bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of rearing rainbow trout on black or white backgrounds on their secretion of melanin-concentrating hormone and their sensitivity to stress
Authors: Green J. A. , Baker B. I. , Kawauchi H. 
Published: December 2008

ABSTRACT
Rainbow trout were reared in black or off-white coloured tanks for up to 18 months of age to achieve maximum differences in the synthesis of the neuropeptide, melanin-concentrating hormone (MCH). White-reared fish had greatly increased MCH concentrations in their pituitary glands, in their MCH perikarya and in the presumptive neuromodulatory fibres of the dorsal hypothalamus/thalamus when compared with black-reared and commercially reared trout. Following transfer to brighter white tanks, white-reared fish showed a significant increase in plasma MCH concentration and a reduction of MCH in the pituitary and MCH perikarya. The additional challenge of repeated stress further increased plasma MCH concentration in these fish and also reduced MCH in the dorsal hypothalamus/thalamus. In black-reared fish transferred to white tanks, plasma MCH concentrations were significantly raised after transfer, although they were lower after 11 days than in white-reared counterparts. Transfer from black to white background caused a fall in the MCH concentration in all regions— pituitary gland, perikarya and dorsal hypothalamus/thalamus; if transfer was accompanied by repeated stress, the hormone in the pituitary gland and MCH perikarya became so depleted that plasma MCH concentrations declined. Within each experimental situation (control, background transfer and transfer with stress) there was in inverse correlation between plasma MCH concentrations of black- and white-reared fish and the cortisol concentration. MCH had no direct effect on the secretion of cortisol by interrenal tissue but incubated hypothalami, in which endogenous MCH had been immunoabsorbed, provided evidence that MCH can depress the release of corticotrophin-releasing bioactivity.
Journal of Endocrinology (1991) 128, 267–274
The role of endothelin in the control of adrenocortical function: stimulation of endothelin release by ACTH and the effects of endothelin-1 and endothelin-3 on steroidogenesis in rat and human adrenocortical cells
Authors: Hinson J. P. , Vinson G. P. , Kapas S. , Teja R. 
Published: December 2008

ABSTRACT
The rate of blood flow through the intact adrenal gland is closely linked to steroid hormone secretion, and although the mechanism involved is unknown, it is thought to involve secretory products of the vascular endothelium.
In dispersed cell preparations, endothelin-1 and -3 both caused a dose-dependent and highly sensitive increase in steroid secretion by zona glomerulosa and zona fasciculata cells of the rat and human adrenal cortex. In addition, when the perfused rat adrenal was stimulated with ACTH, significant increases in steroid secretion and perfusion medium flow rate were accompanied by significantly increased secretion of immunoreactive endothelin into the adrenal vein. It is proposed that endothelin has a role in mediating the adrenocortical response to ACTH stimulation.
Journal of Endocrinology (1991) 128, 275–280
Effects of an antiserum to rat growth hormone and bromocriptine on cholesterol-metabolizing enzymes in the lactating rat mammary gland
Authors: Shand J. H. , West D. W. 
Published: December 2008

ABSTRACT
Rats in mid-lactation were treated, for 2 days, with anti-rat GH serum (anti-rGH) and/or bromocriptine before microsomes were prepared from the freeze-clamped mammary glands. The effects of these anti-hormone treatments on the concentrations of microsomal cholesterol and cholesterol esters and on the activities of acyl-CoA:cholesterol acyltransferase (ACAT), neutral cholesterol ester hydrolase and 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) were measured. HMG-CoA reductase was determined in microsomes prepared in both the presence and absence of phosphatase inhibitors to determine the expressed and total activities respectively.
Anti-rGH reduced HMG-CoA reductase and increased microsomal cholesterol and cholesterol esters. Bromocriptine reduced HMG-CoA reductase but increased all of the other parameters. The results indicate that the initial stage in the stimulation of milk secretion involves a decrease in the activity of ACAT and that the phosphorylation level of HMG-CoA reductase is modulated by both prolactin and GH acting in opposition.
Journal of Endocrinology (1991) 128, 287–295
Radioimmunoassay for insulin-like growth factor-I: solutions to some potential problems and pitfalls
Authors: Breier B. H. , Gallaher B. W. , Gluckman P. D. 
Published: December 2008

