bluuebunny/crossref_metadata_2025_split huggingface dataset:
THYROID ACTIVITY AND OXIDATIVE METABOLISM IN A SPECIES OF GECKO (HEMIDACTYLUS FLAVIVIRIDIS RÜPPELL) IN RELATION TO SEX HORMONES
Authors: CHANDOLA ASHA , KUMAR D. SURESH , THAPLIYAL J. P. 
Published: December 2008

SUMMARY
Orchidectomy in Hemidactylus flaviviridis led to significant reduction of thyroidal 131I uptake, thyroidal content of thyroxine, plasma protein-bound iodine and oxygen consumption of isolated liver and skeletal muscle (at 30 °C). Administration of testosterone to orchidectomized lizards restored these parameters to normal levels. Dependence of thyroid function and oxidative metabolism on male hormone may be a general feature in reptiles. This hormone may, therefore, be of greater physiological importance in these animals than in other vertebrates. Since reptiles occupy a crucial phylogenetic position in the animal kingdom these findings are important from the point of view of evolution of the functional aspects of hormones in vertebrates.
The results also show that thyroid function is inhibited by oestrogen(s) in this lizard. This may be an adaptive compensatory measure to control (through effects of the thyroid on metabolic activities) the extra expenditure of energy usually associated with such energy-consuming functions as ovulation and egg-laying.
THE SITE OF SECRETION OF ANDROSTENEDIONE IN NON-PREGNANT WOMEN
Authors: BAIRD D. T. , BURGER P. E. , HEAVON-JONES G. D. , SCARAMUZZI R. J. 
Published: December 2008

SUMMARY
The site of secretion of androstenedione in women was investigated by measuring the concentration of androstenedione in peripheral and ovarian venous plasma by radioimmunoassay at different stages of the menstrual cycle. The concentration in peripheral plasma rose from 1·45 ± 0·11 (s.e.m.) ng/ml on day 1 to a peak on the 7 days around mid-cycle (2·29 ± 0·08) before declining gradually during the luteal phase. The concentration of androstenedione in plasma draining ovaries containing the pre-ovulatory follicle or a corpus luteum (33·2 ± 9·0) was significantly higher than in plasma draining the contralateral ovary (10·1 ± 1·6, P < 0·001). In women in whom ovulation was induced with gonadotrophins the concentration of androstenedione in peripheral plasma rose from 1·42 ± 0·21 before treatment to reach maximum levels (2·5–4·5 ng/ml) in the luteal phase. There was a significant (P < 0·001) correlation between the concentration of androstenedione and oestradiol-17β in peripheral (r = 0·50) and ovarian (r = 0·79) venous plasma. These findings indicate that all three cellular compartments in the ovary secrete significant amounts of androstenedione in women during their reproductive life.
OESTROGEN AND THE CONTROL OF GONADOTROPHIN SECRETION IN THE IMMATURE RAT
Authors: DÖCKE F. , DÖRNER G. 
Published: December 2008

