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: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prior research indicates that growth hormone (GH) cell differentiation can be induced prematurely by treatment with glucocorticoids in vitro and in vivo. However, the nature of these responses has not been fully characterized. In this study, the time course of corticosterone induction of GH-secreting cells in cultures of chicken embryonic pituitary cells, responsiveness of differentiated somatotrophs to GH secretagogues, localization of somatotroph precursor cells within the pituitary gland, and the effect of corticosterone on GH gene expression were determined to better define the involvement of glucocorticoids in somatotroph recruitment during development. Anterior pituitary cells from embryonic day 12 chicken embryos were cultured in 10(-9) M corticosterone for 4 to 48 h and were then subjected to reverse haemolytic plaque assays (RHPAs) for GH. Corticosterone treatment for as short as 16 h increased the percentage of GH cells compared with the control. When corticosterone was removed after 48 h and cells were cultured for an additional 3 days in medium alone, the percentage of GH secretors decreased but remained greater than the proportion of somatotrophs among cells that were never treated with corticosterone. To determine if prematurely differentiated somatotrophs were responsive to GH secretagogues, cells were exposed to corticosterone for 48 h and then subjected to GH RHPAs in the presence or absence of GH-releasing hormone (GHRH) or thyrotropin-releasing hormone (TRH). Approximately half of the somatotrophs induced to differentiate with corticosterone subsequently released more GH in response to GHRH and TRH than in their absence. The somatotroph precursor cells were localized within the anterior pituitary by culturing cells from the caudal lobe and cephalic lobe of the anterior pituitary separately. Corticosterone induction of GH cells was substantially greater in cultures derived from the caudal lobe of the anterior pituitary, where somatotroph differentiation normally occurs. GH gene expression was evaluated by ribonuclease protection assay and by in situ hybridization. Corticosterone increased GH mRNA in cultured cells by greater than fourfold. Moreover, corticosterone-induced somatotroph differentiation involved GH gene expression in cells not expressing GH mRNA previously, and the extent of somatotroph differentiation was augmented by treatment with GHRH in combination with corticosterone. We conclude that corticosterone increases the number of GH-secreting cells within 16 h, increases GH gene expression in cells formerly not expressing this gene, confers somatotroph sensitivity to GHRH and TRH, and induces GH production in a precursor population found primarily in the caudal lobe of the anterior pituitary, a site consistent with GH localization in adults. These findings support the hypothesis that glucocorticoids function to induce the final stages in the differentiation of fully functional somatotrophs from cells previously committed to this lineage.
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PMID:Somatotroph recruitment by glucocorticoids involves induction of growth hormone gene expression and secretagogue responsiveness. 1137 20

In agreement with recent studies showing a deleterious effect of growth hormone treatment in critically ill patients, preliminary data showed that insulin-like growth factor I (IGF-I) administration increased the mortality rate of rats with ischemic acute renal failure (ARF). The present study was designed to investigate the mechanism responsible for this unexpected effect. Male rats with ischemic ARF were given subcutaneous IGF-I, 50 microg/100 g at 0, 8, and 16 h after reperfusion (ARF+IGF-I, n = 5) or were untreated (ARF, n = 5). A group of 5 sham-operated rats were used as controls. Rats were killed 48 h after declamping, and the following studies were performed: in serum, creatinine and urea nitrogen; and in kidneys, histologic damage score, cellular proliferation by bromodeoxyuridine labeling, apoptosis by morphologic criteria, macrophage infiltration by immunohistochemistry using a specific antibody against ED-1, neutrophil infiltration by naphthol AS-D chloroacetate esterase staining, and levels of IGF-I and IGF-I receptor mRNA by RNase protection assay. ARF and ARF+IGF-I groups had a severe and similar degree of renal failure. Kidney damage was histologically more evident in ARF+IGF-I (1.9 +/- 0.1) than in ARF (1.3 +/- 0.2) rats, and the number of neutrophils/mm(2) of tissue was significantly greater in ARF+IGF-I than in ARF rats at the corticomedullary junction (52.3 +/- 5.2 versus 37.2 +/- 4.1) as well as at the renal medulla (172.5 +/- 30.0 versus 42.1 +/- 9.6). No other differences between the groups were found. It is concluded that IGF-I treatment enhanced the inflammatory response in rats with ischemic ARF. Cell toxicity derived from increased neutrophil accumulation might play a key role in the greater mortality risk of critically ill patients that are treated with growth hormone.
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PMID:Exacerbated inflammatory response induced by insulin-like growth factor I treatment in rats with ischemic acute renal failure. 1151 83

