bluuebunny/crossref_metadata_2025_split huggingface dataset:
IGF-I and serine protease inhibitor 2·1 nuclear transcript abundance in rat liver during protein restriction
Authors: Hayden J M , Straus D S 
Published: December 2008

Abstract
Restriction of dietary protein consumption of young male rats results in decreased growth velocity and a reduction in the abundance of hepatic IGF-I mRNA. It is not known whether the reduction in IGF-I mRNA abundance in the liver of protein-restricted rats results from a decrease in IGF-I gene transcription. In the present study, three experiments were performed with 4-week-old male rats to examine the effect of protein restriction on IGF-I gene transcription in liver. In these experiments, we monitored IGF-I nuclear transcripts (pre-mRNA) within total cellular RNA using a ribonuclease protection assay.
In the first experiment, a consistent decrease in IGF-I mRNA from animals fed isocaloric diets containing 20% (control), 12%, 8% and 4% protein (dietary effect, P<0·001) was not paralleled by a decrease (P>0·50) in IGF-I pre-mRNA. Two additional experiments examining the effect of 4% vs 20% protein diets yielded comparable results. Pooled results from these two studies (n=12/treatment) demonstrated that a 64% reduction (P<0·0001) in IGF-I mRNA abundance was not accompanied by a decrease in IGF-I pre-mRNA (1·17 vs 1·31 ±0·21 image density units for 4% and 20% protein treatments). Unlike IGF-I, the abundance of carbamyl phosphate synthetase-I (CPS-I) pre-mRNA and mRNA was comparably reduced (∼70%, P<0·001), indicating that the decrease in mRNA of this urea cycle enzyme during protein restriction occurs predominantly by a transcriptional mechanism. A common feature of all experiments was a pronounced variability in the expression of hepatic IGF-I pre-mRNA among animals, which was not diet specific. To test whether the variability in IGF-I gene transcription was correlated with variability in the transcription of another gene that is regulated by GH, we quantified the abundance of nuclear transcripts for the serine protease inhibitor 2·1 (SPI 2·1 gene. A positive association (r=0·81, P<0·0001) between SPI 2·1 and IGF-I nuclear transcripts was demonstrated. The correlation between IGF-I and SPI 21 transcripts was specific, because the quantity of IGF-I and CPS-I nuclear transcripts was not correlated in this study. Although transcription of the IGF-I and SPI 2·1 genes was similar, the abundance of SPI 21 mRNA was not altered by protein deprivation.
In summary, these studies indicated that protein restriction does not substantially alter the mean quantity of IGF-I nuclear transcripts, suggesting that the decrease in IGF mRNA occurs predominantly by a post-transcriptional mechanism. In addition, nuclear transcript abundance of the IGF-I and SPI 21 genes varies in a co-ordinate manner, supporting the hypothesis that transcription of these genes responds rapidly to a common variable factor such as plasma GH.
Journal of Endocrinology (1995) 145, 397–407
Consistent GH responses to repeated injections of GH-releasing hexapeptide (GHRP-6) and the non-peptide GH secretagogue, L-692,585
Authors: Fairhall K M , Mynett A , Smith R G , Robinson I C A F 
Published: December 2008

