bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stimulatory effect of retinoic acid on GH gene expression: the interaction of retinoic acid and tri-iodothyronine in rat pituitary cells
Authors: Morita S. , Matsuo K. , Tsuruta M. , Leng S. , Yamashita S. , Izumi M. , Nagataki S. 
Published: December 2008

ABSTRACT
We have previously demonstrated that retinoic acid (RA) as well as thyroid hormone stimulates GH gene expression. To clarify the relationship between the action of RA and thyroid hormone, pituitary-specific gene expression was investigated further in rat pituitary cells.
Rat clonal pituitary cells, GH3, were treated with RA with or without tri-iodothyronine (T3) for up to 3 days. After treatment with 10–1000 nmol RA/1 with or without 0·1–10 nmol T3/1, medium was collected for radioimmunoassay and cells were subjected to RNA extraction, and GH and prolactin gene expression was analysed using 32P-labelled rat GH and rat prolactin cDNA probes respectively. The data demonstrated the dose–responsive manner of the stimulatory effects of RA and T3 on GH secretion with T3-depleted media. The action of RA was additive to that of T3 for GH secretion when maximum effective doses of RA or T3 were used. Using dot blot and Northern gel analysis, it was shown that RA increased GH mRNA levels in T3-depleted media, and that this action of RA was additive to that of T3 on the induction of GH mRNA levels. In contrast, neither RA nor T3 stimulated the secretion of prolactin and prolactin mRNA levels in these cells.
Our results indicate that RA stimulates GH mRNA increment and GH secretion in T3-depleted media, and that the stimulatory effect of RA is additive to the maximum effective dose of T3.
Journal of Endocrinology (1990) 125, 251–256
The presence of classical insulin-like growth factor (IGF) type-I and -II receptors on mouse osteoblasts: autocrine/paracrine growth effect of IGFs?
Authors: Slootweg M. C. , Hoogerbrugge C. M. , de Poorter T. L. , Duursma S. A. , van Buul-Offers S. C. 
Published: December 2008

ABSTRACT
Specific binding to and proliferative actions of insulinlike growth factors-I and -II (IGF-I and -II) on fetal mouse osteoblasts were tested. Membranes of mouse osteoblasts were shown by binding competition studies to possess specific binding sites for IGF-I and IGF-II. When IGF-I was used as a tracer, half-maximal displacement was obtained with 1·11 μg IGF-I/1 and with 14 μg IGF-II/1. Displacement of 125I-labelled IGF-I was accomplished with 2·33 μg IGF-II/1 and with 55 μg IGF-I/1. Affinity cross-linking showed bands of 130 kDa 125I-labelled IGF-I and 260 kDa 125I-labelled IGF-II under reducing conditions, further indicating the presence of classical type-I and -II receptor sites on mouse osteoblasts. Mitogenic effects of IGFs were weak; a combination with epidermal growth factor or fibroblast growth factor showed strong synergistic action however. The possibility of autocrine/paracrine actions of IGFs is discussed.
Journal of Endocrinology (1990) 125, 271-277
Involvement of the adrenal gland in the suckling-induced decrease in LH and FSH secretion and the concomitant increase in prolactin secretion in the rat
Authors: Taya K. , Sasamoto S. 
Published: December 2008

ABSTRACT
The role of the adrenal gland in the regulation of gonadotrophin and prolactin secretion in the lactating rat was investigated. Changes in secretion of LH, FSH, prolactin, ACTH, β-lipotrophin (β-LPH), inhibin, corticosterone and progesterone after adrenalectomy were examined during the second half of lactation. Follicular maturation was determined by the ability of the follicles to ovulate in response to 10IU human chorionic gonadotrophin (hCG). Adrenalectomy on day 10 of lactation prevented an increase in plasma concentrations of LH and FSH in response to ovariectomy performed at the same time as adrenalectomy, and markedly stimulated secretion of ACTH, β-LPH and prolactin. Adrenalectomy reduced the number of follicles capable of ovulating in response to hCG. Concentrations of inhibin and progesterone in the plasma significantly decreased after adrenalectomy, indicating that development of ovulatory follicles and luteal function had been suppressed. Abolishing the increase in plasma concentrations of LH and inducing a decrease in FSH in the plasma by adrenalectomy therefore prevented maturation of a new set of follicles usually seen during the second half of lactation in rats. The decrease in plasma concentrations of LH also inhibited the ability of the corpus luteum to secrete progesterone, although high concentrations of plasma prolactin were maintained in adrenalectomized lactating rats.
These results indicate that the pituitary-adrenal system is capable of influencing the maintenance of a normal secretion of gonadotrophin and prolactin as well as the maintenance of ovarian function during lactation in the rat.
Journal of Endocrinology (1990) 125, 279—285
Monoclonal antibodies against the free subunits of human chorionic gonadotrophin
Authors: Berger P. , Klieber R. , Panmoung W. , Madersbacher S. , Wolf H. , Wick G. 
Published: December 2008

