bluuebunny/crossref_metadata_2025_split huggingface dataset:
The International Reference Reagent for Insulin-like Growth Factor-I
Authors: Bristow A. F. , Gooding R. P. , Gaines Das R. E. 
Published: December 2008

ABSTRACT
Three preparations of recombinant DNA-derived insulin-like growth factor-I (IGF-I) were obtained, prepared in ampoules coded 86/522, 86/720 or 87/518, and evaluated as candidate International Reference Reagents in an international collaborative study (nine laboratories in four countries) in response to a request by the World Health Organization (WHO).
Immunoassay dose–response curves for each of the three preparations did not in general differ significantly from those of local standards or from those of ampouled preparations of serum-derived IGF-I which were included in the study. The estimates of ampoule contents in terms of local standards showed considerable heterogeneity; the between-laboratory variability of estimates in terms of local standards was ten times greater than the inherent variability of estimates from these systems as estimated from comparisons of coded duplicates. Bioassay data were limited, and those available were inconsistent with immunoassay data. Of the three preparations, ampoules coded 86/720 were derived from an IGF-I preparation that was heterogeneous by high-performance liquid chromatography, and stability data for the preparation 86/522 were anomalous.
As a result, the ampouled preparation coded 87/518 has been established by WHO as the International Reference Reagent for IGF-I for immunoassay, with an assigned ampoule content of 3·1 μg/ampoule, and is available from the National Institute for Biological Standards and Control.
Journal of Endocrinology (1990) 125, 191–197
Pituitary-testicular function is suppressed by an LHRH antagonist but not by an LHRH agonist in the marmoset monkey
Authors: Lunn S. F. , Dixson A. F. , Sandow J. , Fraser H. M. 
Published: December 2008

ABSTRACT
The use of pituitary desensitization by an LHRH agonist (buserelin) to examine pituitary-testicular function was investigated in a New World primate. Six adult male marmoset monkeys were injected s.c. with an LHRH agonist implant (1·5 mg in a rod 0·5 cm long). Pharmacokinetics, determined by radioimmunoassay of urinary buserelin, revealed a rapid initial release of the agonist followed by a steady decline during a 200-day period. The LHRH agonist treatment resulted in a rapid initial rise in plasma LH followed by a return to mean values similar to those seen in the control samples by 7 days after implantation. Using the present protocol, no evidence of subsequent pituitary desensitization or suppression of testicular function was observed, plasma concentrations of LH and testosterone remaining within the normal range during the 200-day study period.
In contrast, pituitary-testicular function was suppressed in the male marmoset after blockade of pituitary LHRH receptors by an LHRH antagonist. Five adults were treated with a single s.c. injection of the antagonist [Ac-d-Nal(2)1,d-pCl-Phe2,d-Trp3,d-Ser(Rha)6,AzGlyNH210]-LHRH at a dose of 300 μg/kg. The LHRH antagonist induced a marked suppression of plasma LH and testosterone by 6–8 h, the low levels being maintained for 24–48 h.
These results show that, whereas treatment with an LHRH antagonist can inhibit pituitary-testicular function in the male marmoset, it may be that desensitization cannot be induced by the LHRH agonist used.
Journal of Endocrinology (1990) 125, 233–239
Effects of corticostatin-I on rat adrenal cells in vitro
Authors: Tominaga T. , Fukata J. , Naito Y. , Nakai Y. , Funakoshi S. , Fujii N. , Imura H. 
Published: December 2008

ABSTRACT
We have examined the mechanism by which corticostatin-I (CS-I) acts to attenuate ACTH-induced steroidogenesis in rat adrenal cells. CS-I inhibited ACTH-induced corticosterone production in a dosedependent manner, without any effects on the basal corticosterone level in adrenal cells. When the cells were stimulated by 100 pg ACTH/ml, the minimum effective concentration of CS-I was 100 ng/ml, and 0.3–1.0 μg CS-I/ml produced a 50% reduction of the stimulated corticosterone production. The inhibitory effect of CS-I on ACTH-stimulated corticosterone production became apparent within 15 min of incubation, and the effect was reversed quickly by the removal of CS-I from the media. CS-I had no effect on angiotensin II-stimulated aldosterone production by adrenal zona glomerulosa cells. CS-I also did not affect cyclic AMP- or forskolin-stimulated corticosterone production. In an in-vitro binding study using 125I-labelled CS-I, CS-I showed considerable specific binding to rat adrenal cells, and the binding competed with ACTH in a dose-dependent manner. These experiments suggest that CS-I competes with ACTH on their binding sites and exerts an inhibitory effect on the adrenal cells.
Journal of Endocrinology (1990) 125, 287–292
Interaction of angiotensin II with the cholinergic and noradrenergic systems in the rat pineal gland: regulation of indole metabolism
Authors: Finocchiaro L. M. E. , Goldstein D. J. , Finkielman S. , Nahmod V. E. 
Published: December 2008