ABSTRACT
This report describes essential requirements for the validation of a radioimmunoassay (RIA) for insulin-like growth factor-I (IGF-I) and presents solutions to some problems and pitfalls commonly observed. The preparation of IGF-I to be used as radioligand or standard has to be selected carefully since some IGF-I preparations are contaminated with variants which demonstrate different potencies for different antisera used in the RIA.
Accurate assessment of IGF-I levels in blood plasma requires an efficient extraction method for the IGF-binding proteins (IGFBPs). Extraction methods to remove the influence of IGFBPs in the RIA were compared using blood plasma of considerable differences in IGF-I/IGFBP ratios. Acidification of plasma before column chromatography on Sephadex G-75 (G75) is generally considered to be the most reliable extraction method, but it is very time-consuming. The acid–ethanol extraction (AE) of plasma is not valid in many situations. Non-parallel displacement to the IGF-I standard was observed with AE-extracted plasma samples in the RIA. In addition, a comparison of IGF-I values obtained in the RIA after AE or G75 extraction of fetal ovine plasma has shown no significant correlation.
We report an extraction technique based on a modified AE extraction followed by cryo-precipitation (AEC). AEC extraction on blood plasma reduced residual IGFBPs to a level that did not interfere in the assay. Furthermore, AEC-extracted plasma samples showed parallel displacement in the RIA to highly purified preparations of authentic IGF-I. We observed high correlations, with a slope close to unity, of IGF-I values obtained in the RIA using the AEC or G75 extraction for plasma from different species including adult and fetal sheep, rat, mouse and man. The AEC extraction provides a rapid and simple alternative to G75 extraction for blood plasma from a variety of species provided that high-affinity antisera are used for the RIA.
Journal of Endocrinology (1991) 128, 347–357
Differential effects of epidermal growth factor on the differentiation of type A spermatogonia in adult mouse cryptorchid testes in vitro
Authors: Haneji T. , Koide S. S. , Tajima Y. , Nishimune Y. 
Published: December 2008

ABSTRACT
The effect of epidermal growth factor (EGF) on testicular germ cell differentiation was investigated. Testicular fragments from surgically prepared cryptorchid testes of adult mice were cultured for 9 days in serum-free media containing various concentrations of EGF. Histological sections of testis were examined under a light microscope and each type of germ cell and mitotic cell in the seminiferous tubules was counted per 1000 Sertoli cells. EGF at concentrations ranging from 100 to 200 ng/ml induced differentiation of type A spermatogonia. The observed maximal stimulatory activity of EGF at a concentration of 100 ng/ml was 30% of the positive control cultures treated with calf serum. EGF at concentrations ranging from 1 to 100 ng/ml significantly inhibited the mitotic activity of FSH, FSH plus retinol, or FSH plus fetuin on type A spermatogonia and their differentiation. The number of type A spermatogonia in testes cultured with FSH, FSH plus retinol, or FSH plus fetuin decreased when EGF was added. On the other hand, EGF stimulated the differentiation of type A spermatogonia induced with fetuin but did not influence retinol-induced differentiation. It is proposed that EGF inhibits testicular germ cell differentiation by blocking the proliferation of type A spermatogonia stimulated by FSH.
Journal of Endocrinology (1991) 128, 383–388
Effects of bovine follicular fluid on the secretion of LH and FSH in inhibin-immunized seasonally anoestrous ewes
Authors: Knight P. G. , Wrathall J. H. M. , Glencross R. G. , McLeod B. J. 
Published: December 2008