ABSTRACT
Discordant results on body fluid levels of human chorionic gonadotrophin (hCG) free α- and β-subunits under physiological and pathophysiological conditions, prompted us to raise a total of 260 monoclonal antibodies (MCA) against free hCG-α, free hCG-β, holo-hCG, human follicle-stimulating hormone and bovine luteinizing hormone; 153 MCA recognizing the human α-subunit and 28 reacting with hCG-β were extensively analysed for their intra- and interspecies cross-reactivity with homologous hormones, and for the compatibility of epitopes recognized by them. The immunological topography of free hCG-α and free hCG-β was resolved by these MCA, and epitope maps were designed. Six antigenic determinants on the free α-chain (α1–α6), clustered in three spatially distinct domains, and seven epitopes on the surface of free hCG-β (β1–β7), could be distinguished. Strikingly, three α-chain epitopes (α4, α5 and α6) were shared between various species, which is in contradiction to the concept of immunological species-specificity of α-subunits. Three determinants were found to be present only on the free subunits but not on holo-hCG (α6, β6 and β7), and only two determinants (β1 and β7) were hormone-specific for hCG. Based on this information, an immunoenzymometric assay for the free α-subunit of human glycoprotein hormones was established, with a sensitivity of 1·3 pg/well and a cross-reactivity with holo-hCG of less than 0·005% Thus this assay provides the basis for detecting free α-subunits in the presence of extremely high levels of holo-hormones, which may assist in elucidating the role of free α-subunits in man.
Journal of Endocrinology (1990) 125, 301–309
Dose—response curves for treatment with biosynthetic human growth hormone
Authors: Darendeliler F. , Hindmarsh P. C. , Brook C. G. D. 
Published: December 2008

ABSTRACT
We have studied the effect of varying doses of biosynthetic human GH on the growth response over the first year of therapy in 90 short prepubertal children (67 males and 23 females, aged 3·1–12·9 years). As pretreatment height velocity was the predominant determinant of response, the children were divided into three groups on the basis of their pretreatment height velocity standard deviation scores (SDS). Group A (n=27) had pretreatment height velocity SDS between +1·3 and −0·8 (short normal growing children), group B (n=35) between −0·9 and −2·0 (moderate GH insufficiency) and group C (n=28) less than −2 (severe GH insufficiency). Within each group, the dose of GH administered was the dominant factor in the regression. At a mean dose of 16 units/m2 body surface area per week, the change in height velocity SDS over the first year of therapy was +2·9 (95% confidence interval (CI) 2·4, 3·5) in group A, +4·3 (95% CI 3·9, 4·6) in group B and +7·0 (95% CI 6·0, 8·0) in group C. These values translate into increases in growth rate of 2·2, 3·4 and 5·5 cm/year for an 8-year-old in each group respectively. These results have important implications in planning the treatment of children with GH insufficiency.
Journal of Endocrinology (1990) 125, 311–316
Secretion of ACTH by perifused isolated rat anterior pituitary cells: pulses of secretagogue enhance the secretory response and modify the effect of atriopeptin
Authors: Antoni F. A. , Dayanithi G. 
Published: December 2008