ABSTRACT
The pineal gland, angiotensin, and noradrenergic and cholinergic systems are involved in the regulation of tissue indole metabolism. Angiotensin II increased noradrenaline release and the production of hydroxy-and methoxyindoles by pineal slices. Electrical field stimulation (EFS) of pineal slices released angiotensin II and reproduced many of the actions of exogenous angiotensin II on serotonin and melatonin biosynthesis and release. Both sarcosine1-isoleucine8-angiotensin II ([Sar1,Ile8]-ANG II) and atropine blocked, and nadolol increased, the effect of EFS and exogenous angiotensin II on serotonin production. Nadolol blocked both the EFS-induced and the angiotensin II-induced production of melatonin. Atropine and [Sar1,Ile8]-ANG II did not modify melatonin biosynthesis in electrically stimulated slices, but the muscarinic receptor antagonist increased the stimulatory effect of angiotensin II. These data showed that EFS released angiotensin II and noradrenaline from pineal slices and that a close functional connection exists between the peptide and acetylcholine. The stimulation of serotonin biosynthesis and release by these two neurotransmitters was negatively regulated by noradrenaline acting through β-adrenergic receptors.
Journal of Endocrinology (1990) 126, 59–66
Central action of thyrotrophin-releasing hormone on growth hormone secretion in domestic fowl
Authors: Harvey S. , Lea R. W. , Ahene C. 
Published: December 2008

ABSTRACT
Peripheral plasma concentrations of GH in adult chickens were increased, in a dose-related manner, between 5 and 30 min after the intracerebroventricular (i.c.v.) injection of 0·1 or 10 μg TRH. In contrast, i.v. administration of comparable doses of TRH had no significant effect on circulating GH concentrations. [3H]3-methyl-histidine2-TRH ([3H]Me-TRH) was located in the pituitary gland and peripheral plasma within 5 min of its i.c.v. administration, although in amounts that were unlikely to affect directly pituitary function. [3H]Me-TRH rapidly accumulated in the hypothalamus following its i.c.v. administration (but not after i.v. injection), and the central effect of TRH on GH secretion in birds is therefore likely to be induced by effects at hypothalamic sites.
Journal of Endocrinology (1990) 126, 83–88
Effects of hyper- and hypothyroidism on carbonic anhydrase, Mg2+-dependent ATPase and Mg2+-dependent, HCO3−-stimulated ATPase activities of rat duodenal mucosa and kidney cortex
Authors: Suzuki S. , Chen H. , Takahashi T. , Niwa O. 
Published: December 2008

ABSTRACT
Carbonic anhydrase (CA) and Mg2+-dependent ATPase and Mg2+-dependent, HCO3−-dependent ATPase (Mg2+-HCO3−-ATPase) activities in rat duodenal mucosa and kidney cortex were examined with respect to thyroidal status. Administration of 50 and 150 μg thyroxine (T4)/kg per day s.c. for 7 days decreased duodenal cytosol CA activity to 66% of control with the former and 43% with the latter dose, while Mg2+-HCO3−-ATPase activity in brush borders of duodenal mucosa was increased to 116% of control by 150 μg T4/kg. CA and Mg2+-HCO3−-ATPase activities in the cytosol and brush border of kidney cortex did not change after administration of T4. Hypothyroidism induced by thyroidectomy for 2 and 4 weeks or administration of methimazole (2·5–20 mg/kg per day s.c. or peroral) for 2, 3 and 4 weeks all increased duodenal cytosol CA activity, to about 140% at 2 weeks and 153% at 4 weeks after thyroidectomy, and to about 136% after the oral administration of 10 mg methimazole/kg per day for 4 weeks, while brush border Mg2+-HCO3−-ATPase activity was decreased to 56% of control 4 weeks after thyroidectomy and to 74% after the s.c. administration of 20 mg methimazole/kg per day for 3 weeks. The increase in CA activity and the decrease in ATPase activity after thyroidectomy were restored to normal levels by replacement with T4. Neither enzyme activity in the kidney changed in hypothyroidism. Serum concentrations of T4 and cortisol-like material increased after administration of T4, and serum concentrations of T4, aldosterone and cortisol-like material all decreased in hypothyroidism. Correlations were observed between duodenal CA and Mg2+-HCO3−-ATPase activities and serum concentrations of T4 (P < 0·01). These results reveal that the decrease in CA activity and the increase in Mg2+-HCO3−-ATPase activity of duodenal mucosa in hyperthyroidism are reversed in hypothyroidism, while both enzyme activities in the kidney are unrelated to thyroidal status.
Journal of Endocrinology (1990) 126, 119–129
Effects of a novel 21-amino steroid, U74006F, on the rat pituitary-adrenocortical axis
Authors: Burrin J. M. , Hart G. R. 
Published: December 2008