ABSTRACT
It has been shown previously that treatment of seasonally anoestrous ewes with steroid-free bovine follicular fluid (FF), a crude inhibin-containing preparation, leads to a decrease in plasma FSH level which is accompanied by a marked increase in pulsatile LH secretion. Since FF contains several factors (e.g. activin, follistatin, unidentified components) other than inhibin, which might act to modify gonadotrophin secretion, it was of interest to establish whether these concurrent effects of FF on FSH and LH secretion persisted in ewes which had been actively immunized against a synthetic peptide replica of the α subunit of bovine inhibin. In June 1989 (anoestrous period) groups of inhibin-immune and control ewes (n = 5 per group) received 6-hourly s.c. injections of either bovine serum (2 ml) or one of two doses of FF (0·5 ml or 2 ml) for 3 days. Blood was withdrawn at 6-h intervals for 6 days beginning 24 h before the first injection. On the final day of treatment, additional blood samples were withdrawn at 15-min intervals for 8 h to monitor pulsatile LH secretion. Ewes were then challenged with exogenous gonadotrophin-releasing hormone (GnRH; 2 μg i.v. bolus) to assess pituitary responsiveness. In control ewes, FF promoted a dose-dependent suppression of basal (maximum suppression 65%; P < 0·01) and post-GnRH (maximum suppression 72%; P < 0·01) levels of FSH in plasma. This was accompanied by an increase (P < 0·01) in LH pulse frequency from 1·40±0·24 (s.e.m.) to 3·20±0·37 pulses/8 h. In contrast, FF did not affect secretion of either FSH or LH in inhibin-immunized ewes. However, mean plasma LH levels in immunized ewes were significantly lower (43%; P < 0·02) than in control ewes, irrespective of treatment. These findings indicate that in the anoestrous ewe the ability of FF to suppress plasma FSH is due entirely to its content of inhibin, that FF-induced enhancement of pulsatile LH secretion is mediated by inhibin, rather than some additional component of FF, and that immunoneutralization of endogenous inhibin can reduce LH secretion.
Journal of Endocrinology (1991) 128, 403–410
The effect of genetic selection for milk yield on the response to growth hormone secretagogues in immature cattle
Authors: Løvendahl P. , Angus K. D. , Woolliams J. A. 
Published: December 2008

ABSTRACT
Eighty 4-month-old calves of both sexes and of two selected lines differing by 70 kg in their predicted total yield of milk fat and protein were injected intravenously with three of four GH secretagogues: these were, per kg liveweight; (i) 0·2 μg human GH-releasing factor(1–29) (GRF), (ii) 0·2 μg TRH, (iii) a combination of (i) and (ii), and (iv) 0·1 g arginine hydrochloride. The response of GH was measured for 2 h following administration. Geometric mean concentration of the 5-, 10-, 15- and 20-min samples following GRF, TRH and their combination were 29·3, 19·5 and 156 μg/l compared with baseline means of 6·5, 10·0 and 12·6 μg/l respectively, and for arginine (in which the mean response included the 30-min instead of the 5-min sample) 14·6 μg/l compared with a baseline of 8·31 μg/l. The line selected for greater yield responded more to each secretagogue by 1·53-fold following GRF (P < 0·01), 1·34-fold following TRH (P < 0·05), 1·11-fold following the combination (P > 0·01) and 1·26-fold following arginine (P < 0·1). Females responded 2·3-fold more than males following GRF administration (P < 0·001), only 1·2-fold more following TRH (P > 0·1), but less (0·63-fold) than males when GRF was combined with TRH (P < 0·05). For all secretagogues the concentration of GH before administration was important in determining the size of response (P < 0·001). It was concluded that the increased release of GH following the administration of GRF and TRH was a direct result of selection for dairy merit and that increased yields during lactation may, in part, be mediated directly through pituitary responsiveness.
Journal of Endocrinology (1991) 128, 419–424
Cholecalciferol has no effect on calcium and inorganic phosphorus balance in a naturally cholecalciferol-deplete subterranean mammal, the naked mole rat (Heterocephalus glaber)
Authors: Buffenstein R. , Yahav S. 
Published: December 2008

ABSTRACT
Naked mole rats, Heterocephalus glaber, have no obvious source of cholecalciferol (D3) available to them, given their underground habitat and tubiferous diet. They have undetectable levels of 25-OH-D3 and as such appear to be naturally deplete in D3. The effect of an oral D3 supplement on mineral balance and homeostasis was therefore investigated.
This D3 treatment did not affect circulating levels of Ca2+ and inorganic phosphorus (Pi). Nor did D3 treatment affect mineral intake and absorption. The Ca2+ and Pi present in the food was efficiently extracted and absorbed, resulting in an apparent fractional absorption (AFA) efficiency exceeding 98%. Irrespective of D3 treatment, the amount of Ca2+ and Pi absorbed was positively correlated with the amount ingested, suggesting that intestinal uptake is by a passive D3-independent process. After D3 supplementation urinary Ca2+ secretion was unchanged; however, the amount of Pi excreted in the urine increased (P ≤ 0·05). This resulted in a concomitant decline in Pi AFR (P ≤ 0·02 from 99·95±0·02% to 99·82±0·03%). Almost all the Ca2+ and Pi in the glomerular filtrate were reabsorbed, facilitating AFR efficiencies that approach physiological maxima (> 99%). Changes in AFR efficiency with D3 supplementation are therefore of no biological significance. Net mineral flux of both elements, irrespective of D3 treatment, was positive. It is speculated that the ever-growing incisors of these animals act as mineral dumps and assist in the tight regulation of plasma Ca2+ and Pi.
These data suggest that naked mole rats utilize mechanisms independent of D3 in regulating mineral homeostasis and are therefore well-adapted to an environment devoid of sunlight.
Journal of Endocrinology (1991) 129, 21–26
Effects of truncated glucagon-like peptide-1 on the responses of starved sheep to glucose
Authors: Faulkner A. , Pollock H. T. 
Published: December 2008