SUMMARY
Experiments were performed in female Wistar rats on the mode of action of oestrogen in affecting gonadotrophin secretion during infancy. Using an improved implantation method, former findings on a hypophysial site of oestrogen action in the Hohlweg effect were confirmed. The sensitivity to the ovulation-inducing effect of oestradiol benzoate (OB) increased as the rats approached the age of natural puberty. The first spontaneous ovulation could be suppressed by intrahypophysial, but not by intrahypothalamic, progesterone implants.
A single s.c. injection or intracranial administration of OB at 25 or 26 days of age, although leading to premature vaginal opening (VO) and, in some of the animals, to one ovulation, did not induce true precocious puberty. To accelerate the onset of puberty, 0·05 μg OB/100 g body wt had to be injected daily from 5 days of age to VO, or from day 5 to day 10 and, additionally, from day 26 to VO. After long-term oestrogen treatment, the gonadotrophin-inhibiting effect of OB implanted into the middle hypothalamus from 26 to 34 days of age was significantly reduced in comparison with untreated control rats. A final experiment demonstrated that the first ovarian cycle was not prolonged after neonatal ovariectomy and implantation of ovaries at 24, 28 or 32 days of age. The results indicate that similar neurohormonal mechanisms are operational at the first pubertal and at later cyclic ovulations. They also indicate that the maturation of the gonadotrophin-controlling mechanisms continues during infancy in the absence of ovarian steroids. It can be accelerated in Wistar rats by long-term, but not by short-term prepubertal oestrogen treatment.
CIRCADIAN PERIODICITY AND STRESS RESPONSIVENESS OF THE PITUITARY–ADRENAL SYSTEM OF RATS AFTER CENTRAL ADMINISTRATION OF 6-HYDROXYDOPAMINE
Authors: KAPLANSKI J. , VAN DELFT A. M. L. , NYAKAS C. , STOOF J. C. , SMELIK P. G. 
Published: December 2008

SUMMARY
Injection of 250 μg 6-hydroxydopamine (6-OHDA) into the lateral ventricle of adult male and female rats resulted 1 week later in: (1) a lowered brain content of noradrenaline to 20% and dopamine to 40–50% that of control levels but no change in brain serotonin content; (2) a slight reduction in male and no change in female body weight; (3) no change in adrenal weight; (4) minor or no changes in diurnal pituitary–adrenal periodicity or in the responsiveness of this system to ether stress, laparotomy or exposure to a strange environment and handling. Dexamethasone blockade of the diurnal rise in adrenocortical activity was also unchanged.
Intracerebral administration of 200 μg 6-OHDA to newborn male and female rats in three sequential doses of 40, 60 and 100 μg, resulted at 12 weeks of age in (1) a lowered brain content of noradrenaline and dopamine to 10% that of control levels but no change in brain serotonin; (2) a 30% decrease in body weight; (3) no change in adrenal weight; (4) minor or no changes in pituitary–adrenal periodicity nor in the responsiveness to ether stress and exposure to a strange environment and handling.
When minor changes after 6-OHDA treatment of adult or neonatal rats were found, they always pointed to a stimulatory function of brain catecholamines in pituitary–adrenal activity. It is concluded however that a severe and chronic depletion of brain catecholaminergic systems has no important consequences for the normal functioning of the pituitary–adrenal system.
PLASMA CONCENTRATIONS OF CORTISOL IN HYPOPHYSECTOMIZED AND SODIUM CHLORIDE-ADAPTED GOLDFISH (CARASSIUS AURATUS L.)
Authors: PORTHÉ-NIBELLE JACQUELINE , LAHLOU BRAHIM 
Published: December 2008

SUMMARY
Plasma cortisol concentrations, measured by competitive protein-binding, were examined in intact and hypophysectomized goldfish (Carassius auratus L.) adapted to fresh water or to 210 mm-sodium chloride solutions. The mean plasma cortisol concentration of freshwater-adapted fish (6·6 ± 1·8 (s.e.m.) μg/100 ml plasma) increased after stress and intraperitoneal injections of mammalian corticotrophin. Hypophysectomy resulted in a reduction in plasma cortisol concentration to about 2 μg/100 ml plasma.
Transfer of fish to sodium chloride solutions caused rapid, but transitory increases in the plasma cortisol concentrations in intact, but not in hypophysectomized fish. After 3 days in the sodium chloride solution the cortisol levels were similar to those of control fish kept in fresh water. The plasma concentrations of this corticosteroid in goldfish appear to be unrelated to external salinity, although a 'mineralocorticoid' action of the hormone cannot be excluded.
CHANGES IN THE CONCENTRATIONS OF CORTISOL AND CORTICOSTERONE IN THE PLASMA AND ADRENAL GLANDS OF THE GUINEA-PIG FROM BIRTH TO WEANING
Authors: DALLE M. , DELOST P. 
Published: December 2008

