bluuebunny/crossref_metadata_2025_split huggingface dataset:
TESTOSTERONE Δ4-REDUCTASE ACTIVITY IN RAT LIVER: HORMONAL CONTROL IN VIVO
Authors: PATTERSON D. C. , CLARK A. F. , BIRD C. E. 
Published: December 2008

SUMMARY
The rate-limiting step in the metabolism of testosterone by the liver is reduction of the double bond in ring A. Using a spectrophotometric assay we have studied the effects of some hormonal manipulations on the levels (per mg protein) of testosterone Δ4-reductase activity in rat liver. While the levels of enzyme activity were higher for adult female rat liver than for adult male liver, there were no further changes in livers from female rats at day 15 of gestation. In male rats, castration increased, hypophysectomy decreased and adrenalectomy had no effect on the level of activity. Administration of oestradiol valerate increased the activity in intact and adrenalectomized animals and had no effect in the hypophysectomized or castrated groups. Administration of testosterone enanthate decreased the levels of activity in the castrated and adrenalectomized groups and had no effects in unoperated or hypophysectomized animals. When given together, the two hormones were antagonistic. Prolactin had no significant effects in either intact or hypophysectomized animals. Experiments with actinomycin D and cycloheximide indicated that the synthesis of new protein was involved in the effects of oestradiol in intact rats. All the changes reflected alterations in the microsomal enzyme level.
PERSISTENT RHYTHMS OF PINEAL AND SERUM MELATONIN IN COCKERELS IN CONTINUOUS DARKNESS
Authors: RALPH C. L. , PELHAM R. W. , MACBRIDE S. E. , REILLY DIANE P. 
Published: December 2008

SUMMARY
The melatonin (N-acetyl-5-methoxytryptamine) content of the pineal body and serum of White Leghorn cockerels (Gallus domesticus) appears to vary cyclically, with a higher level of both found at the mid-point of the dark period than at the mid-point of the light period when the animals were kept in a diurnal light cycle. These rhythmic variations persisted, although with an apparently lower amplitude, when the animals were maintained in continuous darkness for 2 weeks. The oscillations appeared to be free-running, circadian rhythms and to be phase-locked with the locomotor activity rhythms of the individual birds studied.
COMPARISON OF PLASMA LEVELS OF LUTEINIZING HORMONE RELEASING HORMONE IN MEN AFTER INTRAVENOUS OR INTRANASAL ADMINISTRATION
Authors: FINK G. , GENNSER G. , LIEDHOLM P. , THORELL J. , MULDER J. 
Published: December 2008

SUMMARY
The concentrations of luteinizing hormone releasing hormone (LH-RH) and luteinizing hormone (LH) were determined by radioimmunoassay in blood samples taken at intervals after the administration of different doses of synthetic LH-RH administered either intravenously or intranasally in healthy fertile men. Intranasal administration of LH-RH caused a dose-dependent increase of plasma LH with the peak occurring later than that after intravenous injection. The intravenous route was approximately 100 times more effective than the intranasal route in terms of the dose of LH-RH necessary to achieve an LH response of similar magnitude, but the route through the nasal mucosa seems a safe and convenient way for LH-RH administration. The characteristics of the disappearance curve, metabolic clearance rate and volumes of distribution of LH-RH in man are compared with those found by others.
INACTIVATION OF OXYTOCIN AND SYNTHETIC OXYTOCIN ANALOGUES BY HEN TISSUES
Authors: BRZEZIŃSKA-ŚLEBODZIŃSKA EWA 
Published: December 2008