ABSTRACT
The effects of i.v. glucagon-like peptide-1-(7–36)amide (GLP-1; 10 μg) on starved sheep given an i.v. glucose load (5 g) were studied. Plasma insulin concentrations rose significantly more after glucose administration in fed than in starved sheep. Giving GLP-1 to starved sheep increased the insulin response to the glucose load. The rise in plasma insulin concentrations in starved sheep given GLP-1 was similar to that observed in fed sheep. Plasma glucose concentrations returned to normal values more quickly in the starved sheep given GLP-1 than in starved sheep not given gut hormone. Plasma concentrations of free fatty acid, urea and α-amino nitrogen decreased more quickly following glucose administration in starved sheep given GLP-1 than in those not given GLP-1. The data suggest a role for GLP-1 in regulating plasma insulin concentrations and hence metabolism in ruminant animals. The possible role of gut hormones in ruminants is discussed.
Journal of Endocrinology (1991) 129, 55–58
Immunohistochemical and in-situ hybridization analysis of androgen receptor expression during the development of the mouse prostate gland
Authors: Takeda H. , Chang C. 
Published: December 2008

ABSTRACT
Ontogeny of the androgen receptor in the mouse prostate during fetal and post-natal periods was re-evaluated by histochemistry using a monoclonal antibody and by in-situ hybridization using a cDNA probe. Unlike steroid autoradiographic techniques which show ligand-binding sites in autoradiographs, these two techniques make it possible to investigate the expression of receptor protein and the transcription of its mRNA directly at the cellular level. Our previous autoradiographic data have demonstrated that only the mesenchyme takes up androgen during the fetal period; no incorporation of androgen by the epithelium has been observed in the fetus, although this does occur in later development. This observation indicated that the morphogenesis of prostatic epithelium is induced by the androgen-activated surrounding mesenchyme. In the post-natal prostate, the present data are nearly the same as those obtained by autoradiographic techniques; ligand-binding activity and expression of the receptor and its mRNA are much higher in the epithelium than in the stroma. On the other hand, the present study indicated that the fetal epithelium, which had shown no ligand-binding activity by autoradiographic analysis, expressed the same amount of receptor protein and its mRNA as the fetal mesenchyme. The results suggest that androgen receptor protein is expressed in the fetal epithelium but may not be able to bind to androgens until post-natal development.
Journal of Endocrinology (1991) 129, 83–89
Effects of corticosterone on the secretion of corticotrophin-releasing factor, arginine vasopressin and oxytocin into hypophysial portal blood in long-term hypophysectomized rats
Authors: Sheward W. J. , Fink G. 
Published: December 2008

ABSTRACT
To investigate the feedback effects of corticosterone on the secretion of corticotrophin-releasing factor-41 (CRF-41), oxytocin and arginine vasopressin (AVP), hypophysial portal vessel blood was collected from control (intact) and long-term (6–8 weeks) hypophysectomized rats. In preliminary experiments in rats anaesthetized with urethane, long-term hypophysectomy resulted in a significant increase in the secretion of oxytocin and AVP; the hypothalamic contents of oxytocin and AVP were also increased in comparison with pituitary-intact rats. In long-term hypophysectomized rats anaesthetized with sodium pentobarbitone, but not with urethane, the output of CRF-41 into portal blood was increased twofold in comparison with that in control rats. In long-term hypophysectomized rats anaesthetized with pentobarbitone, the i.v. infusion of corticosterone (7·2 nmol/min) for a 2 h period of portal blood collection did not alter the secretion of CRF-41, oxytocin or AVP into portal blood; however, the secretion of CRF-41 and, to a lesser extent, AVP was significantly reduced in hypophysectomized rats by continuous corticosterone replacement, by a pellet of corticosterone implanted s.c. for 5 days before portal blood collection. These results confirm that the secretion of CRF-41 is differently affected by the anaesthetics urethane and pentobarbitone, and in long-term hypophysectomized rats show (i) that there were no apparent feedback effects of corticosterone infusion over a 2 h period on the secretion of any of the peptides studied, (ii) that late delayed feedback effects of continuous administration of corticosterone are mediated by a reduction in CRF-41 and AVP output, and (iii) that corticosterone has no effects on oxytocin secretion into portal blood.
Journal of Endocrinology (1991) 129, 91–98
Regional differences in catecholamine concentrations in bovine ovaries analysed by high-performance liquid chromatography
Authors: Denning-Kendall P. A. , Wild M. L. , D. C. Wathes 
Published: December 2008