ABSTRACT
The aim of the present study was to characterize the inhibitory action of atriopeptin on secretagogue-evoked ACTH release in vitro.
Perifused isolated rat anterior pituitary cells were exposed to repeated pulses of 41-residue corticotrophin-releasing factor (CRF-41) or arginine vasopressin (AVP). The net ACTH secretory response to both neurohormones increased progressively with the number of pulses applied, until a maximum hormonal response was reached which was stable for the subsequent period of observation (2–3 h). The maximal secretagogue-evoked hormone release eventually achieved was 4 and 1·7 times greater than the initial response to AVP and CRF-41 respectively. The size of the ACTH response elicited by 50 pmol CRF-41/1 and 500 pmol AVP/1 (CRF/AVP) given together also underwent progressive enhancement. The number of secretagogue pulses required to reach the maximal response to a particular stimulus depended upon the concentration of the secretagogue peptides, higher concentrations favoured a more rapid development of the stable secretory response.
The potency of 103–126 residue atriopeptin to inhibit CRF/AVP-induced ACTH release varied by about 1000-fold depending upon the prior treatment of the cells. In general, cells not previously exposed to secretagogues appeared largely resistant, those under a moderate secretagogue drive were strongly inhibited, and those under intense stimulation were again refractory to inhibition by atriopeptin. In contrast, corticosterone suppressed stimulated ACTH release regardless of the state of the cells.
The data demonstrate that the conditions of cell maintenance are pivotal determinants of the inhibitory effect of atriopeptin on secretagogue-stimulated ACTH release in vitro. The in-vivo correlate of these findings may be that the sensitivity of corticotrophs towards atriopeptin is determined by requirements encoded through the pattern of release of hypothalamic CRF-41 and AVP.
Journal of Endocrinology (1990) 125, 365–373
Effects of gastric inhibitory polypeptide, vasoactive intestinal polypeptide and peptide histidine isoleucine on the secretion of hormones by isolated mouse pancreatic islets
Authors: Bailey C. J. , Wilkes L. C. , Conlon J. M. , Armstrong P. H. , Buchanan K. D. 
Published: December 2008

ABSTRACT
The release of insulin, glucagon, somatostatin and pancreatic polypeptide (PP) by isolated mouse pancreatic islets was determined during 30-min incubations at 5.6 and 16.7 mmol glucose/l in the absence and presence of gastric inhibitory polypeptide (GIP), vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI) at concentrations of 1–1000 nmol/l. Insulin release was enhanced (>50%) by GIP (100–1000 nmol/l) and VIP (1 μmol/l) at 5.6 mmol glucose/l, but not at 16.7 mmol glucose/l. Glucagon release was increased by GIP (100–1000 nmol/l), and by VIP and PHI (1—1000 nmol/l) at both glucose concentrations in a dose-related manner (maximum increases > tenfold). Somatostatin release was similarly increased by GIP (10–1000 nmol/l) at both glucose concentrations. Only the highest concentration (1 μmol/l of PHI tested increased somatostatin release (twofold) at 5.6 mmol glucose/l, whereas PHI and VIP (1–1000 nmol/l reduced (>37%) somatostatin release at 16.7 mmol glucose/l. PP release was increased (49–58%) by 100–1000 nmol GIP/l, but was not significantly altered by VIP, and was reduced (39–56%) by PHI. The results indicate that GIP, VIP and PHI each stimulate glucagon release in a dose-related manner, but they exert discretely different effects on other islet hormones depending upon the dose and the prevailing glucose concentration.
Journal of Endocrinology (1990) 125, 375–379
Effects of passively immunizing ewes against inhibin and oestradiol during the follicular phase of the oestrous cycle
Authors: Mann G. E. , Campbell B. K. , McNeilly A. S. , Baird D. T. 
Published: December 2008