SUMMARY
The oxytocin-inactivating activity (OIA) of liver, kidney, uterus, pancreas, spleen and duodenum homogenates of hens was studied. The first-order constant of oxytocin inactivation was higher in the liver and pancreas than in the uterus and kidney or in the duodenum and spleen. Using synthetic analogues of oxytocin (deamino-oxytocin, deamino-carba1-oxytocin and carba1-oxytocin the mechanism of enzymic inactivation of oxytocin by hen tissue was investigated.
Enzymic hydrolysis by the CH2-terminal cleavage was most marked in duodenum (about 86% OIA) and kidney (54·8% OIA). Reduction of the disulphide bridge was most marked in the uterus (about 80% OIA) and pancreas (about 73% OIA). Splitting by non-specific aminopeptidases after reduction of the disulphide bridge occurred mainly in the liver (72% OIA) and in the spleen (44% OIA).
EFFECT OF ACTIVE IMMUNIZATION TO LUTEINIZING HORMONE RELEASING HORMONE ON SERUM AND PITUITARY GONADOTROPHINS, TESTES AND ACCESSORY SEX ORGANS IN THE MALE RAT
Authors: FRASER H. M. , GUNN A. , JEFFCOATE S. L. , HOLLAND DIANE T. 
Published: December 2008

SUMMARY
Autoimmunity to luteinizing hormone releasing hormone (LH-RH) in adult male rats, induced by immunization with LH-RH conjugated to bovine serum albumin, resulted in atrophy of the testes and secondary sex organs and aspermatogenesis. Both immunoreactive luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in serum and the pituitary were reduced to low levels compared with those of control animals. It is suggested that antibodies to LH-RH can inhibit the action of endogenous hormone and that LH-RH is, in fact, the gonadotrophin-releasing hormone in the rat, required for the release of both LH and FSH.
SOME FACTORS AFFECTING THE DETECTION OF LONG-ACTING THYROID STIMULATOR PROTECTOR USING THE McKENZIE BIOASSAY
Authors: DIRMIKIS SUSAN 
Published: December 2008

SUMMARY
The long-acting thyroid stimulator (LATS) protector may be detected by its property of blocking the binding of LATS to LATS absorbing activity (LAA). This study confirmed that the sensitivity of LATS protector detection was largely determined by the choice of reference mixture of LATS and LAA.
Optimal sensitivity was achieved when: (a) the reference concentration of LATS activity gave a response at the upper end of the linear part of the dose–response curve; (b) the reference LATS-containing serum required a minimum of LAA for LATS binding; (c) the reference LAA preparation was free of thyroglobulin; (d) the concentration of LAA in the reference mixture was that which almost abolished the response to the reference concentration of LATS; (e) the reference LAA preparation was incubated with LATS protector before the addition of the reference LATS.
HOMOSEXUAL WOMEN: AN ENDOCRINE AND PSYCHOLOGICAL STUDY
Authors: GRIFFITHS P. D. , MERRY J. , BROWNING MARGARET C. K. , EISINGER A. J. , HUNTSMAN R. G. , LORD E. JENNY A. , POLANI P. E. , TANNER J. M. , WHITEHOUSE R. H. 
Published: December 2008

SUMMARY
Forty-two members of a Lesbian organization volunteered to participate in a study designed to seek organic abnormalities. Urinary levels of oestrone, oestradiol, oestriol, pregnanediol, 17-oxosteroids, 17-hydroxycorticosteroids, testosterone and epitestosterone were determined. No consistent pattern of hormonal abnormality emerged. Thirty-seven of the subjects completed the Eysenck Personality Inventory and 39 completed a questionnaire. The mean neuroticism score for the group was significantly higher and the mean extraversion score was significantly lower than in the normal population. This finding of dysthymia was reflected to some extent by the high incidence of past psychiatric treatment for anxiety and/or depression.
LUTEINIZING HORMONE RELEASE IN ENTIRE AND CASTRATED RAMS FOLLOWING INJECTION OF SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE, AND EFFECT OF TESTOSTERONE PROPIONATE PRE-TREATMENT
Authors: GALLOWAY D. B. , PELLETIER J. 
Published: December 2008