ABSTRACT
The 21-amino steroid U74006F is a potent inhibitor of lipid peroxidation and has been shown to affect beneficially the acutely injured central nervous system. Therapeutically, it is desirable for this compound to be devoid of steroid side-effects. We have demonstrated a significant (P < 0·001) inhibition of basal ACTH secretion from cultured rat pituitary cells during a 24-h incubation at concentrations (10–100 μmol/l) previously demonstrated to inhibit lipid peroxidation in vitro. U74006F also inhibited corticotrophin-releasing factor (CRF)-stimulated ACTH secretion significantly and the combination of dexamethasone and U74006F completely blocked CRF-41-stimulated ACTH secretion. Administration of U74006F in vivo (30 mg/kg, orally, every 6 h for 30 h) had no effect on ACTH levels in normal rats (84±38 vs 45±6 ng/l in control animals) but increased ACTH levels in adrenalectomized rats (1330±295 vs 464±79 ng/l in control animals, P < 0·02). This increase in ACTH was not observed when adrenalectomized animals were maintained on the same regime of U74006F for 5 days. Our data suggest that U74006F is capable of exerting inhibitory effects on ACTH secretion in vitro. In vivo, effects on ACTH secretion were stimulatory rather than inhibitory and only occurred short-term in adrenalectomized animals or chronically in adrenalectomized rats maintained on dexamethasone. No effects on the pituitary-adrenocortical axis were seen following short-term or chronic administration of U74006F in normal rats.
Journal of Endocrinology (1990) 126, 203–209
Chronic regulation of ovarian oxytocin and progesterone release by prostaglandins: opposite effects in bovine granulosa and early luteal cells
Authors: McArdle C. A. 
Published: December 2008

ABSTRACT
Oxytocin is synthesized in the granulosa-derived large cells of the ruminant corpus luteum from a gene which is dramatically up-regulated in the first few days after ovulation. In this work, the regulation of granulosa and luteal cells by prostaglandins and insulin (or insulin-like growth factor-I; IGF-I) has been explored by comparing their effects on oxytocin and progesterone production in cell culture. In granulosa cells, chronic exposure to insulin (17 nmol/l) stimulated luteinization as indicated by increased release of oxytocin and progesterone. Prostaglandin F2α (PGF2α) alone had little effect, but synergized with insulin (or IGF-I) to increase the release of both these hormones. In direct contrast, insulin-stimulated oxytocin production by luteal cells was inhibited by PGF2α. The half-maximal dose (EC50) for PGF2α action in both cell preparations was similar (10–100 nmol/l). Dose–response studies revealed that PGF2α increased the potency of insulin in granulosa cells (EC50 for insulin-stimulation of oxytocin release reduced from 141 to 13 nmol/l by 1 μmol PGF2α/l), but not in luteal cells. Insulin-stimulated oxytocin release from granulosa cells was also synergistically increased by PGE1, PGE2 and forskolin, suggesting this effect to be mediated by adenylate cyclase-coupled PGE receptors. The results reveal that the effects of prostaglandins on oxytocin release are dependent on both the developmental stage of the target tissue and on the presence of other regulators of cellular differentiation. Moreover, they suggest that the increase in responsiveness to insulin and IGF-I, which appears to accompany luteinization in the cow, may be an effect of prostaglandins produced locally during the peri-ovulatory period.
Journal of Endocrinology (1990) 126, 245–253
Effects of the synthetic glucocorticoid dexamethasone on reproductive function in the ewe
Authors: Phillips D. J. , Clarke I. J. 
Published: December 2008