The aim of this work was to study the influence of the endocrine balance between thyroid hormones, insulin and growth hormone (GH) on the regulation of insulin-like growth factor binding proteins (IGFBPs), complementing a study previously reported for insulin-like growth factors (IGFs) in similar populations. Serum concentrations of IGFBPs-1 to -3 were assayed by Western ligand blot and their mRNA expression in the liver assayed by RNase protection assay in the hypothyroid populations: thyroidectomized and mercapto-1-methylimidazole (MMI)-treated neonates, and thyroidectomized adult rats at different periods after thyroidectomy. Serum concentrations of insulin, GH and IGF-I were increased in thyroidectomized neonates and decreased in the other populations. IGFBPs-1 and -2 increased 79% and 50% respectively in thyroidectomized neonatal rats compared with control at 15 days after thyroidectomy, whereas only IGFBP-2 increased (87%) in MMI-treated neonates, which had low serum insulin and GH compared with control on the same days. In thyroidectomized adult rats, IGFBPs-1 and -2 decreased 60% compared with controls on all days studied. Furthermore, when streptozotocin was administered to thyroidectomized neonates and insulin was given to thyroidectomized adult rats to restore insulin to control values in both groups, a differential regulation was found for IGFBPs-1 and -2. The transcriptionally induced decrease in IGFBP-3 (20-25% compared with control in neonates and 50% in adult rats), however, seemed to be regulated by GH and IGF-I. The similarity of changes in IGFBPs found in hypothyroid, undernourished and streptozotocin-induced diabetic neonatal rats suggests that the regulatory effect of insulin or GH on the IGFBPs requires the reduced biologically active thyroid hormone that is found in these three populations.
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PMID:Influence of hypothyroidism on circulating concentrations and liver expression of IGF-binding proteins mRNA from neonatal and adult rats. 1183 54

Infusion of pigs with an insulin-like growth factor-I (IGF-I) analogue (LongR(3)IGF-I) that does not bind to IGF-binding proteins decreases growth rate and the plasma concentration of growth hormone (GH), IGF-I, IGFBP-3, and insulin. This study was designed to determine whether the decrease is due to changes in IGF-I and IGFBP-3 gene expression. IGF-I or LongR(3)IGF-I (180 microg/kg/day) was infused into 55-kg finisher pigs for 4 days using Travenol infuser pumps. Plasma IGF-I concentration was measured by radioimmunoassay and plasma IGFBP-3 and IGFBP-2 were estimated by Western ligand blotting. Steady-state levels of IGF-I and IGFBP-3 mRNA were measured by RNase protection assay. Neither IGF-I nor LongR(3)IGF-I had a significant effect on hepatic IGF-I class 1 mRNA expression, whereas hepatic IGF-I class 2 mRNA expression was significantly reduced by both peptides. Plasma IGFBP-3 levels were unaffected by IGF-I treatment but were reduced by LongR(3)IGF-I treatment. The decrease in IGFBP-3 was not due to decreased gene expression in porcine liver or kidney, since neither IGF-I nor LongR(3)IGF-I treatment altered IGFBP-3 mRNA. This study infers a direct effect of the IGF analogue LongR(3)IGF-I on GH through its inhibition of plasma IGF-I concentration and class 2 IGF-I mRNA. The decrease in plasma IGFBP-3 was not accompanied by a decrease in hepatic or renal IGFBP-3 mRNA, suggesting that in this case, plasma IGFBP-3 protein levels are posttranslationally regulated or are derived from tissues other than liver or kidney.
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PMID:Short-term infusion of LongR(3) insulin-like growth factor (IGF)-I decreases hepatic IGF-I mRNA but not IGF binding protein-3 mRNA expression in pigs. 1203 Jul 78

Using radioimmuno- and ribonuclease protection assays, we examined the effects of gonadotropin-releasing hormone and its analogs on the growth hormone mRNA level and growth hormone secretion in common carp (Cyprinus carpio) pituitary fragments with static incubation. After a 24 h treatment, sGnRH ([Trp(7),Leu(8)]-LHRH) and sGnRH-A ([D-Arg(6),Pro(9)]-LHRH) (0.1 nM-1 microM) elevated the GH mRNA level and stimulated the GH secretion in a dose-dependent manner, with a higher potency for sGnRH-A. In a time-course experiment, the function of sGnRH and sGnRH-A (10 nM) on GH secretion was observed after 6 h incubation, while no action on the GH mRNA level were noted until 12 h after treatment. Comparing mammalian GnRH, avian GnRH and piscine GnRH, sGnRH and sGnRH-A showed the highest potency in increasing GH mRNA level and GH-release, followed by cGnRH-II ([His(5),Tyr(8)]-LHRH), and finally LHRH and LHRH-A([D-Trp(6), Pro(9)]-LHRH). These findings, taken together, suggest that GnRH not only can influence GH release, but also play a role in the regulation of GH synthesis.
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PMID:Effects of gonadotropin-releasing hormone on growth hormone secretion and gene expression in common carp pituitary. 1203 58

