bluuebunny/crossref_metadata_2025_split huggingface dataset:
STABILITY OF THE THIRD INTERNATIONAL STANDARD FOR CORTICOTROPHIN: ACCELERATED DEGRADATION STUDY USING DIFFERENT BIOASSAYS AND ISOELECTRIC FOCUSING
Authors: STORRING P. L. , GAINES-DAS ROSE E. , TIPLADY R. J. , STENNING BRIDGET E. , MISTRY Y. 
Published: December 2008

The corticotrophin activity of ampoules of the Third International Standard for Corticotrophin (IS) kept at 20 and 37 °C for 15 years was compared with that of ampoules of the IS stored under normal conditions (−20 °C in the dark), using adrenal ascorbate depletion assays after subcutaneous administration of the hormone, assays of an increase in plasma corticosterone after intravenous administration of the hormone and in-vitro adrenal cell corticosterone production assays. Estimates of activity by all three methods are homogeneous and give combined weighted geometric means (with 95% confidence limits), as per cent of the activity in the IS stored at −20 °C, of 92·1 (84·8–100) and 77·8 (71·6–84·5) for the 20 and 37 °C degradation samples respectively.
Isoelectric focusing studies of the ampoule contents of the three preparations showed that ampoules of the IS stored at 20 and 37 °C contained 90 and 79% respectively, of the component representing native corticotrophin found in the IS. These estimates of corticotrophin content are comparable to the estimates of biological activity of these preparations.
The stability of the IS was calculated from the combined bioassay data assuming that degradation follows first order kinetics. The predicted half-life for the activity of the IS is 2800 years with an approximate lower 95% confidence limit of 500 years; the predicted activity of the IS remaining now, after 20 years at −20 °C, is 99·5% of the original activity with an approximate lower 95% confidence limit of 97·3%
INVOLVEMENT OF INHIBIN IN THE REGULATION OF FOLLICLE-STIMULATING HORMONE CONCENTRATIONS IN PREPUBERTAL AND ADULT, MALE AND FEMALE RATS
Authors: HERMANS W. P. , VAN LEEUWEN E. C. M. , DEBETS M. H. M. , DE JONG F. H. 
Published: December 2008

Administration of steroid-free bovine follicular fluid (bFF), containing inhibin-like activity, depressed levels of FSH measured 4 h after injection in intact adult and 35-day-old female rats, but not in younger females. Suppression of FSH was also observed in intact male rats, aged 55 days, but not in older and younger male rats. Eight hours after injection of bFF, FSH levels were depressed in 15-day-old and older immature and adult rats of both sexes. Male and female rats, gonadectomized 2 days earlier, responded similarly to bFF treatment as did the intact animals.
In a second experiment it was found that the rise of FSH levels, occurring within 8 h of gonadectomy, decreased with age in male and increased with age in female rats. Steroid treatment was found to prevent the rise in FSH levels partially in 15-day-old male and completely in 25-day-old female rats, whereas treatment with bFF was fully effective in blocking the FSH rise in both immature and adult rats of both sexes.
It is concluded that inhibin might be a major physiological factor in a fast-acting control of FSH concentrations from at least the age of 25 days onwards in female rats. In male rats its physiological significance might be limited to the prepubertal period, despite the fact that pituitary secretion of FSH is suppressed by exogenous inhibin-like activity at all ages studied.
INCREASE IN THE RESPONSE TO ADRENOCORTICOTROPHIN OF ISOLATED MATERNAL ADRENAL CELLS FROM SHEEP IN LATE PREGNANCY
Authors: GLICKMAN J. A. , PATRICK J. E. , CHALLIS J. R. G. 
Published: December 2008