SUMMARY
Concentrations of cortisol and corticosterone in the plasma and adrenal glands of male and female guinea-pigs were estimated throughout the first postnatal day and thereafter at intervals up to 3 weeks of age. In the guinea-pig, the basal level of cortisol secretion is established more slowly than in other species. The concentration of plasma cortisol is very high at birth, with a marked fall between days 1 and 10 post partum and then a steady level from day 10 to 20, the time of weaning. At day 10 the values for plasma cortisol and corticosterone approach the lower ones found in the adult. There were peaks in the amounts of corticosteroids found in the adrenal gland at 50 h, 4 and 7 days and these may have been due to increased hormonal synthesis between days 2 and 8.
STEROIDOGENESIS IN VITRO BY THE OVARIAN TISSUE OF THE DOMESTIC FOWL (GALLUS DOMESTICUS)
Authors: NAKAMURA TAKAO , TANABE YUICHI , KATUKAWA HIDEO 
Published: December 2008

SUMMARY
Ovaries excised from 5- and 7-month-old laying hens were homogenized. The homogenates were incubated separately with 4-14C-labelled pregnenolone, progesterone, 17α-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, testosterone, oestrone and oestradiol, and [7-3H]17αhydroxypregnenolone in the presence of NAD+ or NADPH under aerobic conditions. The homogenates synthesized progesterone, 17αhydroxyprogesterone, 17α-hydroxypregnenolone, dehydroepiandrosterone, androstenedione, testosterone, pregnanedione, 17α-hydroxy-5β-pregnane3,20-dione, 5β-androstane-3,17-dione, 19-hydroxyandrostenedione, 19hydroxytestosterone, oestrone, oestradiol and other minor metabolites. However, the rates for the conversion of androstenedione to oestrone and that of testosterone to oestradiol were low, and after 120 min incubation, the yields were 3·0 and 1·2%, respectively. The results indicate possible involvement of metabolic pathways both from Δ5-C21 steroid to Δ4-C21 steroid and from Δ5-C21 steroid to Δ5-C19 steroid in the formation of androgen by the ovary of the domestic fowl.
EFFECT OF OESTRADIOL-17β AND PROGESTERONE ON THE METABOLISM OF TESTOSTERONE BY HUMAN PROSTATIC TISSUE
Authors: JENKINS J. S. , McCAFFERY V. M. 
Published: December 2008

SUMMARY
The metabolism of testosterone in vitro by normal benign hyperplastic and carcinomatous prostatic tissues has been compared. 5α-Dihydrotestosterone was the predominant metabolite followed by 3α- and 3β-androstanediol. No difference in the pattern of metabolism, either quantitatively or qualitatively, was found in normal, benign hyperplastic and welldifferentiated carcinomatous prostatic tissue. In poorly differentiated carcinomatous tissue there was less formation of all 5α-reduced metabolites. Treatment of patients with carcinomata with diethylstilboestrol resulted in greatly decreased activity of prostatic 5α-reductase with a considerable proportional increase in 17β-dehydrogenase activity. The addition of oestradiol-17β or stilboestrol in vitro also inhibited the formation of 5αdihydrotestosterone and androstanediols by all types of prostatic tissue, but only when high concentrations of oestrogen were used and there was no increase in 17β-dehydrogenase under these conditions. In contrast, progesterone was a much more effective inhibitor of 5α-reductase in vitro than was oestrogen.
BINDING OF HUMAN CHORIONIC GONADOTROPHIN BY RAT TESTIS: EFFECT OF SEXUAL MATURATION, CRYPTORCHIDISM AND HYPOPHYSECTOMY
Authors: FROWEIN JOACHIM , ENGEL WOLFGANG 
Published: December 2008