Abstract
GH release is normally stimulated by the naturally occurring GH-releasing factor (GRF). However, smaller GH-releasing peptides (GHRPs) and non-peptide analogues have been described which stimulate GH release in animals and man. Although these compounds release GH in vitro, their in vivo activity in conscious animals has proved more difficult to study since the GH responses are variable, and prone to desensitization. We now compare the GH-releasing properties of GHRP-6 and a novel benzolactam GH secretagogue L-692,585 using chronically cannulated guinea pigs and automated blood microsampling to study the effects of repeated exposure to these secretagogues. L-692,585 was approximately tenfold less potent than GHRP-6 for GH release, but it synergized strongly with GRF. Serial injections of GRF, GHRP-6 or L-692,585 at intervals of 60 or 90 min produced variable GH release which followed a cyclic pattern of responsiveness. Prolonging the pulse interval to 3 h produced more regular responses to both GHRP-6 and L-692,585. Continuous i.v. infusion of low doses of either secretagogue elicited an initial GH release, and amplified the spontaneous GH secretory pattern over the next 6 h. We conclude that L-692,585 and GHRP-6 share similar in vivo properties, and that intermittent responsiveness to frequent injections is similar for all three secretagogues, and is a property of the conscious animal rather than of any secretagogue type. More consistent responses can be obtained with less frequent injections that more closely match the endogenous GH rhythm, whereas continuous exposure to these secretagogues leads to amplified endogenous secretion. Our results show that the interpretation of in vivo effects of these peptide and non-peptide secretagogues will need to take account of their interaction with the endogenous mechanisms governing GH release.
Journal of Endocrinology (1995) 145, 417–426
Characteristics of the binding of 32P-labelled human relaxins to the human fetal membranes
Authors: Garibay-Tupas J L , Maaskant R A , Greenwood F C , Bryant-Greenwood G D 
Published: December 2008

Abstract
The two human relaxin genes termed H1 and H2 are expressed in the choriodecidua and placenta and have been proposed to act via specific receptors as local modulators of collagenolysis in the fetal membranes. Such receptors have been inferred, but not demonstrated, from studies of the effect of adding exogenous relaxin to these tissues. Thus conditions were optimized for the binding of 32P-labelled human relaxin H2 to membrane-enriched particulate fractions of human fetal membranes, amnion and chorion, with adhering decidua. The membrane protein concentration was optimal at 250 μg, when incubated at 27 °C for 60 min, at pH 7·5 with Mn2+ and Mg2+ ion concentrations of 2·0 mm. Incubation of membrane particulate fractions with increasing amounts of labelled relaxin H2 suggested the presence of a single class of binding sites with an affinity constant (Ka) of 2·15 nm. The binding was primarily to the chorion and decidua with very little to the amnion layer. The competition for binding of the 32P-labelled human relaxin H2 with unlabelled relaxin H2 gave an IC50 of 28 pm, while an IC50 of 60 pm and 280 pm was obtained for relaxin H1 and porcine relaxin respectively. In contrast, unlabelled guinea-pig relaxin inhibited this binding by only 10% even at a 1000-fold greater concentration than H2, and human recombinant insulin failed to inhibit even at a million-fold concentration of unlabelled relaxin H2.
Relaxins H2 and H1 can readily displace the binding of either 32P-labelled human relaxins H1 or H2 and gave very similar displacement curves. The binding affinity of relaxin H2, however, was fivefold higher than that of relaxin H1. These data provide evidence for the presence of a relaxin receptor that may preferentially bind relaxin H2.
Journal of Endocrinology (1995) 145, 441–448
Pituitary-adrenal function in the immature ovine foetus
Authors: McFarlane A C , Potocnik S , Towstoless M , Moritz K , Wintour E M 
Published: December 2008

Abstract
Pituitary-adrenal responses to intravenous infusion of ovine corticotrophin-releasing hormone (oCRH) or arginine vasopressin (AVP) and to haemorrhage were examined in the ovine foetus prior to 90 days of gestation (term 145–150 days). In chronically cannulated foetuses (n=8), between 74 and 84 days of gestation, basal ACTH levels were less than 20 pg/ml while cortisol levels were 6·5 ± 1·5 nmol/l (mean±s.e m.). Intravenous infusion of oCRH (1 μg/h for 60 min) or AVP (1 μg/h for 60 min) significantly increased ACTH (P<0·05 for both treatments) and cortisol (P<0·01 for both treatments) levels, although the response to both hormones was modest. In acutely studied foetuses of a similar age (70–90 days of gestation, mean 82·0 ± 1·4 days, n=7), exteriorization and progressive haemorrhage significantly (P<0·05) elevated ACTH levels from 117·4 ± 32·1 pg/ml to a maximal value of 329·2 ± 112·8 pg/ml, the maximal ACTH response corresponding to the removal of a volume of blood equivalent to 6·6 ±1·2% of the pre-haemorrhage body weight. The present study has demonstrated that the ovine foetal pituitary, in vivo, is responsive to exogenous and endogenous stimuli by mid-gestation and, at this age, although basal cortisol levels are low, the foetal adrenal is capable of responding to elevated ACTH levels in the short term.
Journal of Endocrinology (1995) 145, 455–460
Plasma clearance, tissue uptake and expression of pituitary peptide 23/pancreatitis-associated protein in the rat
Authors: Chakraborty C , Sharma S , Katsumata N , Murphy L J , Schroedter I C , Robertson M C , Shiu R P C , Friesen H G 
Published: December 2008

