bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seminiferous tubule androgen receptors in experimental cryptorchidism
Authors: Winters S. J. 
Published: December 2008

ABSTRACT
As an initial approach to the study of seminiferous tubule androgen receptors in disordered spermatogenesis, cytosol androgen receptors were studied in rats with experimental cryptorchidism. Two weeks after the testis had been repositioned in the abdomen of 6-week-old rats, the animals were hypophysectomized to deplete the testis of androgen, and 1 week later they were killed. Androgen receptor binding was studied in seminiferous tubule cytosol using [3H]methyltrienolone as the radiolabelled probe. The androgen-binding capacity of cryptorchid testis, when expressed as fmol bound/testis, was reduced to 50% of control, in parallel with the decline in testis weight. No change in binding affinity was found. Sucrose density gradient centrifugation using a vertical tube rotor revealed a 9S molybdate-stabilized receptor under low-salt conditions in both cryptorchid and scrotal seminiferous tubule cytosol. Receptor-complex stability studies, analysis by gel filtration and DEAEcellulose chromatography produced similar results in cryptorchid and scrotal tubules. The mechanism for the reduction in testicular receptor content of an abdominal testis remains to be clarified. The demonstration that testicular androgen receptors can be reduced by cryptorchidism suggests that further studies may indicate the role of receptor binding in testicular function.
J. Endocr. (1986) 109, 427–433
EVIDENCE FOR GRANULOSA-THECA INTERACTION IN THE SECRETION OF OXYTOCIN BY BOVINE OVARIAN TISSUE
Authors: Jungclas B. , Luck M.R. 
Published: December 2008

ABSTRACT
We have examined the ability of granulosa cells, from carefully selected preovulatory bovine follicles, to secrete oxytocin in vitro. Although cells from 83% of follicles underwent functional luteinisation (greatly increased progesterone secretion) in serum-supplemented culture, only 69% had cells capable of oxytocin secretion. Secretion followed a similar time course in all cultures, with the peak appearing on day 3. Oxytocin, but not progesterone, output could be consistently increased by addition of pieces of theca interna tissue, or theca conditioned medium, to the cultures. The effect could be achieved by exposure to theca tissue at any time prior to peak output without altering the time course of secretion. Oxytocin could not be detected in follicular fluid from any of the selected follicles, nor in medium from theca cultured alone. We conclude that the potential for oxytocin secretion is a feature of follicular maturation which is lost during atresia and that the stimulus to secretion is associated with luteinisation but not with progesterone output. Finally, the intermixing of follicular cells during corpus luteum formation may provide a mechanism for the enhancement of oxytocin secretion within a predetermined time frame.
Effects of hypophysectomy and growth hormone infusion on rat hepatic carbonic anhydrases
Authors: Jeffery S. , Wilson C. A. , Mode A. , Gustafsson J.-Å. , Carter N. D. 
Published: December 2008

ABSTRACT
Rat liver exhibits a reversed sexual dimorphism of its two endogenous soluble carbonic anhydrase (CA) isozymes, CA II and CA III. Normal males have hepatic CA III concentrations ten–twenty times those in the female, while female liver contains two–three times more CA II than the male. Hypophysectomy abolishes this sexual differentiation, having no effect on male liver but producing isozyme concentrations in the female liver similar to those in the male. Infusion of a continuous level of GH into male rats induces a female-like isozyme pattern for both CA II and CA III.
J. Endocr. (1986) 110, 123–126
Field evaluation of a pregnancy immunoassay for the detection of oestrone sulphate in goats
Authors: McArthur C. P. , Geary A. 
Published: December 2008

ABSTRACT
The concentration of oestrone sulphate in whey obtained from 66 pregnant dairy goats was measured by direct radioimmunoassay. The mean time at which pregnancy was first detected was day 41 of gestation. Levels remained low (37 pmol/l–0·96 nmol/l, mean = 167 pmol/l) until week 5 of gestation when they rose rapidly. The test had an accuracy of 95·6%, was able to distinguish true from pseudopregnancy, and suggested that pregnancy in females carrying multiple fetuses could be detected earlier, possibly as a result of the fetal-placental origin of oestrone sulphate.
J. Endocr. (1986) 110, 133–136
Radioimmunoassay of pineal 5-methoxytryptophol in different species: comparison with pineal melatonin content
Authors: Skene D. J. , Smith I. , Arendt J. 
Published: December 2008

