bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of cortisol on hepatic and renal gluconeogenic enzyme activities in the sheep fetus during late gestation
Authors: Fowden A. L. , Mijovic J. , Silver M. 
Published: December 2008

ABSTRACT
The effects of cortisol on hepatic and renal gluconeogenic enzyme activities were investigated in sheep fetuses during late gestation and after experimental manipulation of plasma cortisol levels by fetal adrenalectomy and exogenous infusion of cortisol. Hepatic and renal gluconeogenic enzyme activities increased with increasing gestational age in parallel with the normal rise in fetal cortisol levels towards term (146± 2 days). For the majority of enzymes this increase in activity towards term was prevented when the prepartum cortisol surge was abolished by fetal adrenalectomy and stimulated prematurely in fetuses younger than 130 days by exogenous infusion of cortisol. When the data from all the fetuses were combined irrespective of treatment or gestational age, there were significant positive correlations between the log plasma cortisol concentration in utero and the activities of glucose-6-phosphatase, fructose diphosphatase, phosphoenolpyruvate carboxykinase and aspartate transaminase in the fetal liver and kidney, and pyruvate carboxylase in the fetal liver but not in the kidney. No correlation was observed between log plasma cortisol and alanine aminotransferase activity in either fetal liver or kidney. These findings show that cortisol is a physiological regulator of most of the fetal gluconeogenic enzymes and enhances the glucogenic capacity of the sheep fetus during late gestation.
Journal of Endocrinology (1993) 137, 213–222
Angiotensin II (AII) and adrenal gland AII receptors in rats with congenital hypothyroidism
Authors: Matilla M. J. , Montiel M. , Jiménez E. 
Published: December 2008

ABSTRACT
Plasma angiotensin II (AII) concentration, plasma renin concentration (PRC), lung angiotensin-converting enzyme (ACE) activity and adrenal gland AII receptor isoforms have been evaluated in the postnatal development of the rat, in order to determine the alterations of the renin-angiotensin system (RAS) which occur in congenital hypothyroidism. The developmental AII profiles observed in control and hypothyroid rats were quite similar. Thus, AII was elevated at birth and declined at week 5 of life to reach adult values. However, AII levels were lower in hypothyroid than in euthyroid animals before their stabilization. On the other hand, PRC in newborn hypothyroid and euthyroid animals was higher than in adulthood, being significantly increased immediately after birth in hypothyroid rats. Pulmonary ACE activity in both experimental groups was low at birth and increased with age. This increase was greater in euthyroid rats than in congenitally hypothyroid animals from day 28 of life. These results confirm that plasma AII levels in rats are predominantly controlled by plasma renin activity, although other factors, such as renin substrate availability, may be responsible for the reduced plasma AII concentration in congenital hypothyroidism during the first weeks of life.
The developmental profile of the adrenal gland AII receptor showed four isoforms, with pI values of 6·8, 6·7, 6·5 and 6·3. AII receptor-complex expression increased with age but, in congenitally hypothyroid rats, a higher induction of AII receptor isoforms migrating to pI 6·8, 6·5 and 6·3 was observed.
These findings show that thyroid hormone deficiency in early life can have an important role in the postnatal induction of the RAS components, which may be essential for the regulation of blood pressure, and for fluid and electrolyte balance in developing rats.
Journal of Endocrinology (1993) 137, 231–238
A double-staining technique for detection of growth hormone and insulin-like growth factor-I binding to rat tibial epiphyseal chondrocytes
Authors: Bentham J. , Ohlsson C. , Lindahl A. , Isaksson O. , Nilsson A. 
Published: December 2008

