Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 effects of various neurogenic peptides and neurotransmitter substances on the release of ACTH induced by hypothalamic corticotropin releasing factor (HY-CRF) were investigated using monolayer cultured anterior pituitary cells. Test substances were given in combination with 0.05-0.1 hypothalamic extract (HE)/ml, because HE evoked a significant ACTH release and a linear dose response relationship was demonstrated sequentially between 0.0165 HE/ml and 0.5 HE/ml. Relative high doses of lysine-vasopressin showed a slight additive effect on the release of ACTH induced by 0.1 HE/ml. Leu-enkephalin, dopamine, prostaglandin E1 and E2 slightly reduced the release of ACTH induced by HY-CRF, but the inhibitory effect of these substances were not dose-related. Other tested substances including luteinizing hormone releasing hormone, thyrotropin releasing hormone, somatostatin, melanocyte stimulating hormone release inhibiting factor, beta-endorphin, neurotensin, substance P, vasoactive intestinal polypeptide, angiotensin II, norepinephrine, serotonin, acetylcholine, histamine and gamma-amino butyric acid showed neither agonistic nor antagonistic effect on the release of ACTH induced by HY-CRF. These results indicate that the release of ACTH is controlled specifically by HY-CRF and corticosterone, and modified slightly by some other substances such as vasopressin and prostaglandins, and that the effect of most other neurogenic peptides and neurotransmitter substances is negligible or non-physiological at the pituitary level.
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PMID:ACTH release in pituitary cell cultures. Effect of neurogenic peptides and neurotransmitter substances on ACTH release induced by hypothalamic corticotropin releasing factor (CRF). 3 43

Biologically active peptides and neurotransmitter substances were added to anterior pituitary cell cultures to examine the presence of corticotropin releasing factor (CRF)-like activity. Hypothalamic extract (HE) induced significant dose-related increase of ACTH, and the lowest effective dose was 0.01 HE/ml. Other tested substances including luteinizing hormone-releasing hormone, thyrotropin releasing hormone, melanocyte stimulating hormone release inhibiting factor, somatostatin, substance P, neurotensin, beta-endorphin. leu-enkephalin, met-enkephalin, bradykinin, norepinephrine, dopamine, serotonin, acetylcholine, histamine, gamma-amino butyric acid or gamma-hydroxy butyric acid showed no CRF-like activity. Relatively high doses of lysine vasopressin, arginine vasopressin and angiotensin II increased the release of ACTH in pituitary cell cultures, but the maximal ACTH response was markedly less than with HE. These results indicate that cultured anterior pituitary cells are sensitive and fairly specific in detecting CRF(s) comparing with other detecting procedures.
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PMID:Specificity of cultured anterior pituitary cells in detecting corticotropin releasing factor(s): the effect of biologically active peptides and neurotransmitter substances on ACTH release in pituitary cell cultures. 3 34

Intraventricular injection of arginine-8-vasopressin and its analogues vasotocin and lysine-8-vasopressin into rat brain evoked a special rotational behavior resembling somatostatin-induced barrel rotation [1]. Oxytocin and oxypressin were less active while vasopressin fragments had no effect. Vasopressin-induced barrel rotation was accompanied by pathological symptoms indicating a disturbance of muscle tone regulation and is considered to be a non-specific and toxic effect. This rotational behavior was not prevented by atropine, propranolol, phentolamine, methylsergide or haloperidol but was reduced by chlorpromazine, probably due to the latter's muscle relaxing activity.
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PMID:Barrel rotation induced by vasopressin and related peptides in rats. 56 83

Seven synthetic analogues of somatostatin helped clarify structural requirements for suppression of growth hormone secretion in rats. Size of the ring is not critical; deletions of serine-13, lysine-4 or asparagine-5 result in peptides which retain an appreciable fraction of the activity. The analogue des-Ala1, Gly2, Asn5-somatostatin lowers plasma growth hormone and insulin levels without affecting plasma glucagon levels significantly.
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PMID:Structure activity studies on somatostatin. 105 80