ABSTRACT
Passive immunization was used to investigate the importance of inhibin and oestradiol in the control of FSH production during the follicular phase of the oestrous cycle in the sheep. Four groups of five mature Scottish Blackface ewes were injected with normal sheep plasma (control), antiserum to the 1–26α peptide fragment of porcine inhibin, antiserum to oestradiol-17β, or a combination of the two antisera, 24 h following cloprostenol-induced luteal regression. There was no difference in the concentration of LH in jugular venous plasma between the control and inhibin-immunized groups following the injection of normal sheep plasma or inhibin antiserum, with both groups exhibiting normal LH surges. In both the groups immunized against oestradiol, the basal concentration of LH rose by 25–30% (P<0.05) during the 96-h period following injection, while the LH surge and consequent formation of a corpus luteum was inhibited. In all three immunized groups there was a significant (P<0.001) rise in the concentration of FSH starting 3.8–4.8 h after the injection of antiserum. The duration of the rise was similar in the groups injected with oestradiol antiserum alone (43.6±12.8 h) or in combination with inhibin antiserum (40.6 ± 11.7 h), but was significantly (P<0.05) shorter in the group immunized against inhibin alone (17.0 ± 0.5 h). The rise in FSH was similar in the groups immunized against inhibin (142 ± 6%) or oestradiol (143±4%) alone, and was significantly (P<0.01) greater in the group injected with both antisera (195± 17%). These results provide evidence that both oestradiol and inhibin play a role in regulating the concentration of FSH during the follicular phase of the oestrous cycle, while reinforcing the hypothesis that inhibin is not involved in the regulation of LH production.
Journal of Endocrinology (1990) 125, 417–424
Serotonin enhances oestradiol production by hamster preovulatory follicles in vitro: effects of experimentally induced atresia
Authors: Terranova P. F. , Uilenbroek J. Th. J. , Saville L. , Horst D. , Nakamura Y. 
Published: December 2008

ABSTRACT
Preovulatory follicles from adult hamsters on the morning of pro-oestrus were used in this study. Serotonin stimulated oestradiol production by preovulatory follicles during a 5-h incubation in 1 ml Krebs–Ringer bicarbonate glucose medium containing isobutylmethylxanthine (0.1 mmol/l; IBMX) and androstenedione (1 μmol/l). The enhanced oestradiol production by serotonin was dependent on the dose of IBMX and androstenedione. Mianserin, a serotonin type-1 and serotonin type-2 receptor antagonists, prevented the serotonin-enhanced oestradiol production in a dose-dependent manner. Ketanserin, a specific serotonin type-2 receptor antagonist, was ineffective in blocking the action of serotonin, indicating that the effect of serotonin was mediated by the serotonin type-1 receptor. In the presence of androstenedione (1 μmol/l), serotonin was unable to enhance oestradiol production in isolated granulosa cells. It was also unable to enhance oestradiol production in early atretic follicles; atresia was induced experimentally by an injection of phenobarbital in order to prevent ovulation.
The data indicate that serotonin stimulates oestradiol production by hamster preovulatory follicles in vitro. The mechanism of action of serotonin involves an intact healthy follicle, a serotonin type-1 receptor and possibly cyclic AMP. The increased oestradiol secretion might be related to increased androgen production by the follicle and increased permeability (leakiness) of the follicle to androstenedione which serves as substrate for aromatization to oestradiol by the granulosa cell.
Journal of Endocrinology (1990) 125, 433–438
Human chorionic gonadotrophin-like and β-core-like materials in postmenopausal urine
Authors: Akar A. H. , Gervasi G. , Blacker C. , Wehmann R. E. , Blithe D. L. , Nisula B. C. 
Published: December 2008

ABSTRACT
In addition to human chorionic gonadotrophin (hCG), the urine of pregnant women contains a small molecular weight form of the hCG-β subunit known as β-core. Human CG-like material has been described in tissues, serum and urine of normal man, particularly in postmenopausal women. We examined different urine preparations from postmenopausal women to determine whether β-core-like material, as well as hCG-like material, could be detected. We studied an acetone extract of a pool of 11 litres of postmenopausal urine, three different commercial preparations of human menopausal gonadotrophins and two commercial preparations of 'pure' FSH. After Sephadex G-100 chromatography of these various postmenopausal urine extracts, fractions were assayed using four assay systems to detect hCG, β-core, LH and FSH immunoreactivities. Human CG immunoreactivity was readily detected in all urinary extracts and it eluted in a position indistinguishable from that of purified hCG. In addition to this hCG-like material, all urinary extracts, except the commercial 'pure' FSH preparations, contained material which reacted in the β-core radioimmunoassay. This β-core immunoreactive material eluted from Sephadex G-100 in a position corresponding to that of purified pregnancy-derived β-core. We conclude that the urine of postmenopausal women contains material resembling the β-core molecule found in pregnancy urine. The origin of this β-core-like material remains to be determined, and its presence will have an impact on the application of urinary β-core as a tumour marker.
Journal of Endocrinology (1990) 125, 477–484
Localization and characterization of epidermal growth factor receptors on human testicular tissue by biochemical and immunohistochemical techniques
Authors: Stubbs S. C. , Hargreave T. B. , Habib F. K. 
Published: December 2008