Abstract
The secretion of peptide 23 by rat pituitary cells is stimulated by growth hormone-releasing hormone and inhibited by somatostatin. Recent cloning of the cognate cDNA for peptide 23 revealed that it is identical to pancreatitis-associated protein (PAP). In the present study, the clearance and tissue uptake of recombinant peptide 23/PAP in normal adult male rats was assessed. The plasma half-life of recombinant peptide 23/PAP was 4·8 ±1·4 (s.d.) min. Maximal accumulation of radiolabelled peptide 23/PAP was observed in the kidney, stomach, small intestine and pancreas whereas negligible uptake was seen in the liver, lung or heart. Peptide 23/PAP was detected in a variety of tissue extracts using a radioimmunoassay. Extracts of ileum contained the highest concentrations of peptide 23/PAP. In situ hybridization analysis showed that peptide 23/PAP mRNA was highly expressed in the columnar epithelial cells of ileum, jejunum and duodenum. These observations demonstrate that peptide 23/PAP, a protein previously thought to be of pituitary origin, is widely expressed in the gastrointestinal tract and that it is rapidly removed from the circulation by the kidney and by tissues which express peptide 23/PAP.
Journal of Endocrinology (1995) 145, 461–469
Epidermal growth factor stimulates cell proliferation and inhibits iodide uptake of FRTL-5 cells in vitro
Authors: Asmis L M , Gerber H , Kaempf J , Studer H 
Published: December 2008

Abstract
In accordance with the available data most authors conclude that epidermal growth factor (EGF) has very little or no effect on FRTL-5 cells. This has been viewed as a serious handicap of this cell line. In the present study we cultivated three strains of FRTL-5 cells from different sources and assessed their response to EGF with regard to proliferation, function and differentiation.
Cell proliferation was assessed by counting in a Coulter cell counter after culturing cells at suboptimal conditions in well plates. Cell function was studied by measuring iodide uptake. Cell differentiation was examined immunocytochemically by staining monolayer cultures for thyroglobulin (Tg) and EGF receptor (EGFr) as well as morphologically by microscopical evaluation of monolayer cultures.
All three FRTL-5 cell lines investigated express EGFr. In two wild type FRTL-5 cell lines EGF stimulates growth, an effect that is enhanced by the presence of TSH, and partially inhibits iodide uptake. A third mutated strain of FRTL-5 cells does not respond to EGF. Tg expression can be demonstrated immunocytochemically in EGF-treated cells as well as in controls. Morphologically, in monolayer culture EGF-treated cells cannot be distinguished from controls.
Contrary to previous reports, these studies demonstrate EGF effects on FRTL-5 cells that are consistent with EGF effects established in other thyroid follicular cells.
Journal of Endocrinology (1995) 145, 513–520
Investigation into the potential physiological sources of rat milk IGF-I and IGF-binding proteins
Authors: Donovan S M , Hintz R L , Rosenfeld R G 
Published: December 2008