Adrenal cells were prepared from non-pregnant (anoestrous) sheep, from ewes at days 50, 100 and 130 of pregnancy and at term, and from animals at 1–5 days post partum. The ability of the cells to respond to adrenocorticotrophin (ACTH1–24), α-melanocyte-stimulating hormone (α-MSH), or combinations of these peptides has been examined in vitro. There was a progressive rise in the basal output of cortisol during pregnancy and in the absence of adrenocorticotrophin the cortisol output from adrenal cells of late pregnant and post-partum sheep was significantly greater than that from the non-pregnant animals. Adrenocorticotrophin increased cortisol output by adrenal cells at all times tested. In anoestrous sheep the amount of ACTH required to produce half the maximum output of steroid (ED50) was 8 pg/ml. The ED50 increased in early pregnancy to 112 pg/ml and then fell to < 5 pg/ml between day 100 and term. At term both the stimulation ratio and the absolute increment in cortisol output elicited by a maximal concentration of ACTH were greater than at any other time tested in pregnant or non-pregnant sheep. Cortisol output during pregnancy was not increased by α-MSH, although at term the stimulatory effect of ACTH1–24 was partially antagonized by α-MSH.
These results suggest that there may be an increase in the responsiveness of the maternal adrenal during pregnancy, although the factor(s) responsible remains unknown.
EFFECTS OF ADRENALECTOMY ON REPRODUCTION IN THE MOUSE
Authors: WHITE BARBARA M. , GIDLEY-BAIRD A. A. , EMMENS C. W. 
Published: December 2008

Survival of mice treated with sesame seed oil after adrenalectomy was very low and suggested no beneficial effect, whereas treatment with progesterone improved the chances of survival. Treatment with desoxycorticosterone acetate (DOCA) and methyl prednisolone acetate also increased the number of animals surviving after adrenalectomy. The corticosteroids were significantly more effective in ensuring survival than was progesterone. There was no significant difference in survival between mice receiving a single injection of 10 mg DOCA and those being given an injection of 1·0 mg DOCA per day for 3 days after the operation. To ensure minimum interference of exogenous corticosteroid with the experimental investigation, animals routinely received only a single injection of 1·0 mg DOCA after the operation.
The chance of survival after adrenalectomy was higher in pregnant than in non-pregnant mice. There was a significant linear increase in survival during the first 5 days of pregnancy. Progesterone and prolactin both appeared to be involved in increasing the chance of survival in adrenalectomized pregnant mice.
Adrenalectomy had no effect on the number of mice mating and ovulating. Adrenalectomized mice were apparently having normal cycles and 4 weeks after adrenalectomy they were able to mate and ovulate. Compensatory ovulation was seen in hemi-ovariectomized mice and was not abolished by adrenalectomy. Implantation was also unaffected by the operation.
STIMULATION OF CORTISOL SECRETION IN VITRO FROM THE INTERRENAL TISSUE OF THE CICHLID FISH, SAROTHERODON AUREUS, BY ADRENOCORTICOTROPHIN OR CYCLIC AMP
Authors: ILAN Z. , YARON Z. 
Published: December 2008

A superfusion system was developed in which secretion of cortisol from the interrenal tissue of Sarotherodon aureus could be stimulated by ACTH. Head kidneys from four fish were cut into fragments and superfused with Eagle's basal medium containing 4 mm-NaHCO3 and bovine serum albumin (50 mg/100 ml). The superfused medium was collected every 15 min before stimulation and every 5 min thereafter. Cortisol was measured in the medium by radioimmunoassay. The rate of cortisol secretion increased considerably after a 5 min pulse of 0·1 mu. porcine ACTH/ml, reaching a peak of 11·64 ± 2·40 (s.e.m.) ng/min (n = 5) after 20 min. In the subsequent 35 min the secretion rate decreased to a level of 0·49 ± 0·21 ng/min which was within the range of the baseline (0·2–0·7 ng/min). The amount of cortisol secreted by the superfused tissue in response to the corticotrophin, calculated from the area under the peak, was dose-dependent at the range of 0·06–273 mu. ACTH.
Cortisol secretion in this system could also be stimulated by a crude pituitary extract from the same fish. Using the dose–response line, the adrenocorticotrophic activity in the pituitary gland of S. aureus was estimated as 0·2 i.u./g or 1·87 mu. per gland, in porcine ACTH equivalents.
It was possible to substitute ACTH with dibutyryl cyclic AMP. The response of the interrenal tissue, i.e. the increase in secretion of cortisol, was dose-dependent at the range of 2–20 mmol/l. The response of the superfused interrenal tissue to ACTH could be extended by the addition of the synthetic phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (0·1 mmol/l), to the medium. These results indicated that the stimulation of cortisol secretion from the interrenal tissue of this fish by ACTH is, most probably, mediated by cyclic AMP as a second messenger.
EFFECT OF ADMINISTRATION OF DOPAMINERGIC AGONISTS ON THE UTERINE RESPONSIVENESS TO OESTROGEN IN MATURING RATS
Authors: HERNANDEZ D. E. , ALVAREZ E. O. 
Published: December 2008