SUMMARY
The specific binding of 125I-labelled human chorionic gonadotrophin (HCG) by rat testicular homogenate as compared with isolated Leydig cells differs with respect to total binding capacity but not to the dissociation constant (KD) as revealed by Scatchard analysis. The maximal binding capacity for [125I]HCG of crude testicular homogenate was 95 ng/g rat testis. Hypophysectomy causes a decline in binding capacity within the first three days but on the 20th and 30th day after hypophysectomy the relative binding capacity no longer differs from that of controls. Binding capacity is enhanced in cryptorchid testes relative to normal, and increases during sexual maturation to a peak shortly before puberty.
ADRENOCORTICOTROPHIN AND THE DEVELOPMENT OF INSULIN SECRETION IN THE RABBIT FOETUS
Authors: JACK P. M. B. , MILNER R. D. G. 
Published: December 2008

SUMMARY
Foetal rabbits were injected with adrenocorticotrophin (ACTH), decapitated, or decapitated and injected simultaneously with ACTH or cortisol in utero on day 24 of gestation. The foetuses were killed after Caesarian section on day 29, and blood was collected for measurement of plasma insulin concentration and pancreatic tissue was obtained for incubation in physiological buffer. Insulin release from the pancreatic tissue of decapitated foetuses was significantly greater than that from the pancreas of control litter-mates when incubated in media containing 3·3 mm-glucose, 16·5 mm-glucose or 16·5 mm-glucose plus 5 μg glucagon/ml, but was similar when the incubation medium contained 3·3 or 16·5 mm-glucose plus 1 mm-theophylline or 3·3 mm-glucose plus 60 mm-potassium. The pancreata of decapitated or intact foetuses injected with ACTH did not differ significantly from control foetuses in terms of insulin release in response to glucose in vitro. The plasma insulin concentration of decapitated foetuses and decapitated foetuses injected with ACTH was raised, whereas that of intact foetuses injected with ACTH was similar to that of the control foetuses. Cortisol injection at the time of decapitation resulted in a high rate of foetal mortality.
The results indicate that foetal ACTH or foetal adrenocortical secretion influences the normal development of glucose-mediated insulin secretion in the rabbit and that exogenous ACTH corrects the effect of decapitation on β cell function in vitro but not on plasma insulin concentration.
EPISODIC RELEASE OF LUTEINIZING HORMONE IN THE DOMESTIC FOWL
Authors: WILSON SUSAN C. , SHARP P. J. 
Published: December 2008

SUMMARY
Plasma luteinizing hormone (LH) levels were measured by radioimmunoassay in serial samples taken from intact adult cockerels, gonadectomized fowl of both sexes and laying hens. By sampling at 30 and 10 min intervals, it was shown that in cockerels LH is released episodically. Each secretory episode lasted 90–120 min and was characterized by a 100–200% rise in LH levels over a period of 10–15 min followed by a more gradual, exponential decline. Mean plasma LH levels were found to be depressed in cockerels as a result of the handling associated with taking blood samples; in cases where LH levels were most depressed, an episodic pattern of secretion could not be demonstrated.
In the gonadectomized fowl, an episodic pattern of LH secretion was shown when blood samples were taken at 10 or 5 min intervals. During each secretory episode, which lasted 20–45 min, LH levels rose by 20–60%. It is suggested that the increase in mean plasma LH levels in gonadectomized fowl (30–77 ng/ml) over those in cockerels (7–16 ng/ml) is related to an increase in the frequency of the episodic release of the hormone. Episodic discharges of LH could not be demonstrated in laying hens. In these birds the mean LH levels are low (1·5–2·4 ng/ml) and consequently may be maintained by secretory episodes which are of too low an amplitude to be detectable.
EFFECTS OF TESTOSTERONE AND PROLACTIN OR GROWTH HORMONE ON THE ACCESSORY SEX ORGANS OF CASTRATED MICE
Authors: KEENAN E. J. , THOMAS J. A. 
Published: December 2008