Abstract
We have previously reported the presence of IGF-I and IGF-binding proteins (IGFBP-2, -3 and -4) in rat milk. Herein, the potential sources of rat milk IGF-I and IGFBPs were investigated. Lactating dams (day 14 postpartum) were separated from their pups and injected intraperitoneally with 0·45 μCi 125I-IGF-I or 125I-IGFBP-3. After 3 h, serum and milk of rats receiving 125I-IGF-I contained 7642 ± 3121 and 14 455 ± 7837 c.p.m./ml respectively. Serum and milk of rats given 125I-IGFBP-3 contained 7232 ± 1366 and 10 371 ± 4091 c.p.m./ml respectively. Sephacryl S-200 gel filtration chromatography demonstrated that the 125I-IGF-I in both serum and milk was primarily in the 150 kDa IGF-binding complex, whereas the distribution of 125I-IGFBP-3 differed between serum and milk. In serum, most of the 125I-IGFBP-3 was in the 150 kDa fraction, while most 125I-IGFBP-3 in milk was in the 40 kDa fraction. Northern analysis of liver showed IGFBP-1 and -3 mRNA expression, with variable expression of IGFBP-2 and -4 mRNA. In contrast, mammary tissue expressed only IGFBP-2 and -4 mRNA, suggesting that these IGFBPs in milk may arise from de novo synthesis within the mammary gland. The lack of detectable IGFBP-3 mRNA in mammary tissue and the translocation of 125I-IGFBP-3 from the serum suggest that milk IGFBP-3 arises from the maternal circulation.
Journal of Endocrinology (1995) 145, 569–578
PROTEINS IN TISSUE EXTRACTS WHICH BIND INSULIN-LIKE GROWTH FACTOR BINDING PROTEIN-3 (IGFBP-3)
Authors: Hodgkinson S. , Fowke P. , Somai N. Al , McQuoid M. 
Published: December 2008

ABSTRACT
Membrane associated IGFBP-3 is now known to play a role in the modulation of IGF at the cellular level, but mechanisms involved in cell membrane binding are far from certain. In this study we report the identification and initial structural characterisation of proteins in a range of sheep and rat tissues which specifically bind recombinant human non-glycosylated IGFBP-3. Tissues were homogenised in Tris HCl (0.1 M, pH 7.4), containing proteolytic enzyme inhibitors and the residues re-extracted in buffer containing SDS and Triton X-100 (both 1% w/v) prior to analysis. These were subjected to SDS-PAGE, electro-blotted onto nitrocellulose and subjected to ligand blot analysis (LBA) using radioiodinated IGFBP-3 as ligand. LBA revealed a major band of binding activity migrating at 60 kDa in extracts of rat muscle while sheep muscle contained forms of 52 and 40 kDa as the principal species and ovine pancreatic extracts an abundance of the 40 kDa variant alone. Distribution of the binding activity appears tissue specific. Apart from skeletal muscle, pancreas and a small amount of the 52 kDa form in pituitary, analysis revealed no evidence of IGFBP-3 binding in a range of other sheep tissues including liver, kidney, spleen, intestine, adrenal, brain, mammary, uterus, ovary and plasma. The binding activity is TCA precipitable, trypsin digestible, dose responsive and relatively specific for IGFBP-3 since the related proteins recombinant human IGFBP-2 and purified caprine IGFBP-4 failed to bind. Additionally, IGFBP-3 binding to these species appeared unaffected by presaturation of IGFBP-3 with IGF-I, nor by their transient acidification which together with molecular weight estimates and their pattern of tissue distribution suggests they are not related to the acid labile subunit of the ternary 150 kDa IGFBP complex. IGFBP-3 binding and molecular mobility of the species were unaffected by sample reduction but binding was suppressed in a concentration dependent fashion by heparin. Finally LBA using 125I-Concanavalin A revealed the 40 kDa species to be glycosylated while the 52 kDa form was not. Functions of these novel proteins in targeting or modulating IGF activity at the cellular level remain to be clarified.
Effect of restriction of placental growth on expression of IGFs in fetal sheep: relationship to fetal growth, circulating IGFs and binding proteins
Authors: Kind K L , Owens J A , Robinson J S , Quinn K J , Grant P A , Walton P E , Gilmour R S , Owens P C 
Published: December 2008