ABSTRACT
In the present study a double-staining technique was developed to investigate simultaneous GH and insulin-like growth factor-I (IGF-I) binding to chondrocytes in a monolayer cell culture.
Rat tibial epiphyseal chondrocytes were isolated by enzymatic digestion and cultured in monolayer. GH and IGF-I were labelled with biotin. The affinity of the biotin-labelled ligands was compared with unlabelled ligands in a radioreceptor assay.
To study the distribution of GH and IGF-I binding in the monolayer, chondrocytes were incubated with biotinylated ligands with or without an excess of unlabelled ligands, followed by incubation with Vectastain ABC complex, which was then reacted with diaminobenzidine (DAB). Double staining was accomplished by carrying out the first reaction with DAB in the presence of nickel ammonium sulphate to give a black precipitate, followed by incubation with the second ligand, then ABC complex and finally DAB in the absence of nickel ammonium sulphate to give a brown stain. The presence of type-II collagen was demonstrated by immunohistochemistry and used as a marker for differentiated chondrocytes.
Biotin-labelled GH and biotin-labelled IGF-I exhibited dose-dependent displacements of 125I-labelled GH and 125I-labelled IGF-I respectively from the chondrocytes in a radioreceptor assay. The displacement curves were identical to those of unlabelled ligands indicating that the affinity was unaltered. Binding of biotinylated GH to cells was seen throughout the culture in regions where there was little or no type-II collagen staining. IGF-I binding was predominantly localized to cells at high density; areas which also showed a high degree of staining for type-II collagen.
The different locations of binding suggest that epiphyseal chondrocytes in monolayer culture comprise a heterogeneous cell population and that IGF-I and GH have different target cells.
Journal of Endocrinology (1993) 137, 361–367
Regulation of adipocyte precursor DNA synthesis by acidic and basic fibroblast growth factors: interaction with heparin and other growth factors
Authors: Butterwith S. C. , Peddie C. D. , Goddard C. 
Published: December 2008

ABSTRACT
The development of adipose tissue is dependent on the growth and differentiation of fibroblast-like adipocyte precursor cells. Culture of adipocyte precursor cells in vitro has provided an ideal system for identifying potential regulators of proliferation and differentiation. We have demonstrated that both acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) stimulate chicken adipocyte precursor DNA synthesis in a dose-dependent manner up to a concentration of 100 μg aFGF/l and 1 μg bFGF/l. The effect of bFGF was biphasic, so that in incubations with 25 μg bFGF/l, DNA synthesis was not significantly different from controls. In the presence of heparin, stimulation of DNA synthesis at 25 μg bFGF/l was 1·6-fold greater than at a concentration of 1 μg bFGF/l. Addition of heparin to incubations containing aFGF reduced the concentration required for maximum stimulation of DNA synthesis to 1 μg/l. Cells incubated with aFGF (1–100 μg/l) in combination with insulin-like growth factor-I (IGF-I), platelet-derived growth factor, transforming growth factor-α or transforming growth factor-β1 (TGF-β1) exhibited a marked synergistic increase in DNA synthesis. This was also the case when 1 μg bFGF/l was used, but at a concentration of 25 pg bFGF/l synergy was only seen with IGF-I and TGF-β1. These results suggest that both basic and acidic FGF are potentially important regulators of adipocyte hyperplasia and that their effect is modulated by constituents of the extracellular matrix and the presence of other growth factors.
Journal of Endocrinology (1993) 137, 369–374
β-Cell tropin- and glucose-induced hypersecretion of insulin and amylin from perfused fatty rat pancreas
Authors: Dunmore S. J. , Cawthorne M. A. , Hislop D. C. J. , Morton J. L. , Beloff-Chain A. 
Published: December 2008

ABSTRACT
The neurointermediate pituitary peptide β-cell tropin (BCT) has potent insulin-releasing and lipogenic properties and is elevated in obesity and type-2 diabetes. The effects of BCT and glucose on the release of insulin and amylin from the perfused pancreas of obese 'fatty' (fa/fa) rats and lean (Fa/?) controls were measured. Pancreata were perfused, sequentially, with buffer containing: 5·6 mmol glucose/l (basal); basal glucose±0·5 nmol BCT/l; 16·7 mmol glucose/l (high). Insulin and amylin release during basal glucose treatment was eight to nine times greater from pancreata from fatty than from lean rats. BCT induced a fivefold greater monophasic insulin and amylin release from fatty compared with lean pancreata. When not preceded by BCT there was a twofold greater high glucose-induced amylin release from fatty pancreata but no difference in insulin secretion. When preceded by BCT stimulation, high glucose induced twofold greater insulin and fourfold larger amylin release from fatty compared with lean pancreata. Molar secretion ratios of insulin: amylin varied between 30:1 and 50:1. In view of the elevated levels of BCT found in the fatty rat and in the light of the above findings, it is concluded that the peptide may have a role in the development of hyperinsulinaemia, hyperamylinaemia and insulin resistance in this animal model of obesity and diabetes.
Journal of Endocrinology (1993) 137, 375–381
In-vitro effects of mammalian and amphibian prolactins on hepatic vitellogenin synthesis in Rana esculenta
Authors: Carnevali O. , Mosconi G. , Yamamoto K. , Kobayashi T. , Kikuyama S. , Polzonetti-Magni A. M. 
Published: December 2008