The purpose of the present work was to investigate whether the administration of a dopamine agonist (2-bromo-α-ergocryptine) was able to interfere with the normal change in uterine sensitivity to oestrogen that occurs around the onset of puberty in the rat.
To determine the change in uterine sensitivity groups of rats at 25, 30 or 35 days of age were killed (to find the initial uterine weight) or ovariectomized with or without oestrogen replacement therapy (0·05 μg/100 g body wt, daily for 5 days) and then killed to determine the final uterine weight. Comparisons were made between initial and final uterine weights. Five days before the animals reached 25, 30 or 35 days of age, one group was injected with 2-bromo-α-ergocryptine (0·5 mg/100 g body wt daily for 5 days) and another one with solvent (control rats). At the ages specified (25, 30 and 35 days of age) both groups were subjected to the ovariectomy schedule. Results showed that the bromocriptine treatment was effective in blocking the normal uterine change in sensitivity that occurs at 30 days of age. At 35 days of age the dopamine agonist was able to counteract the action of oestrogen in maintaining the uterine weight 5 days after ovariectomy. The results are interpreted as suggesting that the mechanism of change in uterine responsiveness to oestrogen in maturing rats is mediated by prolactin.
PROTEIN COMPOSITION OF THE THYROID COLLOID IN PATIENTS WITH HYPERTHYROIDISM
Authors: ANDERBERG B. , ENESTRÖM S. , GILLQUIST J. , SMEDS S. 
Published: December 2008

Analysis of the protein composition of the thyroid colloid was performed in 28 patients operated on for hyperthyroidism. Fifteen of the patients were treated before the operation with carbimazole combined with thyroxine and 13 were treated with propranolol alone. Colloid was collected by micropuncture of single follicles in peroperative thyroid biopsies. The protein composition was analysed by microgel electrophoresis and densitometry, both in the colloid samples and in the supernatant fraction of homogenates of microbiopsies from the thyroid specimens.
The analyses showed that, during treatment with carbimazole and thyroxine, the relative amount of the larger thyroglobulin aggregates (S-TG) was decreased compared with the relative amount observed in the colloid from normal thyroid tissue. In the hyperfunctioning thyroid tissue from the propranolol-treated patients the protein composition of the colloid was similar to that observed in normal tissue and the relative amount of the S-TG fractions was significantly higher than in the carbimazole- and thyroxine-treated group.
It may be concluded that the increased release of thyroid hormones in hyperthyroidism is not combined with changes in the protein composition of the thyroid colloid. The decreased relative amount of the S-TG fractions in the thyroid colloid from patients treated with carbimazole and thyroxine was probably due to an insufficient capacity to iodinate thyroglobulin.
DELAY OF OVULATION IN RATS WITH SODIUM PENTOBARBITONE: APPARENT DIFFERENCES BETWEEN RATS WITH 4- OR 5-DAY REPRODUCTIVE CYCLES
Authors: VAN DER SCHOOT P. 
Published: December 2008

In rats with 4- or 5-day reproductive cycles various responses to the blockade of ovulation with sodium pentobarbitone at pro-oestrus (or at pro-oestrus and on the next day) were compared. The blood concentrations of oestradiol decreased rapidly during the 24 h period after injection of sodium pentobarbitone at pro-oestrus in rats with 5-day cycles. In those with 4-day cycles this response took almost a day to develop. Injection of sodium pentobarbitone at pro-oestrus and on the next day interfered with ovulation of the present crop of large follicles in rats with 5-day cycles. In 4-day cyclic rats this procedure delayed ovulation of these follicles by 48 h. Receptive behaviour was absent on the day after the second injection of sodium pentobarbitone in rats with 5-day cycles; some receptivity was, however, induced by the injection of gonadotrophin. The latter injection resulted in the release of a low number of eggs; fertilization of these eggs, however, did not occur. In 4-day cyclic rats receptive behaviour was recorded on the day after the second injection of sodium pentobarbitone: fertilization of delayed ovulated eggs took place normally but pregnancy was seen only rarely.
The results indicated clear differences in responses to blockade of ovulation with sodium pentobarbitone between rats with 4- or 5-day cycles. The differences most probably result from a more advanced 'age' of preovulatory follicles at pro-oestrus of 5-day cycles compared with those of 4-day cycles. Experimental delay of ovulation reveals ageing changes and the probable onset of atresia at an earlier time after blockade in 5-day cyclic than in 4-day cyclic rats.
MECHANISM(S) BY WHICH ADRENALECTOMY AND CORTICOSTERONE INFLUENCE PROLACTIN RELEASE IN THE RAT
Authors: LEUNG F. C. , CHEN H. T. , VERKAIK S. J. , STEGER R. W. , PELUSO J. J. , CAMPBELL G. A. , MEITES J. 
Published: December 2008