Abstract
To determine whether tissue production of the IGFs is altered when fetal growth is retarded, IGF-I and -II mRNAs were measured in tissues of fetal sheep subjected to placental restriction and the relationships between IGF gene expression, circulating IGF protein and fetal growth were examined. The majority of potential placental attachment sites were surgically removed from the uterus of 12 non-pregnant ewes to restrict placental size in a subsequent pregnancy. Blood and tissues were collected at 121 days of gestation (term=150) in 12 fetuses with restricted placental size and eight normal fetuses. IGF-I and IGF-II mRNA was detected by solution hybridization/ribonuclease protection assay in placenta and all fetal tissues studied. IGF-I mRNA was most abundant in skeletal muscle and liver and IGF-II mRNA was highest in kidney and lung. Restriction of placental size reduced fetal weight by 17% and reduced the pO2 (18%) and glucose concentration (23%) of fetal blood. Placental restriction also reduced IGF-I mRNA in fetal muscle (P<0·002), lung (P<0·05) and kidney (P<0·01) but had no significant effect on IGF-II mRNA in any tissue. IGF-I mRNA in fetal liver, kidney and skeletal muscle correlated positively with the concentration of IGF-I protein in fetal blood (P<0·01). There was no relationship between the concentration of IGF-II protein in fetal blood and IGF-II mRNA in any fetal tissue examined. The concentration of IGF-binding protein-3 (IGFBP-3) in fetal arterial blood plasma measured by RIA correlated positively with fetal weight and with plasma IGF-I. This study shows that restriction of placental growth in sheep reduces circulating levels of IGF-I and IGFBP-3 in the sheep fetus and reduces the capacity of the fetus to produce IGF-I at a number of tissue sites. Altered production of IGF-I, but not IGF-II, by fetal tissues may contribute to retarded fetal growth.
Journal of Endocrinology (1995) 146, 23–34
Corticotrophin-releasing hormone (CRH)-binding protein interference with CRH antibody binding: implications for direct CRH immunoassay
Authors: Linton E A , Perkins A V , Hagan P , Poole S , Bristow A F , Tilders F , Corder R , Wolfe C D A 
Published: December 2008

Abstract
Direct immunoassay of plasma corticotrophin-releasing hormone (CRH) is potentially subject to interference from high levels of CRH-binding protein (CRH-BP) that exist in the human circulation. In this study, we tested the effect of CRH-free, native CRH-BP (6·4 nmol/l) purified from human plasma, CRH-BP diluent alone, normal human plasma (containing 5·8 nmol endogenous CRH-BP/1) and normal sheep plasma (containing no CRH-BP) on the binding of 125I-labelled CRH tracer to five N-terminal and four C-terminal CRH antibodies. All anti-(1–20)CRH N-terminal antibody dilution curves displayed marked inhibition of binding in the presence of purified CRH-BP and human plasma in comparison with the curves with the control diluent or sheep plasma. Almost no inhibition of binding was obtained with any of the C-terminal antibodies (all directed against epitopes within the last six amino acids of CRH) and the four dilution curves were nearly superimposable. Liquid-phase CRH IRMAs were then developed with different combinations of two of each of the N- and C-terminal antibodies, using radiolabelled IgG prepared from purified C-terminal antisera as tracer and raw N-terminal antisera as the link antibodies to the separating system. The addition of dilutions of purified CRH-BP over the range 1·25–20 nmol/l to the IRMA standard curve in assay buffer resulted in a dose-dependent reduction in the signal; with 5 nmol CRH-BP/1, a level commonly found in human plasma, the reduction in binding was 67% and 81% in two different IRMAs at a CRH concentration of 631 pmol/l. With endogenous CRH-BP in human plasma, a dose-dependent inhibition of binding similarly resulted, with the plasma containing the most CRH-BP causing the greatest inhibition. Since plasma CRH-BP levels in humans vary widely, direct plasma IRMA using these type of antibodies will give inaccurate results and initial extraction of the CRH is necessary. Methanol extraction of synthetic or endogenous CRH is shown to be both highly efficient and unaffected by variable amounts of endogenous or exogenous CRH-BP; it is therefore suitable as the first step in plasma CRH measurement by IRMA.
Journal of Endocrinology (1995) 146, 45–53
Acute hyperinsulinemia, androgen homeostasis and insulin sensitivity in healthy man
Authors: Ebeling P , Stenman U-H , Seppälä M , Koivisto V A 
Published: December 2008