ABSTRACT
Bovine corpora lutea and ovarian stroma were analysed by high-performance liquid chromatography for catecholamine content. High concentrations (up to 102 nmol/g wet weight) were found in both 'central' stroma, containing many blood vessels, and 'peripheral' stroma. Central stroma contained noradrenaline and some dopamine, whereas peripheral stroma contained a higher proportion of dopamine and also significant amounts of 3,4-dihydroxyphenylacetic acid (DOPAC). Occasional samples of stroma had very high amounts of dopamine, suggesting that it is stored in specific regions. Corpora lutea, although devoid of direct innervation, contained dopamine (up to 5·3 nmol/g) and noradrenaline (up to 1·2 nmol/g). The average dopamine: noradrenaline molar ratio was 1·19 : 1 and the concentrations of dopamine and noradrenaline were highly correlated (P < 0·002). The concentration of dopamine was significantly higher in the early luteal phase of the oestrous cycle than during the rest of the cycle or in pregnancy. The levels of noradrenaline and dopamine present in corpora lutea are sufficient to modulate the production of both oxytocin and progesterone by luteal cells in vitro.
Journal of Endocrinology (1991) 129, 221–226
Androgen receptor in the Harderian gland of Rana esculenta
Authors: d'Istria M. , Chieffi-Baccari G. , Di Matteo L. , Minucci S. , Varriale B. , Chieffi G. 
Published: December 2008

ABSTRACT
An androgen receptor has been identified in the cytosolic and nuclear extracts of the Harderian gland of the frog, Rana esculenta. A single class of high-affinity binding sites was found: Kd = 1·9±1·3 (s.d.) nmol/l (n = 26) for the cytosolic extract and Kd = 0·9±0·8 nmol/l (n = 15) for the nuclear extract. The presence of binding activity in both nuclear and cytosolic extracts and the low rate of ligand-receptor dissociation are characteristics that distinguish this receptor from a steroid-binding protein. The Kd did not show any sex difference and did not exhibit any secretory activity-related change. Binding in both cytosolic and nuclear extracts was specific for androgens (testosterone = 5α-dihydrotestosterone); oestradiol-17β showed a 30% cross-reaction; moreover, specific binding of [3H]oestradiol-17β was not detectable. The binding capacity of the Harderian gland increased progressively in both fractions from October to December, reaching a peak in May, and decreased suddenly during July to August.
The lack of any morphological sex-related difference in the Harderian gland of the green frog might be accounted for by the high amount of circulating androgens as well as a similar concentration of androgen receptor in both sexes.
Journal of Endocrinology (1991) 129, 227–232
Thyrotrophin, but not forskolin, increases intracellular free calcium and calmodulin in pig thyroid cells
Authors: Ye Q. L. , Wagner M. , Smythe S. , Neil S. Mac 
Published: December 2008

ABSTRACT
The effects of TSH and forskolin were examined on intracellular free calcium ([Ca2+]i) and calmodulin in normal pig thyroid cells in culture. TSH was found to produce acute increases in [Ca2+]i in pig cells. Responses were seen at concentrations of TSH between 0·01 and 10 mU/ml. Sensitivity to TSH was greater in adherent monolayers of cells than in cell suspensions and was also greater in subconfluent rather than confluent monolayers of cells. The increase in [Ca2+]i in response to TSH represented just over a doubling in [Ca2+]i whether examined at 22 °C or 37 °C. Forskolin failed to affect [Ca2+]i. TSH increased [Ca2+]i in the absence of extracellular calcium.
TSH, but not forskolin, produced a significant increase in intracellular calmodulin after 3 days of culture of cells with TSH. The increase in calmodulin was of the order of 60% and did not relate to any effect of TSH on thyroid cell number.
Journal of Endocrinology (1991) 129, 291–299