Hormones released from the pituitary have been shown to regulate the expression of different proteins in the central nervous system. We wanted to examine whether peripheral administration of bovine growth hormone (bGH) regulates the expression of delta-opioid receptor (DOR) in the cerebral cortex and cerebellum. Expression of the DOR protein was quantified using Western blot densitometry. DOR mRNA was quantified with a solution hybridization RNase protection assay. Hypophysectomized (Hx) and untreated normal female rats were included in the study. All Hx rats were hormonally treated with cortisol (400 microg/kg/day) and L-thyroxine (10 microg/kg/day) for 19 days. Hypophysectomy resulted in a threefold increase in cerebral cortex and a twofold increase in cerebellum of the DOR protein compared with normal rats. One subgroup of Hx rats received bGH (1 mg/kg body weight) as a daily subcutaneous injection for 19 days. This treatment normalized the levels of DOR protein in the cerebral cortex and cerebellum. Immunohistochemical experiments showed that GH decreased DOR expression especially in layers II-VI in cerebral cortex and in stratum moleculare in cerebellum. Quantification of DOR mRNA by solution hybridization RNase protection assay corresponded to the DOR protein measurements. We conclude that the expression of DORs in cerebral cortex and cerebellum is regulated by GH.
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PMID:Expression of delta opioid receptor mRNA and protein in the rat cerebral cortex and cerebellum is decreased by growth hormone. 1254 5

A cDNA library from the liver of a growth hormone (GH)-treated hypophysectomized rat was constructed and screened for GH-inducible genes (GIGs). Three cDNAs specific for putative GIG mRNAs (GIG-3, -7 and -12) were isolated and, when sequenced, were found to be homologous to portions of rat hemopexin, a Class 2 acute-phase gene. Hemopexin is an essential heme scavenger produced primarily in the liver, which upon binding to free heme, transports it to the liver where the heme iron is re-utilized. Hemopexin has not been previously described as being GH-responsive. GIG-3 and GIG-12 encode overlapping portions of the entire coding sequence starting within a few hundred base pairs from the 5' end of the hemopexin mRNA, and GIG-7 encodes the 3'-most end of the hemopexin mRNA. Northern analysis and ribonuclease protection assays of RNA from livers of control rats using the cDNA probes demonstrated a major transcript of approximately 2.0 kb. The hemopexin mRNA was low or undetectable in livers of hypophysectomized rats. Daily treatment with bovine growth hormone (bGH) for 10 days restored hemopexin mRNA to levels comparable or greater than that of intact rats. GH-dependence in cultured rat H4IIE hepatoma cells was then examined. Using hemopexin cDNA probes (GIG-3, -7, and -12) we identified a mRNA on Northern blots, which increased in concentration following bGH, compared with untreated cells. When measured by ribonuclease protection assay, a maximal increase in hemopexin mRNA concentration was obtained following 4-6 h of bGH administration. We conclude that hemopexin is a GH-inducible gene in rat liver in vivo and in cultured rat hepatoma cells.
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PMID:Identification of hemopexin as a GH-regulated gene. 1285 Feb 85

Exposure to cortisol inhibits prolactin (PRL) release from the tilapia pituitary within 10-20min through a plasma membrane-associated, non-genomic pathway. In the present study, in vitro effects of cortisol on the release and mRNA levels of two PRLs (PRL(188) and PRL(177)) and growth hormone (GH) were examined in the organ-cultured pituitary of the Mozambique tilapia, Oreochromis mossambicus. The PRL release was significantly greater in hyposmotic (300mOsmolal) than in hyperosmotic (350mOsmolal) medium during the 2-8h of incubation. The mRNA levels of two PRLs, as estimated by RNase protection assay, were increased after 8h in hyposmotic medium. Cortisol (200nM) inhibited the release of two PRLs under hyposmotic conditions within 1h, and the inhibitory effects lasted for 24h. Cortisol also reduced the gene transcription of both PRLs during 2-8h of incubation but not after 24h. No effect of cortisol was observed on PRL release or on its mRNA levels under hyperosmotic condition. There was no significant effect of medium osmolality on the release or mRNA levels of GH during 8h of incubation. However, GH release was significantly stimulated by cortisol after 4h, and the effect lasted for 24h under both hyposmotic and hyperosmotic conditions. Cortisol also caused a significant increase in GH mRNA levels at 8 and 24h. These results suggest that cortisol inhibits PRL release from the tilapia pituitary through non-genomic and also through transcriptional pathways, while stimulating GH release through classical genomically mediated glucocorticoid actions.
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PMID:In vitro effects of cortisol on the release and gene expression of prolactin and growth hormone in the tilapia, Oreochromis mossambicus. 1464 51