ABSTRACT
Male and female Rana esculenta liver was induced in an in-vitro system by homologous and Rana catesbeiana pituitary to synthesize and release vitellogenin, a lipoglycophosphoprotein precursor of yolk proteins, lipovitellins and phosvitins, in oviparous vertebrates.
In the present experiments, the action of prolactin on hepatic vitellogenin synthesis and release was investigated, using ovine prolactin and Rana catesbeiana prolactin. The effects of prolactin on hepatic vitellogenin synthesis displayed different trends related to sex; male liver was found to be more responsive than female liver to both ovine and frog prolactin; moreover, the response to prolactin was dose-related (r = 0·998; P <0·05) in male but not in female liver. In both sexes, a high degree of seasonality in the responsiveness of the liver was found, since the vitellogenin levels induced by prolactin during the winter phase were significantly (P < 0·001) higher than those produced during the summer phase. Thus, there was no significant difference between the action of ovine and frog prolactin on vitellogenin synthesis; in fact, mammalian prolactins are structurally similar with regard to nucleotide and amino acid sequences.
The direct action of prolactin on hepatic vitellogenin synthesis in the frog Rana esculenta is discussed, on the basis of the role played by prolactin as an important growth modulatory hormone in fetal and adult tissues.
Journal of Endocrinology (1993) 137, 383–389
Insulin-like growth factor-I-stimulated glucose transport in myotubes derived from chicken muscle satellite cells
Authors: Duclos M. J. , Chevalier B. , Le Marchand-Brustel Y. , Tanti J. F. , Goddard C. , Simon J. 
Published: December 2008

ABSTRACT
The effects of insulin and insulin-like growth factor-I (IGF-I) on glucose transport were compared in myotubes derived from chicken breast muscle satellite cells in vitro. Myotubes were incubated (for 0·5 or 4 h) with or without glucose in the presence or absence of insulin or IGF-I. Glucose uptake was subsequently measured by the incorporation of 2-[1,2-3H(N)] deoxy-d-glucose ([3H]2DG) in glucose-free medium (10 min at 20 °C). Glucose uptake was almost completely abolished by the addition of cytochalasin B or phloretin. It was increased by a decrease in glucose concentration in the incubation medium. Insulin (5 mg/l) stimulated [3H]2DG uptake to a maximum of 43 ± 10% above basal after 30-min incubation and 101 ± 15% after 4-h incubation. IGF-I and insulin at equimolar concentrations (25 μg/l and 20 μg/l respectively) were almost equipotent after 0·5 h but after 4-h incubation IGF-I was 17-fold more potent, suggesting that this 'late' effect was mediated through the IGF-I receptor. Incubation with cycloheximide suggested that the effect of IGF-I involved increased protein synthesis. The results suggest that chicken myotubes express a glucose transporter which is regulated by IGF-I and glucose concentration. However, they do not appear to express a typical insulin-responsive transport system.
Journal of Endocrinology (1993) 137, 465–472
Effect of altering endogenous gonadotrophin concentrations on the kinetics of testicular germ cell turnover in the bonnet monkey (Macaca radiata)
Authors: Aravindan G. R. , Gopalakrishnan K. , Ravindranath N. , Moudgal N. R. 
Published: December 2008