SUMMARY
In 5-day experiments, neither bovine prolactin (300 or 600 i.u./kg) nor ovine growth hormone (25 i.u./kg) alone significantly enhanced accessory sex organ weights in the castrated mouse. Seminal vesicle weights, and to a lesser extent anterior prostate gland weights, were augmented by the simultaneous injection of testosterone (1·5 mg/kg) daily plus prolactin or growth hormone. The effect was greater than that produced by testosterone alone.
The levels of fructose in accessory sex organs used to indicate androgenic activity were similar in castrated mice receiving testosterone alone or in combination with prolactin or growth hormone. Prolactin alone did not influence uptake of [3H]testosterone by the seminal vesicles or anterior prostate gland over a 5 min period in vivo.
EFFECTS OF CASTRATION, AND TESTOSTERONE IN VITRO, ON THE HYPOTHALAMIC SYNTHESIS OF DIFFERENT PEPTIDE FRACTIONS
Authors: MOGUILEVSKY J. A. , ENERO M. A. , SZWARCFARB B. , DOSORETZ D. 
Published: December 2008

SUMMARY
The incorporation of [3H]tyrosine ([3H]tyr) into different hypothalamic peptide fractions isolated from normal and castrated rats on a Sephadex G-25 column has been studied in vitro. Luteinizing hormone releasing factor (LH-RF) activity was determined in the different fractions by measuring their ability to elicit release of radioimmunoassayable luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in ovariectomized rats treated with oestrogen and progesterone.
For further purification, the fraction with LH-RF activity was applied to a CM-Sephadex G-25 column eluted with a gradient of ammonium acetate. The large radioactive peptides emerged from the Sephadex G-25 column in fraction S-1, while the small peptides with LH-RF activity were eluted in fraction S-2. Gonadectomy significantly increased the incorporation of [3H]tyr into the peptides of fractions S-2. Only in the purified fraction with LH-RF activity was the radioactivity incorporated higher in gonadectomized than in normal rats. The enhanced incorporation in fraction CM-3 observed after castration implies an increase in the hypothalamic synthesis of peptides with LH-RF activity. The addition of testosterone (2 μg/ml) to the incubation medium of hypothalamus from gonadectomized rats, corrected these modifications.
Gonadectomy decreased the incorporation of tyrosine into the large peptides, and incubation with testosterone corrected this change.
The modifications in the incorporation of [3H]tyr into the large and small peptides produced by castration appear to indicate that gonadectomy, as well as stimulating the production of LH-RF, enhances the synthesis of other hypothalamic peptides while inhibiting the synthesis of proteins. On the other hand an increase in the breakdown of large peptides into small peptides cannot be excluded.
STUDIES ON THE BINDING OF 125I-LABELLED CORTICOTROPHIN TO ISOLATED RAT ADRENOCORTICAL CELLS
Authors: McILHINNEY R. A. J. , SCHULSTER D. 
Published: December 2008

SUMMARY
Isolated adrenocortical cells, prepared by collagenase disaggregation of normal rat adrenal glands, have been used to study the binding characteristics of 125I-labelled corticotrophin (ACTH) of established biological activity. The binding of the labelled hormone to these whole cells was highly specific, only peptides possessing steroidogenic activity displaced the labelled hormone. Binding was rapid, being complete within 5 min of adding the hormone, and the amount of hormone bound remained constant for up to 20 min thereafter. Over the range 160–10000 pg ACTH/ml, increased binding of the hormone was observed at all concentrations of hormone which stimulated steroidogenesis. However at levels of ACTH which stimulated maximal steroidogenesis there was no saturation of binding. This provides the first direct evidence for the existence of 'spare receptors' for ACTH on whole adrenocortical cells. Scatchard analysis of the binding data suggests that there are two types of receptor for ACTH in this preparation of cells. One receptor is of high affinity (dissociation constant = 2·5 × 10−10 mol/l) about 3000 sites/cell and the other is of lower affinity (dissociation constant = 1 × 10−8 mol/l) with about 30000 sites/cell.
THE SECRETION AND METABOLIC CLEARANCE RATES OF OESTRADIOL IN THE RAT
Authors: TAPPER C. M. , BROWN-GRANT K. 
Published: December 2008