The effects of food deprivation on the hepatic level growth hormone receptor (GHR) were investigated in black seabream (Acanthopagrus schlegeli) both at the protein level (by radioreceptor assay) and at the mRNA level (by ribonuclease protection assay). Serum levels of growth hormone (GH) and triiodothyronine (T(3)) were also measured. Condition factor and hepatic proximate composition of the fish were also assessed. Significant decrease in hepatic GHR binding was recorded as early as on day 2 of starvation. On day 30 this decrease was even more pronounced, with the level in the starved fish reaching less than 20% the fed control level. A concomitant decrease in the hepatic GHR mRNA content was also noted during this period, with a progressive decrease from day 2 to day 30 of starvation. The extent of decrease in the mRNA content was less pronounced than the decrease in receptor binding, with the hepatic GHR mRNA content in the day 30 starved fish representing approximately 30% of the level in the fed control. In large contrast, serum GH level increased progressively during starvation. After 30 days of starvation, serum GH levels in the starved fish were more than three times the concentration found in the fed control. Serum T(3) levels, on the other hand, decreased during starvation, with the difference reaching significance on day 15 and day 30. After 30 days of starvation, serum T(3) levels in the starved fish were only approximately 40% the concentration found in the fed control. The hepatic lipid content exhibited an increasing trend during starvation. On day 30 the hepatic lipid content of the starved fish had doubled the level found in the fed control. However, the hepatic protein content did not exhibit much change during starvation. There was also a minor decrease in the moisture content of the liver during starvation, but the condition factor of the fish as a whole registered a gradual decrease during the course of food deprivation.
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PMID:Effects of food deprivation on expression of growth hormone receptor and proximate composition in liver of black seabream Acanthopagrus schlegeli. 1508 94

The promoter controlling expression of a major bovine growth hormone (GH) receptor (GHR) mRNA variant, GHR 1A, contains a common DNA element for transcription factors hepatocyte nuclear factor 4alpha (HNF-4alpha), hepatocyte nuclear factor 4gamma (HNF-4gamma), and chicken ovalbumin transcription factor II (COUP-TFII). Expression of GHR 1A mRNA is decreased in the liver of dairy cows at parturition. The objective of this study was to determine whether reduced expression of GHR 1A mRNA in dairy cows at parturition is associated with changed expression of HNF-4alpha, HNF-4gamma, or COUP-TFII mRNA. Liver biopsy samples were taken from multiparous Holstein cows 7 to 23 d before parturition, within 24 h after parturition (i.e., at parturition), and 8 to 18 d after parturition, and the relative amounts of GHR 1A, insulin-like growth factor-I (IGF-I), HNF-4alpha, HNF-4gamma, and COUP-TFII mRNA in these samples were measured by ribonuclease protection assays. As expected, expression of GHR 1A, total GHR, and IGF-I mRNA was decreased at parturition, compared with that detected prepartum or during the postpartum period. Expression of HNF-4alpha and COUP-TFII mRNA was unchanged, but that of HNF-4gamma mRNA was increased at parturition. The same study was also conducted in multiparous Angus cows 7 to 23 d before parturition, at parturition, and 8 to 18 d after parturition. Neither expression of GHR 1A, total GHR, or IGF-I mRNA, nor expression of HNF-4alpha, COUP-TFII, or HNF-4gamma mRNA was changed in the liver of beef cows at parturition. These results together suggest that, at the molecular level, decreased expression of GHR 1A mRNA in the liver of dairy cows at parturition may involve increased expression of HNF-4gamma mRNA and that, at the systemic level, decreased expression of GHR 1A mRNA is not a direct result of the end of pregnancy, parturition, or the initiation of lactation.
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PMID:Expression of growth hormone receptor 1A mRNA is decreased in dairy cows but not in beef cows at parturition. 1577 5


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