SUMMARY
Plasma luteinizing hormone (LH) levels and LH responses to intravenous administration of 100 μg luteinizing hormone releasing hormone (LH-RH) were studied in entire rams, long-term castrated animals (operation performed six months previously), long-term castrated animals treated with testosterone for the two preceding weeks and short-term castrated animals (castrated 3 h before LH-RH injection). LH was measured by radioimmunoassay in samples taken at 5 or 15 min intervals.
Basal LH levels were lower in entire rams (0·9 ng/ml) than in long-term castrated animals (6·0 ng/ml). After LH-RH treatment the LH response was much smaller (peak level 9·6 ng/ml, total response 13·3 ng/ml/1 h) and slower (120 min to peak) in entire than in long-term castrated animals (peak level 61·8 ng/ml, total response 141·2 ng/ml/1 h, 29 min to peak). Testosterone treatment after long-term castration depressed the basal LH level and delayed the peak LH response after LH-RH to values similar to those for entire rams.
After short-term castration the response to LH-RH was already as great (peak level 70·1 ng/ml, total response 133·6 ng/ml/1 h) as after long-term castration. The latency to peak LH level (82 min) was intermediate between that for untreated and testosterone-treated long-term castrated animals (130 min).
Testosterone treatment was considered to have acted on the hypothalamus to depress basal levels. The results provided evidence for the presence of two inhibitory actions of the testis at the pituitary level in the ram: a qualitative delaying action of testosterone and a quantitative inhibitory action of the testis on LH release after LH-RH injection. The latter may also be related to plasma testosterone levels.
THE TEMPORAL RELATIONSHIP BETWEEN THE SECRETION OF LUTEINIZING HORMONE AND TESTOSTERONE IN MAN
Authors: ROWE P. H. , RACEY P. A. , LINCOLN G. A. , ELLWOOD M. , LEHANE J. , SHENTON J. C. 
Published: December 2008

SUMMARY
It has been suggested recently that testosterone secretion by the human testis may be controlled by factors other than luteinizing hormone (LH). In order to re-examine this hypothesis, plasma LH and testosterone concentrations were determined throughout the day in eight studies. A new method of data analysis revealed that the levels of the two hormones were closely related, but that the testicular response to LH was sluggish. These results explain some inconsistencies in the literature. It was demonstrated that average values for LH varied throughout the day, with a morning maximum and an evening minimum. It was also shown that injections of LH releasing hormone in man resulted in an increase in plasma testosterone above control levels. These results are consistent with the concept that LH controls the major changes in testosterone secretion in men. They do not exclude, however, the possible existence of other factors which might affect the peripheral concentration of testosterone, such as changes in testicular blood flow.
SERUM LEVELS AND BIOCHEMICAL CHARACTERIZATION OF OESTRADIOL-17β DEHYDROGENASE IN UMBILICAL CORD BLOOD
Authors: PLOTTI G. , MENINI E. , BOMPIANI A. 
Published: December 2008

SUMMARY
The properties of the enzyme oestradiol-17β dehydrogenase from human umbilical cord serum have been compared with those of oestradiol-17β dehydrogenase present in the maternal peripheral blood. On the basis of studies on stability, specificity, optimum pH, rate of enzymic reaction and Km determinations it can be concluded that oestradiol-17β dehydrogenase in the umbilical cord arteries has an activity between 5 and 15 times higher than in the umbilical cord vein and about 65% of the activity of the enzyme present in the maternal peripheral blood. The present results strongly suggest that in pregnancy the enzyme oestradiol-17β dehydrogenase is elaborated not only by the placenta but also by the foetus.
INFLUENCE OF OESTROGEN ON THE INITIATION OF NESTING BEHAVIOUR IN FEMALE BUDGERIGARS
Authors: HUTCHISON R. E. 
Published: December 2008