Epidermal growth factor (EGF), phorbol esters (PEs), and retinoic acid (RA) inhibit differentiated functions of thyrocytes. In the present study the inhibitory effects of these growth-promoting factors on hormone synthesis were studied in thyroid follicles cultured in type-I collagen gel, and morphologic alteration by these factors was examined by light and electron microscopy (EM). Porcine open thyroid follicles obtained by treatment with 0.1% collagenase were embedded in collagen gel and cultured in Ham's F12 medium supplemented with 6H (insulin, hydrocortisone, somatostatin, transferrin, glycyl-his-lys, and thyrotropin) + 0.5% fetal bovine serum (FBS). After 1 week these open follicles developed to closed follicles, and the medium was changed to one containing 6H + 0.5% FBS + 0.1 microM sodium iodide (NaI). Some media were supplemented with either EGF, phorbol 12-myristate 13-acetate (PMA), or all-trans RA. The closed follicles retained ability for hormone synthesis for 2 weeks after the medium change in the presence of 6H + FBS + NaI. The amounts of T4 and T3 secreted into the culture medium from day 9 to day 12 after the medium change were 60% and 45% of those from day 0 to day 4, respectively. EGF reduced production of T4 and T3 by 61% and 69%, respectively; PMA, by 87% and 99%; and RA, by 55% and 44%. In the medium supplemented with 6H + 0.5% FBS, the follicles exhibited intact polarity. Apical surfaces with microvilli were oriented to the follicular lumen and tight junctions were on the apical side of cell-to-cell contacts. Desmosomes were found on both the apical and basal halves of the cell contacts.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of epidermal growth factor, phorbol ester, and retinoic acid on hormone synthesis and morphology in porcine thyroid follicles cultured in collagen gel. 149 78

We have studied the chronic effects of TSH (100 microU/ml) and insulin (10 micrograms/ml) on intracellular pH (pH(i)) in FRTL-5 cells using the pH sensitive probe 2'7-bis (2-carboxyethyl-5'-6') carboxyfluorescein. FRTL-5 cells were cultured on Petri dishes either in the presence of 4H, ie. Coons F-12 containing cortisol (10 nM), transferrin (0.5 microgram/ml), glycyl-histidyl lysine acetate (10 ng/ml) and somatostatin (10 micrograms/ml), or with 4H + insulin (5H), 4H + TSH, or 4H + TSH + insulin (6H). pH(i) was measured in small groups of cells by microspectrofluorimetry both in the presence and absence of bicarbonate ions after cells had been deprived of serum for at least a day. In the absence of TSH, insulin and bicarbonate ions, pH(i) was 7.26 +/- 0.18 (mean +/- SD, n = 49) rising to 7.89 +/- 0.09 (n = 59) and 7.43 +/- 0.1 (n = 55) in the presence of TSH (4H + TSH) and insulin (5H) respectively. Addition of both insulin and TSH (6H) resulted in a pH(i) of 7.75 +/- 0.09 (n = 40). In the absence of TSH and insulin, but the presence of bicarbonate ions, pH(i) was 7.29 +/- 0.12 (mean +/- SD n = 47) rising to 7.72 +/- 0.07 (n = 59) in 4H + TSH and 7.48 +/- 0.08 (n = 60) in 5H. pH(i) in the presence of both TSH and insulin was 7.81 +/- 0.03 (n = 60). In conclusion, both insulin and TSH caused an intracellular alkalinization, TSH markedly so, even in the presence of bicarbonate ions.
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PMID:Long-term effects of thyroid stimulating hormone and insulin on intracellular pH in FRTL-5 cells. 161 17