ABSTRACT
The role of FSH and diurnal testosterone rhythms in specific germ cell transformations during spermatogenesis were investigated using DNA flow cytometry and morphometry of the seminiferous epithelium of the adult male bonnet monkey (Macaca radiata), the endogenous hormone levels of which were altered by two different protocols. (1) Active immunization of five monkeys for 290 days using ovine FSH adsorbed on Alhydrogel resulted in the neutralization of endogenous FSH, leaving the LH and diurnal testosterone rhythms normal. (2) Desensitization of the pituitary gonadotrophs of ten monkeys by chronically infusing gonadotrophin-releasing hormone analogue, buserelin (50 μg/day release rate), via an Alzet pump implant (s.c.) led to a 60–80% reduction in LH and FSH as well as total abolition of testosterone rhythms. The basal testosterone level (3·3±2·0 μg/l), however, was maintained in this group by way of an s.c. testosterone silicone elastomer implant. Both of the treatments caused significant (P <0·01) nearly identical reduction in testicular biopsy scores, mitotic indices and daily sperm production rates compared with respective controls. The germ cell DNA flow cytometric profiles of the two treatment groups, however, were fundamentally different from each other. The pituitary-desensitized group exhibited a significant (P <0·001) increase in 2C (spermatogonial) and decrease in 1C (round spermatid) populations while S-phase (preleptotene spermatocytes) and 4C (primary spermatocytes) populations were normal, indicating an arrest in meiosis caused presumably by the lack of increment in nocturnal serum testosterone.
In contrast, in the FSH-immunized group, at day 80 when the FSH deprivation was total, the primary block appeared to be at the conversion of spermatogonia (2C) to cells in S-phase and primary spermatocytes (4C reduced by >90%). In addition, at this time, although the round spermatid (1C) population was reduced by 65% (P <0·01) the elongate spermatid (HC) population showed an increase of 52% (P <0·05). This, taken together with the fact that sperm output in the ejaculate is reduced by 80%, suggests a blockade in spermiogenesis and spermiation. Administration of booster injections of oFSH at time-points at which the antibody titre was markedly low (at days 84 and 180) resulted in a transient resurgence in spermatogenesis (at day 180 and 228), and this again was blocked by day 290 when the FSH antibody titre increased. Although in the two treatment groups overall spermatogenesis, as indicated by 1C:2C ratios, was significantly (P <0·01) reduced, the mechanisms by which this was brought about appeared to be different, suggesting that lack of FSH and testosterone (in particular the nocturnal testosterone surge) affect germ cell transformation at different foci.
Journal of Endocrinology (1993) 137, 485–495
Levels of insulin-like growth factor-binding protein-1 increase rapidly in amniotic fluid from 1 1 to 16 weeks of pregnancy
Authors: Wathen N.C. , Egembah S. , Campbell D.J. , Farkas A. , Chard T. 
Published: December 2008

ABSTRACT
Concentrations of IGF-binding protein-1 (IGFBP-1) were measured by radioimmunassay in 176 amniotic fluid samples from 9 to 20 and 36 to 42 weeks of pregnancy. Low levels of IGFBP-1 were present at 9 and 10 weeks (median values 35.0 and 45.0 μg/l respectively). After 10 weeks, the levels increased by four orders of magnitude to reach a peak at 16 weeks (median 145.2 mg/l). After 16 weeks levels fell. Near term, the levels (median 27.1 mg/l) were lower than in the second trimester. The rapid increase in IGFBP-1 shown by radioimmunoassay was confirmed by Western ligand blotting. The findings suggest that the regulatory role of IGFBP-1 in the growth or differentiation of the fetus or of its surrounding membranes may change as pregnancy advances.
The involvement of insulin-like growth factor-I in local control of steroidogenesis and DNA synthesis of Leydig and non-Leydig cells in the rat testicular interstitium
Authors: Moore A. , Morris I. D. 
Published: December 2008

ABSTRACT
Insulin-like growth factor-I (IGF-I) peptide, receptors and binding proteins are present in the rodent testis, which strongly implies that IGF-I has one or more testicular functions. In the present study we provide further information to support the concept that IGF-I is an important local mediator in the testis. High concentrations of IGF-I were measurable in interstitial fluid by radioimmunoassay, and IGF-I-binding proteins (IGFBPs) were readily detectable in interstitial fluid by ligand blotting, the predominant type being IGFBP-2. In vitro, IGF-I bound to testicular interstitial cells which did not have 3β-hydroxysteroid dehydrogenase (3β-HSD) activity and which were resistant to ethane dimethanesulphonate treatment. In vitro, IGF-I receptor-mediated actions increased both steroidogenesis and DNA synthesis. Insulin stimulated DNA synthesis at concentrations appropriate to cross-react with the IGF-I receptor, and this effect was greater in a testicular interstitial Leydig cell-depleted cell population compared with a Leydig cell-enriched cell culture. Furthermore, combinations of epidermal growth factor or transforming growth factor -α together with insulin appeared to act synergistically, causing extremely large increases in [3 H]thymidine incorporation in the interstitial cells. These results support a paracrine and/or autocrine role for IGF-I in interstitial cell growth and development.
Journal of Endocrinology (1993) 138, 107–114
Plasma measurements of corticotrophin-releasing hormone-binding protein in normal and abnormal human pregnancy
Authors: Perkins A. V. , Eben F. , Wolfe C. D. A. , Schulte H. M. , Linton E. A. 
Published: December 2008