SUMMARY
Intact, breeding female budgerigars enter and occupy a nestbox 8–10 days before egg-laying. Ovariectomized budgerigars did not enter nestboxes. Oestradiol-17β monobenzoate (OB) (0·05 mg, i.m.) induced ovariectomized birds to enter nestboxes. Higher dosages (0·1 or 0·5 mg) did not facilitate this effect. The amount of time spent in nesting behaviour by all OB-treated groups did not differ from that shown by a group of intact females during the initial phase of the nesting sequence (first 4 days in the nestbox), but was significantly less than that of intact females undergoing later stages of nesting behaviour (4 days before and after laying the first egg).
Oestradiol induced an increase in oviduct weight and size which was dose-dependent. With a low dose (0·05 mg OB), the oviducts were slightly larger than those of intact females which had been in the nestbox 1–2 days. With higher dose levels (0·1–0·5 mg OB), precursor albumen granules had formed in tubular glands of the magnum, a stage more typical of females which had been in the nestbox 4–6 days.
The results indicate that low levels of oestrogen induce female budgerigars to enter nestboxes and initiate oviduct development. Subsequent phases of the nesting behaviour and oviduct development may be causally related to other hormones.
INFLUENCE OF ANAESTHETICS, MATING, PREMATURE DELIVERY, THE TIME OF DAY OF BLOOD SAMPLING, AND SUCKLING ON PLASMA LEVELS OF LUTEINIZING HORMONE IN HAMSTERS
Authors: JOSHI H. S. , LABHSETWAR A. P. 
Published: December 2008

SUMMARY
The influence of several factors on immunoreactive LH levels in peripheral plasma of female hamsters was investigated. The LH values for animals anaesthetized with either sodium pentobarbitone or chloral hydrate were significantly lower (P < 0-01) than those values obtained for hamsters sampled under ether anaesthesia.
Mating on the night of pro-oestrus resulted in increased LH levels (P < 0-01) the following morning as compared with the levels in control females not caged with males.
The LH levels were relatively low (13 ± 2 (s.e.m.) ng/ml) on the afternoon (16.00–18.00 h) of day 15 of pregnancy and also on the morning (09.00– 10.00 h) of day 16 before (7 ± 1 ng/ml) and after parturition (4 ± 0·2 ng/ml), but rose severalfold (561 ± 201 ng/ml) on the afternoon post partum.
When premature delivery was induced on day 15 of pregnancy by administration of prostaglandin E2 the LH levels did not rise on the afternoon of this day (29± 11 ng/ml), but did so on the following afternoon (213± 115 ng/ml), at the same interval post coitum as in normal delivery.
Marked increases in the concentration of LH in plasma were observed on the afternoon of each of days 0–6 post partum. The levels were comparable to those found on the afternoon of pro-oestrus in cyclic hamsters and could be blocked by administration of sodium phenobarbitone at 13.00 h. Similar afternoon surges of LH were not observed during dioestrus.
In the morning, the LH levels were significantly higher (P < 0-001) in the non-suckled dams (95 ± 4 ng/ml) than those in mothers allowed to nurse their young (13± 4 ng/ml). In contrast, the levels in the afternoon were unaffected by the suckling stimulus (suckled, 495 ± 76 v. non-suckled, 744± 165 ng/ml; P > 0-05).
METABOLIC CLEARANCE RATE, PRODUCTION RATE AND MAMMARY UPTAKE OF PROGESTERONE IN THE GOAT
Authors: HEAP R. B. , BEDFORD C. A. , LINZELL J. L. 
Published: December 2008