ABSTRACT
Glucocorticoids have been found to inhibit reproductive function in most domestic species studied but, in the ewe, preliminary reports suggest that glucocorticoids may have little or no effect. This study investigated the effects of the synthetic glucocorticoid dexamethasone on oestrus and ovulation rate in ewes during the breeding season and gonadotrophin secretion in the breeding and non-breeding seasons. In cyclic ewes, dexamethasone treatment at rates of up to 2 mg/day did not affect the natural or pregnant mare serum gonadotrophin-stimulated ovulation rate, or the timing and incidence of behavioural oestrus (P>0·05). Dexamethasone administration (2 mg/day) had no effect on LH secretion or the plasma LH response to a 1 μg injection of gonadotrophin-releasing hormone (GnRH) in ovariectomized ewes in the breeding and non-breeding seasons, and did not compromise the inhibition of plasma LH levels during chronic treatment with oestrogen. Similarly, dexamethasone had no effect on plasma FSH concentrations, but significantly (P<0·05) reduced the plasma FSH response to a 1 μg GnRH injection during chronic negative treatment with oestrogen in ovariectomized ewes. Collectively, these data show that in these experiments dexamethasone did not significantly modify reproductive function in the ewe, a finding that is in contrast to that found in other domestic species.
Journal of Endocrinology (1990) 126, 289–295
Inhibition of the pituitary-gonadal axis in nude male mice by continuous administration of LHRH agonists and antagonists
Authors: Redding T. W. , Schally A. V. 
Published: December 2008

ABSTRACT
Analogues of LHRH can be used for the treatment of sex hormone-dependent tumours. The nude mouse is a valuable model for the investigation of transplanted human cancers, but there is a body of literature reporting that the function of the pituitary-gonadal axis in normal (immunocompetent) and nude (immunocompromized) mice, unlike that of other species, cannot be suppressed by the administration of LHRH agonists and antagonists. To explore this view further, long-term experiments were carried out in nude male mice, in which sustained-release formulations of the agonist [d-Trp6]-LHRH and of two new potent antagonists were used which permitted a continuous release of the peptides into the circulation. Nude male mice were treated for 28-30 days with 50 μg of antagonists [Ac-d-Nal(2)1,d-Phe(4Cl)2,d-Trp3,d-Cit6,d-Ala10]-LHRH (SB-30) or [Ac-d-Nal(2)1,d-Phe(4Cl)2,d-Pal(3)3,d-Cit6,d-Ala10]-LHRH (SB-75)/day delivered by osmotic minipumps. Some mice were injected twice a day with 25 μg SB-75. Other groups received microcapsule preparations of the agonist [d-Trp6]-LHRH, releasing 25 or 12·5 μg/day for 30 days. At autopsy, in mice which received 50 μg SB-30 or SB-75/day by minipumps, there was a significant decrease in weights of testes, ventral prostate and seminal vesicles compared with controls. [d-Trp6]-LHRH microcapsules at either dose also reduced weights of testes and accessory sex organs. Serum LH and testosterone were significantly reduced in all groups treated with analogues. There was a greater decrease in testicular weights and serum testosterone in nude mice which received SB-75 in a continuous fashion from minipumps than in animals injected twice a day. These results clearly demonstrate, contrary to the existing data, that the pituitary-gonadal axis of nude mice can be inhibited by LHRH agonists or antagonists if they are administered by continuous release systems. This study indicates that when the sustained-release formulations are used, nude mice can be valuable for studying the effects of analogues of LHRH on tumour biology
Journal of Endocrinology (1990) 126, 309–315
Effects of hypophysectomy and human chorionic gonadotrophin on Leydig cell function in mature rats
Authors: Stocco D. M. , Teerds K. J. , van Noort M. , Rommerts F. F. G. 
Published: December 2008

