomas tested (92%) basally secreted measurable VEGF which was inhibited by dexamethasone in most cases (84%). VEGF levels were increased in hormone inactive adenomas, somatotrope tumors and prolactinomas by TGF-alpha, PACAP-38, and 17 beta-estradiol, respectively. In conclusion, pituitary tumor cells are capable of producing VEGF which may be involved in tumoral angiogenesis. Our results concerning the suppression of VEGF by dexamethasone suggest that glucocorticoids may have anti-angiogenic properties and therefore therapeutic relevance for the treatment of pituitary adenomas.
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PMID:Vascular endothelial growth factor production and regulation in rodent and human pituitary tumor cells in vitro. 1147 17

Carcinoid tumors are rare neoplasms which, by tradition, have been divided into foregut, midgut, and hindgut tumors. Although they share many features, they seem to have different molecular backgrounds. Foregut tumors very often show involvement of the MEN1 gene with deletions and mutations, whereas midgut carcinoids display genetic changes on chromosome 18. Hindgut tumors in general show rather low proliferation capacity, and transforming growth factor-alpha/epidermal growth factor receptor autocrine mechanism may play a role in the tumor development. Sometimes it might be a problem to delineate the location of the primary carcinoid tumor, but analyzing thyroid transcription factor-1 can be of help, because this factor is only expressed in foregut carcinoid and not in midgut or hindgut tumors. Chromogranin A is an important general tumor marker for all types of carcinoid tumors. Somatostatin receptor scintigraphy is a cornerstone in staging and localization of carcinoid tumors, but newer techniques such as positron emission tomography will challenge its position in the future. Although surgical cure is not obtainable, a more aggressive surgery has emerged during the last decade. Debulking and other cytoreductive procedures are quite common today. Somatostatin analogues have been the treatment of choice in symptomatic patients with carcinoid tumors, but more recent studies have indicated a cytostatic effect of somatostatin analogues. Tumor-targeted radioactive treatment based on somatostatin analogues is now under clinical evaluation. Preliminary data indicate interesting clinical potentials.
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PMID:Carcinoid tumors: molecular genetics, tumor biology, and update of diagnosis and treatment. 1179 Sep 79

Menetrier's disease is a rare acquired disorder of the fundus and body of the stomach (ie, oxyntic mucosa) characterized by giant hyperplastic folds, protein-losing gastropathy, hypoalbuminemia, increased mucus secretion, and hypochlorhydria. Recent research implicates overproduction of transforming growth factor-alpha with increased signaling of the epidermal growth factor receptor (EGFR) in the pathogenesis. Activation of the EGFR, a transmembrane receptor with tyrosine kinase activity, triggers a cascade of downstream, intracellular signaling pathways that leads to expansion of the proliferative compartment within the isthmus of the oxyntic gland. The diagnosis of Menetrier's disease is based upon characteristic histologic changes, including foveolar hyperplasia, cystic dilation of pits, and reduced numbers of parietal and chief cells. The best treatment for Menetrier's disease is not clear. It seems reasonable to test and treat for cytomegalovirus and Helicobacter pylori, as 1) in children, evidence exists that the disease may be due to cytomegalovirus infection in up to one third of patients; and 2) in adults, there are anecdotal reports of resolution upon H. pylori eradication. More recently, therapies targeting increased signaling of the EGFR have shown promise, including somatostatin analogues and monoclonal antibodies (eg, cetuximab) directed against the EGFR. In refractory cases, gastrectomy is curative.
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PMID:Menetrier's Disease. 1832 37

The aim of the present study is to provide a review of the expression and action of trophic factors in the carotid body. In glomic type I cells, the following factors have been identified: brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, artemin, ciliary neurotrophic factor, insulin-like growth factors-I and -II, basic fibroblast growth factor, epidermal growth factor, transforming growth factor-alpha and -beta1, interleukin-1beta and -6, tumour necrosis factor-alpha, vascular endothelial growth factor, and endothelin-1 (ET-1). Growth factor receptors in the above cells include p75LNGFR, TrkA, TrkB, RET, GDNF family receptors alpha1-3, gp130, IL-6Ralpha, EGFR, FGFR1, IL1-RI, TNF-RI, VEGFR-1 and -2, ETA and ETB receptors, and PDGFR-alpha. Differential local expression of growth factors and corresponding receptors plays a role in pre- and postnatal development of the carotid body. Their local actions contribute toward producing the morphologic and molecular changes associated with chronic hypoxia and/or hypertension, such as cellular hyperplasia, extracellular matrix expansion, changes in channel densities, and neurotransmitter patterns. Neurotrophic factor production is also considered to play a key role in the therapeutic effects of intracerebral carotid body grafts in Parkinson's disease. Future research should also focus on trophic actions on carotid body type I cells by peptide neuromodulators, which are known to be present in the carotid body and to show trophic effects on other cell populations, that is, angiotensin II, adrenomedullin, bombesin, calcitonin, calcitonin gene-related peptide, cholecystokinin, erythropoietin, galanin, opioids, pituitary adenylate cyclase-activating polypeptide, atrial natriuretic peptide, somatostatin, tachykinins, neuropeptide Y, neurotensin, and vasoactive intestinal peptide.
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PMID:Trophic factors in the carotid body. 1877 56


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