ABSTRACT
In the present study attempts were made to characterize the epidermal growth factor (EGF) receptor on human testicular tissue. A radioligand exchange assay with 125I-labelled EGF was used to detect a high affinity, low capacity, single binding site in the 105 000 g particulate fraction of human testicular tissue. Binding was optimal at 32 °C following a 40-min incubation with a mean ( ± s.d.) dissociation constant of 327 ±59 pmol/l (d.f. 9). The number of binding sites ranged from 0.07 to 0.21 pmol/mg protein. Competition studies with other peptide hormones including LH, FSH, prolactin, insulin-like growth factor-I, fibroblast growth factor and nerve growth factor have confirmed the specificity of EGF for its receptor. The receptor was also found to be heatlabile and sensitive to trypsinization. Cross-linking experiments using disuccinimidyl suberate revealed major binding species at the 125 kDa region and this is thought to represent a proteolysed form of the receptor. Immunohistochemical localization of the receptors demonstrated their presence in the interstitial tissue and not within the seminiferous tubules. The presence of specific EGF binding in the interstitial tissue suggests that EGF may play some role in testicular steroidogenesis.
Journal of Endocrinology (1990) 125, 485–492
Patterns of variation in progestin in pregnant sheep
Authors: Caton D. , Kalra P. S. 
Published: December 2008

ABSTRACT
Patterns of variation in progestin concentrations were studied in pregnant sheep during the last half of gestation. In three sets of experiments, blood was drawn daily or every 4 h for 24 h or every 10 min for 8 h. Peripheral arterial concentration of progestin was examined for 'peaks' using the Pulsar program which identified peaks in daily samples and in samples collected every 10 min, though less often than in daily samples. Ovariectomy did not affect the frequency or character of the peaks. The data suggest that large variations in progestin concentrations occur during the last half of pregnancy. They are superimposed on a gradual increase in average concentration and last for 2 to 3 days.
Journal of Endocrinology (1990) 126, 37–42
Increased in-vivo insulin sensitivity but normal liver insulin receptor kinase activity in dwarf chickens
Authors: Guéritault I. , Simon J. , Chevalier B. , Derouet M. , Tixier-Boichard M. , Mérat P. 
Published: December 2008

ABSTRACT
The effects of the recessive and sex-linked dw gene on insulin sensitivity and liver insulin receptors were compared in normal (Dw-dw) and dwarf (dw-dw) brother or half-brother chickens. At 3·5 weeks of age, following an overnight fast, exogenous insulin (0–6·9 nmol/kg body weight) was slightly but significantly more hypoglycaemic in dwarf chickens. At 4 weeks of age, following an oral glucose load (2 g/kg), glucose tolerance was the same in both genotypes, whereas plasma insulin levels were greatly decreased in dwarf chickens. At 5 weeks of age, plasma concentrations of glucose and insulin were the same in both genotypes in the fasting state and decreased in the fed state in dwarf chickens. In liver membranes prepared from fasted chickens, insulin binding was increased in dwarf chickens, while the affinity of insulin receptors and the insulin-degrading activity of the membranes were the same in both genotypes. Following solubilization with Triton X-100, liver receptors were successively purified on lentil then wheat germ lectins. Autophosphorylation of the β-subunit did not differ between either the genotype or the nutritional (fed or fasted) state. In the basal state (in the absence of insulin) the tyrosine kinase activity of the receptor towards artificial substrate poly(Glu,Tyr)4:1 was significantly decreased in dwarf chickens by fasting. However, the change in tyrosine kinase activity of the receptor in response to insulin was similar, irrespective of the genotype and the nutritional state. Therefore, the slight increase in insulin sensitivity observed in vivo in dwarf chickens is accounted for, at least partly, by a slight increase in liver insulin receptor number, but not by a change in the kinase activity of liver insulin receptors. In addition, post-insulin receptor kinase events and/or GH-dependent counter-regulatory mechanisms may superimpose and increase the insulin sensitivity of dwarf chickens.
Journal of Endocrinology (1990) 126, 67–74