ABSTRACT
The biochemical activities involved in the maintenance of Leydig cell functions, and the effects of hypophysectomy and human chorionic gonadotrophin (hCG) on these functions are largely unknown. In the present study, adult hypophysectomized rats were used as a model to determine the effects of these treatments on a number of biochemical and morphological parameters. After 33 days of hypophysectomy, the morphology of the Leydig cells had been drastically altered. In addition, α-naphthol and β-naphthol esterase activity as well as the steroidogenic capacity of the Leydig cells were greatly reduced at this time. In contrast, the level of sterol carrier protein 2 (SCP2), a Leydig cell-specific protein, was affected by hypophysectomy much less than the other parameters measured. Two daily injections of hCG to rats hypophysectomized for 31 days resulted in no change in the morphology of the Leydig cells, or in their proliferative activity. Non-specific esterase activities were also unaffected by 2 days of treatment with hCG. However, two injections of hCG to rats hypophysectomized for 31 days resulted in nearly complete restoration of steroidogenic capacity, and a 3·5-fold increase in the level of SCP2. These findings indicate that hypophysectomy results in significant morphological and biochemical changes in Leydig cells, and that hCG is capable of restoring some of these capacities within a short time.
Journal of Endocrinology (1990) 126, 367–375
Nuclear tri-iodothyronine (T3) binding in neonatal rat brain suggests a direct glial requirement for T3 during development
Authors: Hubank M. , Sinha A. K. , Gullo D. , Ekins R. P. 
Published: December 2008

ABSTRACT
Tri-iodothyronine (T3) binding studies were performed on neuronal and glial nuclei prepared from developing rats brain by discontinuous sucrose gradient centrifugation. Maximum binding capacities (MBC) and dissociation constants (Kd) were obtained from Eadie-Hofstee plots of transformed data. An ontogenic study on nuclei prepared from whole brain revealed that on day 5 after birth, glial nuclear MBC was 1774±201 (s.e.m.) fmol/mg DNA compared with 974±117 fmol/mg DNA for the neurones (P<0·01). Although diminishing to 667±112 fmol/mg DNA by day 21, alterations in neuronal MBC over the neonatal period were not statistically significant, whereas glial MBC diminished steadily to 557±133 fmol/mg DNA in glial nuclei (P<0·05). Over the same period, a significant reduction in Kd was noted only in the glia, from 3·17±0·40 to 1·83±0·34 nmol/l (P<0·03). Ligand specificity of the receptor in both nuclear types on day 21 was tri-iodoacetic acid > T3 > thyroxine > 3,3′,5′-T3, but this was less clearly demonstrated at day 5.
Regional studies on days 15 and 21 demonstrated that for both neuronal and glial nuclei, receptors are concentrated in the cerebral cortex and diminish in a cranio-caudal direction. Cerebral glial MBC on day 21 was 2215±147 fmol/mg DNA, at this stage still exceeding the cerebral neuronal capacity of 1111±207fmol/mg DNA. The results indicate that neonatal glia may respond directly to thyroid hormones via nuclear receptor binding, and that receptors are predominantly located in the cortex. Decreases in average MBC in the late neonate may be due to increases in the numbers of cells containing fewer nuclear receptors.
Journal of Endocrinology (1990) 126, 409–415
Ageing and the sensitivity of the adrenal gland to physiological doses of ACTH in man
Authors: Roberts N. A. , Barton R. N. , Horan M. A. 
Published: December 2008

ABSTRACT
Healthy men and women aged 19–38 or 67–83, in whom endogenous ACTH secretion was suppressed with dexamethasone, were given successive injections of 60 ng, 150 ng and 250 μg ACTH(1–24) at hourly intervals, and blood samples for measurement of plasma cortisol were taken every 10 min. The response to each injection was taken as the increase in cortisol concentration 20 min later, when there was a peak with the lower doses, with allowance for disappearance of cortisol produced after the previous injection. On average, the responses to 60 and 150 ng ACTH were about 0·4 and 0·7 respectively of the response to 250 μg. There were no consistent effects of age or sex on any index of adrenocortical sensitivity or responsiveness, but some groups showed isolated differences from both their age- and sex-matched counterparts: the response to 60 ng ACTH was low in young men, maximal responsiveness was low in elderly men and the slope of the dose–response curve was high in elderly women. In most of the elderly subjects, plasma ACTH was determined separately under normal conditions. It was negatively correlated with the cortisol responses to 60 and 150 ng ACTH, suggesting that differences in adrenal sensitivity between subjects contribute to the variability of plasma ACTH.
Journal of Endocrinology (1990) 126, 507–513