SUMMARY
The secretion rate (SR) of oestradiol in rats at different stages of the oestrous cycle was determined by measuring the concentration of this hormone in ovarian vein plasma by a competitive protein binding method utilizing rabbit uterine cytosol. The plasma metabolic clearance rate (MCRP) for oestradiol was determined in groups of rats of the same strain and housed under the same conditions by giving a single intravenous injection of tritiated oestradiol-17β and measuring the rate of disappearance of labelled hormone from the plasma. From the relationship SR = MCRP × plasma concentration, predicted values for the plasma oestradiol concentration were obtained and shown to be close to those obtained by direct analysis of peripheral plasma.
The MCRP for oestradiol was not greatly influenced by the stage of the oestrous cycle, the dose of oestradiol-17β injected, ovariectomy 18 h previously or by a sham-operation immediately before the injection of labelled hormone. The anaesthetic used did affect the MCRP; the value for adult female rats injected under ether anaesthesia was about 970 ml/h but under Avertin anaesthesia clearance rates of about 1500 ml/h were obtained. Ligation of the bile duct acutely reduced the MCRP but functional nephrectomy had no immediate effect. Sub-total hepatectomy 18 h previously reduced the MCRP considerably. A small decrease in MCRP was observed when the labelled hormone was administered in third trimester human pregnancy plasma and the MCRP was lower in rats on Day 14 of pregnancy than in rats examined during the oestrous cycle.
PITUITARY HORMONE SECRETION IN THE GENETICALLY MALE RAT PSEUDOHERMAPHRODITE
Authors: GOLDMAN A. S. , ROOT A. W. , DUCKETT G. , SHAPIRO B. H. 
Published: December 2008

SUMMARY
Pituitary content or concentration of follicle-stimulating hormone (FSH), prolactin and growth hormone in the genetically androgen insensitive male rat pseudohermaphrodite is intermediate between normal male and female rats, while pituitary luteinizing hormone (LH) concentration and serum FSH levels are the same as in the normal male. The concentration of serum LH, prolactin and growth hormone indicates no sexual dimorphism. Although the pseudohermaphrodite is genetically male with a female phenotype, our results suggest some degree of masculinization of the hypothalamicpituitary system.
SEASONAL FACTORS AFFECTING THE RELEASE OF PROLACTIN IN GOATS IN RESPONSE TO MILKING
Authors: HART I. C. 
Published: December 2008

SUMMARY
An investigation has been carried out in goats of the possible seasonal factors which might influence the autumn decline in the average concentration of prolactin released at milking. Serial blood samples were taken during milking, once a month between August and December 1972, from groups of mated, non-mated and ovariectomized goats and also from goats maintained in summer light conditions (17 h light: 7 h darkness). Since high levels of progesterone occur in the circulation during the major part of the oestrous cycle and pregnancy in the goat, the same sampling procedure was carried out earlier in the year (June–August) in animals which had been implanted with progesterone tablets.
Although high levels of progesterone in the circulation inhibited the release of prolactin at milking, oestrus, mating and pregnancy were not found to be responsible for the fall in prolactin levels in the blood in the autumn. In each of these cases the concentration of prolactin released at milking decreased uniformly between August and October. Housing goats in summer lighting conditions, however, maintained the release of prolactin at milking at a consistently high level from August until December, but had no effect on the milk yield which declined in a manner similar to that of the control animals. It is concluded that daylength is the predominant factor governing the autumn decline in the concentration of prolactin released at milking and that the decline is not the major cause of the fall in milk production during late lactation in goats.