The possible direct effect of corticosterone on release of pituitary prolactin was examined in a system using incubation for 8 h. Corticosterone at either 0·1 or 1 μg/ml medium had no significant effect on in-vitro prolactin release but 10 or 100 μg/ml medium produced a significant inhibition of release of prolactin. Release of LH, FSH and thyroid-stimulating hormone were not altered by 0·1, 1 or 10 μg corticosterone/ml, indicating that its action at the concentration of 10 μg/ml was specific on release of prolactin. Corticosterone injected at doses of 1 or 5 mg/kg into hypophysectomized rats with two pituitary grafts underneath the kidney capsule produced a significant fall in serum levels of prolactin when compared with control hypophysectomized rats with two pituitary grafts. Examination with the electron microscope showed that about one third of the lactotrophes from adrenalectomized rats after corticosterone injection exhibited patterns which suggested a decrease in protein synthesis when compared with lactotrophes from adrenalectomized rats given only the vehicle injection. These observations indicated that inhibition of release of prolactin by corticosterone could be exerted directly on the pituitary gland, and that the rise of serum levels of prolactin after adrenalectomy might have been due to the removal of direct inhibition by corticosterone.
Male rats were adrenalectomized and 2–3 weeks later, concentrations of dopamine and noradrenaline in the medial basal hypothalamus were measured and found not to be different from values in intact rats. Dopamine metabolism also was not altered in the median eminence. The dopaminergic agonist, l-DOPA, inhibited, and the antagonists, pimozide and haloperidol, stimulated release of prolactin in both adrenalectomized and intact rats. Serotonin (5-HT) metabolism in the medial basal hypothalamus and anterior hypothalamus of adrenalectomized rats was not significantly different from values in intact rats, but a higher concentration of 5-HT was observed in the medial basal hypothalamus of adrenalectomized rats when compared with the values in intact rats. A serotonergic agonist, fluoxetine, and an antagonist, cyproheptadine, had no apparent effect on release of prolactin in intact rats, but fluoxetine produced a significant rise, and cyproheptadine, a significant lowering of serum levels of prolactin in adrenalectomized rats. These results suggest that 5-HT, but not dopamine, may be involved in the rise of prolactin after adrenalectomy.
PANCREATIC β-CELL FUNCTION IN THE FETAL FOAL AND MARE
Authors: FOWDEN ABIGAIL L. , BARNES R. J. , COMLINE R. S. , SILVER MARIAN 
Published: December 2008

Insulin secretion and the factors influencing β-cell function were investigated in the chronically catheterized fetal foal and mare during the second half of gestation. The response of the fetal β cells to exogenous glucose was also examined. The mean concentration of insulin in the fetal foal was 7·5 ± 0·5 (s.e.m.) μu./ml (n = 20) which was significantly less than the corresponding maternal value of 49·0 ± 5·0μu./ml (n = 20, P<0·01). The insulin concentration in non-pregnant horses was 24·5 ± 1·5 μu./ml (n = 5) which was significantly less than the value in the pregnant animals (P<0·01). However, there was no significant difference in the mean glucose concentration between the groups of adult animals.
The insulin concentration was related to the endogenous glucose level in both adult and fetal horses. Wide variation in the maternal insulin concentration was observed above a glucose concentration of about 5·0 mmol/l. The mean concentration of insulin in pregnant mares decreased with increasing gestational age while the mean glucose concentration remained unaltered throughout the second half of gestation. There was no change in the basal concentrations of insulin or glucose in the fetus with gestational age although the fetal β-cell response to exogenous glucose appeared to increase with increasing fetal age after 270 days of gestation (term 330 days). There was a significant arterio-venous difference in the concentration of insulin across the gravid uterus in the mare when the arterial insulin level was greater than 30 μu./ml. Below this value, there was no consistent uptake of insulin by the uterus. The observations are discussed in relation to the regulation of insulin release in utero and the effects of pregnancy on maternal β-cell function.
INITIATION OF FOLLICULAR MATURATION AND OVULATION AFTER REMOVAL OF THE LITTER FROM THE LACTATING RAT
Authors: TAYA KAZUYOSHI , SASAMOTO SHUJI 
Published: December 2008