Abstract
The acute effects of hyperinsulinemia on androgen homeostasis and a possible association of androgens to insulin sensitivity, serum lipids and lipoproteins and to lipid oxidation were examined in 19 healthy males (27 ± 1 yrs, body mass index 24 ± 1 kg/m2). In each subject, a 240 min euglycemic hyperinsulinemic clamp was performed and glucose and lipid oxidation were determined by indirect calorimetry. During hyperinsulinemia serum sex hormone-binding globulin (SHBG) concentration decreased by 5% (P<0·01), insulin-like growth factor binding protein (IGFBP-1) by 88% (P<0·001) and dehydroepiandrosterone sulphate (DHEAS) by 12% (P<0·001), with no change in total or free testosterone concentrations. In the basal state, IGFBP-1 and C-peptide were inversely related (r= −0·54, P<0·05). Fasting concentrations of serum free testosterone (r=0·59, P<0·01) and DHEAS (r=0·47, P<0·05) correlated positively with serum free fatty acid (FFA) concentrations during hyperinsulinemia, but not with fasting FFA level. Lipid oxidation rate in the basal state correlated positively to the decline in SHBG (r=0·61, P<0·01) and DHEAS concentrations (r=0·62, P<0·01) during hyperinsulinemia. While the fasting serum high density lipoprotein cholesterol level correlated positively with the insulin-induced decline in DHEAS level (r=0·58, P<0·01), no associations were found between serum androgens and total cholesterol, low density lipoprotein cholesterol or triglyceride concentrations. Insulin sensitivity was not related to SHBG, IGFBP-1, DHEAS or testosterone concentrations. It is concluded that, in the healthy man with normal androgen homeostasis, (1) acute hyperinsulinemia decreases SHBG, IGFBP-1 and DHEAS concentrations, (2) the relative insulin-induced decline of IGFBP-1 level is 18-fold greater than that of the SHBG level, (3) androgens may maintain lipolysis during hyperinsulinemia and (4) there is no association between physiological androgen concentrations and insulin sensitivity.
Journal of Endocrinology (1995) 146, 63–69
Effect of ovarian steroid hormones and the presence of the fetus on oxytocin gene expression in the uterus
Authors: Higuchi T , Liu C-X , Saito H , Negoro H , Matsukawa S 
Published: December 2008

Abstract
Oxytocin (OT) is a neurohypophysial hormone with potent stimulating activity of the pregnant uterus, but its physiological role in parturition is still unclear. Recently, OT was found to be synthesized in the pregnant uterus, indicating that OT originating from the uterus, not from the posterior pituitary gland, may trigger the onset of labour. In order to define the factors responsible for the induction of uterine OT, the effect of ovarian steroid hormones and conceptus on the induction of OT mRNA in the rat uterus was examined by Northern and dot blot hybridization analysis. OT mRNA in the uterus started to increase on day 14 of pregnancy and showed very high levels at the time of parturition. Uterine OT mRNA was not altered by any steroid treatment, oestradiol-17β (0·2 μg), progesterone (4 mg) or both in combination, for 6 days. The gravid horn of the uterus had 3·6-fold as much OT mRNA as the non-gravid horn on day 21 of pregnancy in hemipregnant rats with one ligated oviduct. The ovarian steroid hormones could not induce accumulation of OT mRNA in the uterus of ovariectomized rats, at least under the conditions used, but the presence of a conceptus may be critical for the very high levels of OT mRNA.
Journal of Endocrinology (1995) 146, 81–85