We have characterized the insulin-like growth factor-binding proteins (IGF-BPs) released by isolated sheep thyroid epithelial cells. Thyroid follicles were isolated with collagenase and cultured in Coon's modified F-12 M (0H medium) supplemented with insulin, cortisol, transferrin, glycyl-histidyl-lysine and somatostatin (5H medium) and TSH (6H medium). Conditioned 0H medium specifically bound both 125I-labelled IGF-I and -II, although binding capacity was reduced following acid-gel filtration to separate endogenous IGF-BP complexes, suggesting some destruction of BPs. The binding of 125I-labelled IGF-I or -II to conditioned (0H) medium was progressively displaced by increasing amounts of unlabelled homologous peptides, while fractionation on concanavalin A-Sepharose showed that the IGF-BPs consisted of both glycoprotein and non-glycoprotein components. The molecular sizes of the IGF-BPs were resolved by separation of 0H medium on SDS-PAGE and ligand blot analysis with 125I-labelled IGF-I or -II. Conditioned medium contained four specific binding species for IGF-II of 19, 30, 38 and 46 kDa; all but the smallest also binding radiolabelled IGF-I. Prior fractionation on concanavalin A-Sepharose showed that the 46 kDa binding species was a glycoprotein. Competition studies with increasing concentrations of unlabelled IGF-I or -II during ligand blotting suggested that the 46 and 30 kDa binding species had a greater affinity for IGF-II than IGF-I, while the 38 kDa had a greater relative affinity for IGF-I. Incubation of cells in 5H medium reduced the abundance of the 46 kDa binding protein, while incubation in 6H medium decreased the release of all binding protein species. Results show that isolated thyroid follicles released several forms of IGF-BP with differing relative affinities for IGF-I and -II. Gross changes seen in the presence of BPs between 0H, 5H and 6H media suggest acute hormonal control of release.
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PMID:Characterization of insulin-like growth factor-binding proteins secreted by isolated sheep thyroid epithelial cells. 169 63

The classical neurotransmitter acetylcholine (ACh) and the potential modulatory peptide somatostatin are colocalized in terminals of avian choroid neurons. We previously showed that exogenous somatostatin inhibits ACh release in the choroid coat (Gray et al., 1989b). In the present work we determine whether endogenous somatostatin plays a role in neuromodulation and what mechanisms are involved. To determine its role and its mode of secretion, voltage-sensitive Ca2+ channels in these terminals were identified pharmacologically using Ca2(+)-dependent K(+)-evoked ACh release. Release of the primary transmitter ACh was triggered in the presence of high K+ by Ca2+ influx primarily via dihydropyridine (DHP)-insensitive channels, while inhibition of ACh release occurred when L-type channels were activated by the DHP agonist Bay K 8644. The somatostatin antagonist cyclo(7-aminoheptanoyl-phe-D-trp-lys-thr (BZL)) (CyCam) blocks the inhibition of ACh release induced by the agonist Bay K 8644 and indicates that endogenous somatostatin may normally modulate ACh release. Additionally, nifedipine, a DHP antagonist, and pertussis toxin, known to antagonize somatostatin's effect on ACh release, both reverse the Bay K 8644 effect on ACh release. Although the release of labeled ACh in the first 3 min collection period was not significantly affected by CyCam or nifedipine alone, release in the first minute was enhanced by 50% in the presence of 10 microM nifedipine. Preincubation with CyCam alone also increased ACh release. These results support the hypothesis that endogenous somatostatin is physiologically released during the initial minute of depolarization in high K+ and that this release is mediated by DHP-sensitive Ca2+ channels.
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PMID:Endogenous modulation of ACh release by somatostatin and the differential roles of Ca2+ channels. 169 82