ABSTRACT
A sensitive, specific, reproducible and practical radioimmunoassay for the determination of 5-methoxytryptophol (ML) in pineal glands of different species has been developed. High-affinity specific antisera were produced by immunization of sheep with ML–bovine serum albumin. Iodinated ML, used as the radiolabel, was synthesized by direct iodination of ML using 1,3,4,6,-tetrachloro-3,6-diphenylglycouril as the oxidant. Sensitivity of the assay was 0·005 pmol/tube. The validity of the assay was checked using classical techniques. Cross-reactivity with other indoles was negligible. Parallel inhibition curves were obtained for rat, hamster, sheep and tortoise pineal homogenates. Using thin-layer chromatography, tortoise pineal immunoreactivity also co-chromatographed with standard ML. Samples (n = 5) with ML concentrations of 0·013, 0·052 and 0·209 pmol/tube had intra-assay coefficients of variation of 9·8, 5·7 and 7·6% respectively. Their respective interassay coefficients of variation were 17·7 16·5 and 11·4% (n = 8). The pineal concentration of ML was found to be species dependent. Afternoon ML levels were 0·052± 0·002 (s.e.m.) pmol/gland in the rat (n = 16), 0·539 ±0·089 pmol/gland in the hamster (n = 16), 1·73±0·225 nmol/g in the sheep (n = 10) and 7·15± 0·465 pmol/gland in the tortoise (n = 4). The ratio of ML:melatonin content in the pineal gland also showed a large interspecies variation with values of 0·02 in the rat, 0·22 in the sheep, 2·7 in the hamster and 17 in the tortoise.
J. Endocr. (1986) 110, 177–184
Gestational changes in the level of glucocorticoid-binding sites in fetal bovine cartilaginous tissues
Authors: Kan K. W. , Cruess R. L. 
Published: December 2008

ABSTRACT
In order to assess glucocorticoid actions on fetal cartilage development, [3H]dexamethasone binding site levels in fetal bovine cartilaginous tissues from long bones were measured, using a whole cell assay at 37 °C. Displaceable [3H]dexamethasone binding in epiphysial growth cartilage was maximal (16·2 fmol/106 cells) in fetuses of 10–15 cm crown–rump length (CR), and declined to 22% of the maximum in fetuses of 20–30 cm CR. Subsequently, [3H]dexamethasone binding rose to a plateau (13·0 fmol/106 cells) in fetuses of 30–80 cm CR and declined in those of 80–100 cm CR. When measured in growth plate cartilage, [3H]dexamethasone binding was significantly higher in fetuses of 40–80 cm CR (39 fmol/106 cells) than in those of 80–100 cm CR. There was no significant change of [3H]dexamethasone binding affinities in epiphysial chondrocytes of 5–100 cm CR fetuses or in growth plate chondrocytes of 40–100 cm CR fetuses.
These results demonstrate that fetal cartilaginous tissues during development possess varying cellular levels of glucocorticoid binding and may thus have temporal changes in sensitivity to glucocorticoid hormones.
J. Endocr. (1986) 110, 257–262
Initiation of ovarian follicular maturation without a surge of FSH in cyclic rats treated with antiserum to LH-releasing hormone
Authors: Matsuzono N. , Taya K. , Watanabe G. , Sasamoto S. 
Published: December 2008

ABSTRACT
The relationship between a surge of FSH and the initiation of follicular maturation was examined using rats with a 4-day oestrous cycle. When antiserum against LH-releasing hormone (LHRH-AS) was given at 13.00 h on the day of pro-oestrus (day 0), surges of FSH and LH were blocked. Plasma FSH and LH were maintained at low basal levels without a surge release until the next spontaneous surge occurred on the afternoon of day 4, the predicted day of pro-oestrus. Follicular responsiveness to an injection of human chorionic gonadotrophin (hCG) indicated that preovulatory follicles, present at the time of treatment with LHRH-AS, were capable of ovulating on day 1 but had regressed by day 2. Subsequently, as shown by the ovulatory response to hCG, a new set of follicles had begun to mature by the morning of day 3 without a preceding surge of FSH. Changes in oestradiol-17β levels in the plasma throughout the oestrous cycle were the same in rats injected with LHRH-AS or non-immune control serum. The mature follicles in the rats treated with LHRH-AS thus retained the capacity to ovulate after losing their ability to secrete oestrogen.
These results suggest that an FSH surge is not essential for initiation of follicular maturation and that basal levels of FSH may be enough to initiate follicular maturation in the absence of newly formed corpora lutea.
J. Endocr. (1986) 110, 279–285
Effect of hydrogen ion concentration on aldosterone secretion by isolated perfused canine adrenal glands
Authors: Radke K. J. , Taylor R. E. , Schneider E. G. 
Published: December 2008