In order to elucidate the mechanism of the resumption of follicular activity and ovulation in rats, levels of FSH, LH and prolactin in plasma and pituitary gland and ovarian follicular development were quantified after removal of the litter on day 3 of lactation (day of parturition = day 0 of lactation). Such removal resulted in ovulation of 13 oocytes 4 days later, a number comparable with that found in normal cyclic rats. Plasma levels of prolactin were high during lactation but markedly decreased after removal of the litter. Although plasma concentrations of FSH and LH did not change during days 3–7 of lactation, there was an FSH surge between 24 and 30 h after removal of the litter. Plasma concentrations of LH also increased slightly but significantly by 24 h after removal of the litter and this value persisted during the following 2 days. Surges of FSH, LH and prolactin occurred at 17.00 h 3 days after pups were removed. Removal of the litter did not increase pituitary contents of FSH, LH and prolactin and a marked reduction in pituitary levels of FSH and LH, but not of prolactin, occurred at 17 00 h 3 days after removal of the litter.
A quantitative study of follicular development indicated that follicles larger than 401 μm in diameter were absent during days 3–7 of lactation. However, the number and size of antral follicles increased by 30 h after removal of the litter, probably due to the increases in plasma levels of FSH and LH, and follicles larger than 601 μm in diameter appeared 3 days after the young were removed. Although ovulation could not be induced by human chorionic gonadotrophin from days 3 to 5 of lactation, its administration 30 h after removal of the litter produced ovulation in all rats by the following morning.
These results indicated that a moderate increase in FSH, although below the amounts released at the preovulatory surge, together with basal levels of LH which were within the range observed on the day of dioestrus during the normal cycle were responsible for the initiation of follicular maturation after removal of the litter.
VARIATIONS IN PLASMA CONCENTRATIONS OF α-MELANOCYTE-STIMULATING HORMONE DURING THE OESTROUS CYCLE OF THE RAT AND AFTER ADMINISTRATION OF OVARIAN STEROIDS
Authors: THODY A. J. , WILSON C. A. , LUCAS P. D. , FISHER C. 
Published: December 2008

Plasma concentrations of α-melanocyte-stimulating hormone (α-MSH) were measured by radioimmunoassay at various times during the oestrous cycle of the rat. Variations in plasma α-MSH concentrations occurred throughout the oestrous cycle. Plasma α-MSH concentrations were low during the day of dioestrus 1 and rose during the evening reaching peak levels at around 02.00 and 06.00 h on dioestrus 2. Plasma α-MSH concentrations then fell and remained low throughout the rest of dioestrus 2. A different pattern was observed during pro-oestrus and oestrus. On those days peak α-MSH concentrations occurred during the morning and persisted until the onset of the dark period at around 17.00 h.
Plasma α-MSH concentrations in ovariectomized rats were found to be increased 24 h after administration of a single injection of oestradiol benzoate and at 12 and 36 h after a single injection of progesterone. It is suggested that these ovarian steroids may influence the rhythm in plasma α-MSH concentration that occurs during the oestrous cycle.
COMPARISON OF BINDING OF BOVINE AND HUMAN THYROID-STIMULATING HORMONE TO RECEPTOR SITES ON HUMAN THYROID MEMBRANES
Authors: KERMODE J. C. , THOMPSON B. D. , EDMONDS C. J. 
Published: December 2008

The binding of 125I-labelled bovine TSH (bTSH) to a wide range of human thyroid membrane preparations was compared with that of 125I-labelled human TSH (hTSH). Much higher binding percentages were obtained with the 125I-labelled bTSH. This was because the receptors had a higher binding affinity for bTSH than for hTSH. No differences in tracer purity, nor differences in optimal conditions for the binding of bTSH or hTSH, nor tracer degradation contributed significantly to the better binding of 125I-labelled bTSH.
Good correlation was found between binding percentages for 125I-labelled bTSH and 125I-labelled hTSH over the range of thyroid specimens. Useful information on human TSH receptors is, therefore, obtainable from binding studies with 125I-labelled bTSH.
The TSH displacement curves yielded linear Scatchard plots whenever the tracer and displacing hormones were of the same species. The data were, therefore, consistent with a simple binding reaction between TSH and a single set of independent receptor sites.