ABSTRACT
Using corticotrophin-releasing hormone-binding protein (CRHBP) purified from human plasma and a 25 amino acid peptide corresponding to the C-terminus of CRHBP we have been able to produce rabbit polyclonal antisera specific for CRHBP. This has allowed the development of a radioimmunoassay which is able to detect CRHBP specifically in human plasma regardless of the presence of endogenous CRH. We have used this assay to estimate the level of CRHBP in non-pregnant human plasma to be approximately 20 nmol/l with a range of 9·1–40·6 nmol/l. We have also examined sequential plasma samples taken from 84 normal pregnant women at fortnightly intervals from 16 weeks gestation through to term. Four women were also sampled during labour and the first week postpartum. The median plasma level of CRHBP at week 16 of normal pregnancy was 21·59 nmol/l, levels rose slightly during the early part of the third trimester (26·76 nmol/l at week 30, (P < 0·01) and fell markedly towards term (19·72 nmol/l, P < 0·01) with only 8·70 nmol/l at labour. CRHBP levels returned to normal non-pregnant levels within 48 h of parturition suggesting a role for the fetoplacental unit in CRHBP production. In eight pregnancies complicated by diabetes, CRHBP levels at each gestational age were similar to those recorded for normal pregnancy. However, in pregnancies complicated by pre-term labour (n = 9) and pre-eclampsia (n = 7), plasma CRHBP levels were significantly reduced (P < 0·01).
Journal of Endocrinology (1993) 138, 149–157
Effects of consumption of milk and milk constituents on plasma concentrations of gastric inhibitory polypeptide and metabolites in preruminant goat kids
Authors: Martin P. A. , Faulkner A. , McCarthy J. P. 
Published: December 2008

ABSTRACT
Plasma concentrations of gastric inhibitory polypeptide (GIP) were measured in preruminant goat kids before and after consumption of milk, skimmed milk or solutions of milk fat, lactose, glucose or casein plus lactose. GIP concentrations increased significantly within 1 h of consumption of milk or milk fat, and were elevated for the remainder of the 5-h sampling period. The integrated mean change in GIP concentration during this period did not differ between these two meals. GIP levels were slightly increased above basal values 5 h after skimmed milk consumption, probably reflecting the absorption of a small amount of fat, but overall there was no significant GIP response to this or to any of the other test meals. The marked increase in GIP concentration after a milk feed indicates a physiological role for the hormone in preruminants but, in contrast to the situation in simple-stomached animals, carbohydrate absorption does not elicit GIP secretion in the preruminant goat. The data strongly suggest that fat is the major nutrient to stimulate GIP secretion in these animals.
Journal of Endocrinology (1993) 138, 167–173
Receptors for insulin-like growth factor-II in the growing tip of the deer antler
Authors: Elliott J. L. , Oldham J. M. , Ambler G. R. , Molan P. C. , Spencer G. S. G. , Hodgkinson S. C. , Breier B. H. , Gluckman P. D. , Suttie J. M. , Bass J. J. 
Published: December 2008

ABSTRACT
Insulin-like growth factor-II (IGF-II) binding in the growing tip of the deer antler was examined using autoradiographical studies, radioreceptor assays and affinity cross-linking studies. Antler tips from red deer stags were removed 60 days after the commencement of growth, and cryogenically cut into sections. Sections were incubated with radiolabelled IGF-II, with or without an excess of competing unlabelled IGF-II and analysed autoradiographically. Radiolabelled IGF-II showed high specific binding in the reserve mesenchyme and perichondrium zones, which are tissues undergoing rapid differentiation and cell division in the antler. Binding to all other structural zones was low and significantly (P<0·001) less than binding to the reserve mesenchyme/perichondrium zones. Radioreceptor assays on antler microsomal membrane preparations revealed that the IGF-II binding was to a relatively homogeneous receptor population (Kd= 1·3 × 10−10 mol/l) with characteristics that were not entirely consistent with those normally attributed to the type 2 IGF receptor. Tracer binding was partly displaceable by IGF-I and insulin at concentrations above 10 nmol/l. However, affinity cross-linking studies revealed a single band migrating at 220 kDa under non-reducing conditions, indicative of the type 2 IGF receptor. These results indicate that, in antler tip tissues, IGF-II binds to sites which have different binding patterns and properties from receptors binding IGF-I. This may have functional significance as it appears that, whilst IGF-I has a role in matrix development of cartilage, IGF-II may have a role in the most rapidly differentiating and proliferating tissues of the antler.
Journal of Endocrinology (1993) 138, 233–241