ABSTRACT
The direct effects of changes in extracellular hydrogen ion (H+) concentration on aldosterone secretion under basal, angiotensin II- and potassium-stimulated conditions were studied in isolated, perfused canine adrenal glands. Changes in extracellular H+ concentration were induced by altering either the partial pressure of CO2 (pCO2) or the HCO3− concentration of the perfusate. Acid-base disturbances had a more pronounced effect on aldosterone secretion under stimulated than under basal conditions. Increasing H+ concentration enhanced angiotensin II- and potassium-stimulated aldosterone secretion, whereas decreasing H+ concentration markedly inhibited the secretory response to these stimuli. Because changes in H+ concentration, whether produced by varying extracellular pCO2 or extracellular HCO3− concentration, had similar effects on angiotensin II-stimulated aldosterone secretion, the data suggest that H+ concentration per se is the important determinant of the aldosterone secretory rate. Interestingly, during the immediate recovery period from pCO2-induced alkalosis under both angiotensin II- and potassium-stimulated conditions, aldosterone secretion always returned to a value significantly higher than that obtained just before alkalosis. The results of this study demonstrate that changes in extracellular H+ concentration influence the rate of aldosterone secretion, possibly via changes in intracellular pH, by a direct action on the canine adrenal gland. Therefore, when evaluating the control of aldosterone secretion, the acid-base status of the whole animal or of in-vitro adrenal tissue must be considered.
J. Endocr. (1986) 110, 293–301
Establishment of a continuous somatostatin-producing line of medullary thyroid carcinoma cells from BALB/c mice
Authors: Tischler A. S. , Lee Y. C. , Costopoulos D. , Nunnemacher G. , DeLellis R. A. , Van Zwieten M. J. , Wolfe H. J. , Bloom S. R. 
Published: December 2008

ABSTRACT
A continuous line of somatostatin-producing medullary thyroid carcinoma cells was established from a transplantable tumour in BALB/c mice. Virtually all of the somatostatin immunoreactivity co-chromatographed with somatostatin 14. The tumour cells replicated in spinner cultures with a doubling time of approximately 4 days, and the concentration of somatostatin released into the culture medium increased in proportion to the number of cells. Two-to threefold increases in amounts of stored and released somatostatin were observed after treatment of the cells with bromodeoxyuridine. This cell line might be valuable for studies of somatostatin regulation in normal and neoplastic C-cells, and for other studies of C-cell biology which require a mouse model.
J. Endocr. (1986) 110, 309–313
Unique calcium dependencies of the activating mechanism of the early and late aldosterone biosynthetic pathways in the rat
Authors: Schiebinger R. J. , Braley L. M. , Menachery A. , Williams G. H. 
Published: December 2008