The insulin-like growth factors (IGFs) exist primarily bound to cell surface receptors or complexed to specific binding proteins (IGFBPs). The IGFBPs modulate the bioavailability of the IGFs and may enhance or inhibit IGF actions. Several distinct forms of IGFBPs have been described on the basis of size, immunological determinants, and distribution in biological fluids; the IGFBPs may differ as well in their biological function. Sheep thyroid cells produce IGFBPs under hormonal regulation. Cells grown in basal medium or with six-hormone (6H) medium supplements (transferrin, glycyl-histidyl-lysine, hydrocortisone, somatostatin, insulin, and TSH) release nonglycosylated BPs that migrate at 24, 27, 29, and 32 kDa on Western ligand blot. Cells cultured with the thyroid mitogens epidermal growth factor and phorbol ester release additional glycosylated IGFBPs of 40-44 kDa. Immunoprecipitation experiments indicate that 29- and 32-kDa IGFBPs are antigenically related to IGFBP-2, and the 40- to 44-kDa proteins are related to IGFBP-3. Using specific cDNA probes IGFBP-1, -2, and -3, we examined the regulation of IGFBP mRNA levels in sheep thyroid cultures. The rat IGFBP-2 cDNA probe hybridized to an approximately 1.6-kilobase mRNA species in cells under all culture conditions. However, IGFBP-3 mRNA was detectable only in epidermal growth factor- or phorbol ester-treated cells and appeared within 4 h, preceding the release of IGFBP-3 protein into the medium. The 6H additives, which stimulate differentiated function in thyroid cells, inhibited the mRNA levels of both IGFBP-2 and IGFBP-3. IGFBP-1 mRNA was not detectable. The distinct regulation of these IGFBPs suggest that they may play different biological roles in modulating thyroid physiology.
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PMID:Regulation of insulin-like growth factor-binding protein messenger ribonucleic acid levels in sheep thyroid cells. 170 62

Isolated sheep thyroid follicles release specific insulin-like growth factor-binding proteins (IGFBPs). Since IGFBPs can modulate IGF bioactivity, at least in vitro, their presence in thyroid tissue may influence synergistic interactions between TSH and endogenous IGF-I or -II which are known to control both thyroid growth and function. We have examined the hormonal control of IGFBP release in relation to iodine organification. Sheep thyroid follicles were isolated by incubation with collagenase and differential centrifugation, grown in Coon's modified Ham's F12M medium with the addition of transferrin, glycylhistidyl-lysine, somatostatin (3H), TSH, cortisol and insulin (6H), and maintained in OH (hormone-free) or 3H medium with or without further supplements for 48 h. Conditioned culture medium was separated by 8% sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis, transferred to nitrocellulose and incubated with 125I-labelled IGF-II followed by autoradiography (ligand blot). Additionally, the radioactive bands were cut from the filters and quantified by gamma-spectrometry. Iodine organification was assessed by incubation of follicles with 10(6) c.p.m. Na125I for 3 h before washing, solubilization in 0.1 mol NaOH/l and the precipitation of organified radioisotope with 10% (v/v) trichloroacetic acid. Cells conditioned in OH or 3H medium released specific IGFBPs of 46, 34, 28 and 19 kDa on ligand blot analysis. The proteins of 34 and 19 kDa were immunopositive on Western blot analysis using anti-bovine IGFBP-2 antiserum. The 46-kDa IGFBP was retained by Concanavalin A-Sepharose chromatography and demonstrated to be glycoprotein. This is probably ovine IGFBP-3. The addition of TSH, or TSH plus cortisol to OH or 3H medium significantly decreased the 125I-labelled IGF-II associated with the 34- and 28-kDa IGFBP species. All IGFBP species were substantially reduced in 6H medium, which was predominantly due to the effects of TSH and cortisol. When total 125I-labelled IGF-II associated with IGFBPs was considered, a significant (P less than 0.01) inverse correlation existed between IGFBP activity and iodine organification in the same cultures; the latter being greatest in OH or 3H medium supplemented with TSH and cortisol. None of these hormone additions altered the endogenous release of IGF-II by the cells. These results suggest that endogenous IGFs, under hormonal control, may modulate the action of endogenous IGF in the regulation of thyroid function.
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PMID:Hormonal regulation of insulin-like growth factor (IGF)-binding proteins secreted by isolated sheep thyroid epithelial cells: relationship with iodine organification. 171 78


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