ABSTRACT
This study compared the extracellular calcium dependency and the enzymatic locus of that dependency for N6,O2′-dibutyryl cyclic AMP (dbcAMP)-, angiotensin II- and potassium-stimulated aldosterone secretion in dispersed rat glomerulosa cells. The need for extracellular calcium, calcium influx, and specifically for calcium influx through the calcium channel was examined. dbcAMP, angiotensin II and potassium, in the presence of calcium (3·5 mmol/l), significantly (P < 0·01) increased aldosterone output by at least 1·5-fold. Yet in the absence of extracellular calcium or in the presence of lanthanum (an inhibitor of calcium influx by most mechanisms) all three stimuli failed to increase aldosterone secretion. Nifedipine, a dihydropyridine calcium channel antagonist, significantly (P < 0·01) reduced angiotensin II- and potassium-stimulated aldosterone secretion, but had no effect on dbcAMP-stimulated aldosterone secretion (100 ± 14 vs 105 ± 19 pmol/106 cells). Likewise nitrendipine failed to inhibit ACTH-stimulated aldosterone secretion.
Angiotension II and potassium activation of both the early aldosterone biosynthetic pathway (as reflected by pregnenolone production in the presence of cyanoketone) and also its late pathway (as reflected by the conversion of exogenous corticosterone to aldosterone in the presence of cyanoketone) were significantly (P < 0·01) inhibited by lanthanum, nifedipine and by reducing the extracellular calcium concentration. However, with dbcAMP stimulation, none of these manipulations modified pregnenolone production. Late pathway activation by dbcAMP was inhibited by lanthanum and a reduction in extracellular calcium, but not by nifedipine.
These observations suggest that: (1) the extracellular calcium dependency of dbcAMP-, angiotensin II- and potassium-stimulated aldosterone secretion reflects a need for calcium influx; (2) with dbcAMP stimulation, activation of the late pathway is dependent on calcium influx by a calcium channel-independent mechanism, whereas activation of the early pathway is not dependent on extracellular calcium or calcium influx and (3) activation of both the early and late pathway by angiotensin II and potassium is dependent on calcium influx by a calcium channel-dependent mechanism. Therefore, we conclude that the mechanism of activation of the early aldosterone biosynthetic pathway by dbcAMP is different from angiotensin II or potassium and early pathway activation is distinct from that of late pathway activation with dbcAMP stimulation.
J. Endocr. (1986) 110, 315–325
Vasopressin, but not oxytocin, is released in response to water deprivation in conscious goats
Authors: Thornton S. N. , Leng G. , Bicknell R. J. , Chapman C. , Purdew T. 
Published: December 2008

ABSTRACT
Plasma samples obtained at 4-h intervals from goats for at least 24 h before and then during 24 h of deprivation of water were analysed by radioimmunoassay for vasopressin and oxytocin concentrations. The samples were also analysed for osmolality and sodium concentration. The differential effect of night/day versus day/night deprivation was also studied. During the two periods before the two deprivations osmolality varied in a regular manner, with low values occurring at 08.00 h. Sodium concentration followed osmolality, whereas vasopressin did not vary during the period before deprivation. During deprivation vasopressin increased along with osmolality and sodium concentration, with the beginning of the increase occurring after the morning feed. Oxytocin levels did not increase during the period of deprivation.
These results do not support the hypothesis of general release of neurohypophysial hormones in response to osmotic stimuli but instead indicate there are species variations with respect to hormonal response to water deprivation.
J. Endocr. (1986) 110, 335–340
Measurement of exogenous and endogenous inhibin in sheep serum using a new and extremely sensitive bioassay for inhibin based on inhibition of ovine pituitary FSH secretion in vitro
Authors: Tsonis C. G. , McNeilly A. S. , Baird D. T. 
Published: December 2008

ABSTRACT
An extremely sensitive and reliable bioassay for inhibin based on inhibition of ovine pituitary FSH secretion in vitro was developed and used to measure exogenous and endogenous inhibin activity in the ewe. The sheep inhibin bioassay is 30- to 40-fold more sensitive than conventional rat inhibin bioassays. The minimum sensitivity of each bioassay in the measurement of inhibin activity in 1 ml of sheep serum is 220 mu. and 4080 mu. in the sheep and rat bioassays respectively. This sensitive inhibin bioassay has permitted, for the first time, the measurement of endogenous inhibin in the peripheral and ovarian vein blood of the sheep, as well as exogenously administered inhibin.
The half-life of exogenously administered ovine inhibin (in follicular fluid) in the sheep was calculated as two components (18–24 and 50–60 min) from the inhibin profiles of six ewes. Inhibin contained in the ovine follicular fluid, given as a bolus i.v. injection, increased to maximum levels after 5 min and then remained increased for 10–32 min depending upon the dose administered, before exponentially decaying. The time for inhibin to exert its effect ranged from 3 to 6 h after injection and appeared to be dose-related. The bolus injection of inhibin, apart from causing suppression of FSH, evoked a large rebound increase of FSH up to 400% of preinjection levels.
The development of the sheep bioassay will allow the measurement of biologically active inhibin in the peripheral circulation and ovarian vein blood of sheep with the possibility of extending this to man.
J. Endocr. (1986) 110, 341–352
Effects of long- and short-term gonadectomy on the hypothalamo-hypophysial (LH-releasing hormone–LH) system in oestrogen-treated male and female rats
Authors: Weiland N. G. , Barraclough C. A. , Catt K. J. 
Published: December 2008

ABSTRACT
Considerable differences have previously been found in the hypothalamo-hypophysial responsiveness to oestrogen, depending upon the time between gonad removal and exposure to oestrogen. In the present study a detailed analysis was made of some of the differences which may exist in pituitary LH-releasing hormone (LHRH) receptors and the amount of LH released in response to electrochemical depolarization of the medial preoptic area after 2 or 7 days of oestradiol treatment of long- and short-term gonadectomized male and female rats. The pituitary glands of long-term gonadectomized males and females secreted more LH in response to two pulse injections of LHRH than did short-term gonadectomized rats. The amount of LH released on day 2, however, was equivalent to that secreted after 7 days of oestradiol treatment. Moreover, long-term gonadectomized males and females had equivalent LHRH receptor concentrations, which were greater than those of short-term gonadectomized animals. Peak serum LH concentrations observed after preoptic stimulation were equivalent in short- and long-term castrated rats after 2 days of oestrogen exposure. Serum LH concentrations following preoptic stimulation in short-term gonadectomized males and females were significantly greater on day 7 than on day 2 of oestradiol treatment, whereas in long-term gonadectomized animals the stimulated release of LH was equivalent both in magnitude and time of peak release on both days.
These studies demonstrate that the differential effects of oestradiol on LH release on day 2 (no negative feedback) compared with day 7 (both negative and positive feedback exist) are not due to differences in the ability of the pituitary gland to release LH in response to LHRH, nor in the releasable pools of hypothalamic LHRH in long-term gonadectomized rats. Rather, they seem to be due to a refractoriness in some unidentified central nervous process which regulates tonic LH release in gonadectomized rats.
J. Endocr. (1986) 110, 367–373
In-vivo studies of a human-thyrotrophin preparation
Authors: Law A. , Jack G. W. , Tellez M. , Edmonds C. J. 
Published: December 2008

ABSTRACT
The effects on thyroid function of a new preparation of human thyrotrophin (hTSH) were studied in four subjects whose endogenous production of TSH had been suppressed by administration of thyroxine (T4). The hTSH, prepared from human cadaveric pituitary glands and highly purified using a monoclonal antibody technique, was given as an intravenous bolus of 2 i.u. hTSH. Serum TSH levels rose rapidly to a maximum of about 150 mu./l and then declined exponentially with a half-life of 100 min. After injection, the hTSH distributed rapidly in a volume averaging about 13 litres which corresponded approximately to the expected extracellular fluid volume of the subjects. Serum free tri-iodothyronine and free T4 rose significantly, reaching a maximum between 4 and 8 h after injection of hTSH; serum thyroglobulin was not altered significantly. The rise of thyroid pertechnetate uptake, a measure of the thyroid iodide uptake, occurred later, being only slightly increased at 8 h after administration of hTSH and reaching a maximum at 24 h.
J. Endocr. (1986) 110, 375–378
Dopamine does not attenuate phosphoinositide hydrolysis in rat anterior pituitary cells
Authors: Canonico P. L. , Jarvis W. D. , Judd A. M. , MacLeod R. M. 
Published: December 2008

ABSTRACT
The hydrolysis of membrane phosphatidylinositol to yield [3H]labelled inositol phosphates by anterior pituitary cells was stimulated significantly by angiotensin II, TRH and neurotensin over a broad range of concentrations. These secretagogues also stimulated release of prolactin. Although the coincident incubation of dopamine with these agents resulted in a marked diminution of prolactin release, no concomitant reduction in inositol phosphate production was observed. In addition, bromocriptine, a potent agonist of dopamine, also proved ineffective in blunting stimulated phosphatidylinositol catabolism. Although it slightly inhibited basal rates of inositol tris-, bis- and monophosphate production, these results show that the secretagogue-mediated enhancement of phosphatidylinositol catabolism may be correlated with an increased release of prolactin and that the inhibition of hormone release produced by dopamine is not achieved by reducing basal or secretagogue-mediated inositol phosphate production.
J. Endocr. (1986) 110, 389–393