SUMMARY
The dynamics of progesterone uptake and metabolism in the mammary gland of the goat have been measured and related to the metabolic clearance rate and production rate of the hormone determined by tracer kinetic techniques.
The metabolic clearance rate of progesterone from blood was 3·13 ± 0·35 (s.e.m.) 1/min in ten experiments on six goats; values tended to be slightly higher in pregnant than in non-pregnant goats. The production rate of progesterone at oestrus, and at day 3 of the normal cycle, was less than 0·01 μg/min. During the luteal phase of the oestrous cycle the production rate was 8·5 and 14·6 μg/min in 2 animals, and in the second half of pregnancy, 15·3 ± 0·6 μg/min (5 animals).
Progesterone was extracted from the circulation by the mammary gland of conscious goats with an efficiency of 49·4 ± 11·3% in non-pregnant, and 51·7 ± 11·5% in pregnant animals. The mean clearance rate of progesterone by the udder was 0·2791/min, 8·8% of the metabolic clearance rate. Mammary uptake of progesterone in goats with an actively secreting corpus luteum was 0·64 ± 0·29μg/min, which gave an estimated value of 0·11– 1·88 ng/min/g mammary gland.
The mammary extraction of progesterone was investigated in a goat 3 days after oestrus when any high affinity receptor sites would presumably be unoccupied. During the infusion of progesterone into a mammary artery, tissue samples were taken from various organs, including the mammary gland, and the concentration of labelled compounds at steady state was determined. A high mammary extraction of progesterone was found to be attributable principally to progesterone metabolism. The metabolites of progesterone were removed from the gland in venous blood and were not stored to any appreciable extent in mammary tissue.
Experiments in vitro confirmed the findings in vivo that mammary tissue metabolized labelled progesterone and also pregnenolone and androstenedione; metabolism of dehydroepiandrosterone, oestradiol-17β, oestrone and cortisol was relatively small. Confirmation of our previous finding that the mammary gland of the goat can synthesize progesterone from labelled pregnenolone infused into the gland in vivo, further implicates this organ as an active site of metabolism of certain steroids. The physiological role of steroid metabolism in the mammary gland is discussed.
CHANGES IN THE CONCENTRATION OF LUTEINIZING HORMONE IN PLASMA DURING DEVELOPMENT IN THE GUINEA-PIG
Authors: DONOVAN B. T. , TER HAAR M. B. , LOCKHART A. N. , MACKINNON P. C. B. , MATTOCK J. M. , PEDDIE M. J. 
Published: December 2008

SUMMARY
The concentration of LH in the plasma of guinea-pigs from day 50 of gestation to day 45 of postnatal life was assayed by radioimmunoassay utilizing a cross-reaction with anti-ovine LH antiserum. The effect of gonadectomy in infancy and in the adult upon the plasma concentration of LH was also studied.
The LH concentration in the plasma of male or female foetuses was high immediately prenatally and fell at birth. High levels of LH were again detected in male, with a lesser increase in female, guinea-pigs over the first 10 days postnatally. Maternal plasma concentrations of LH remained consistently low. Removal of the gonads on days 0, 5, 10, 15, 25 or 35 of postnatal life, followed by blood collection at autopsy 10 days later, caused a significant rise in plasma LH content at all ages. The rise in plasma LH after gonadectomy in adults was less marked in male than in female guinea-pigs.
BINDING AND METABOLISM OF 5α-ANDROSTANE-3α,17β-DIOL AND OF 5α-ANDROSTANE-3β,17β-DIOL IN THE PROSTATE, SEMINAL VESICLES AND PLASMA OF MALE RATS: STUDIES IN VIVO AND IN VITRO
Authors: KRIEG M. , HORST H.-J. , STERBA M.-L. 
Published: December 2008

SUMMARY
Binding of 5α-androstane-3α,17β-diol (3α-diol) and 5α-androstane-3β,17β-diol (3β-diol) in vivo and in vitro to the 100000 g cytosol fraction of the rat prostate and seminal vesicles as well as to plasma was studied by agargel electrophoresis and sucrose density gradient ultracentrifugation and the results compared with the corresponding findings for 5α-dihydrotestosterone (5α-DHT). The metabolism of 3α-diol and 3β-diol was also investigated by thin-layer chromatography. The following results were obtained: (1) A specific binding of 3α-diol and 3β-diol by the cytosols could not be demonstrated in vitro, while 5α-DHT was specifically bound. (2) In plasma, 3α-diol was extensively bound, 3β-diol less extensively bound, while 5α-DHT remained unbound. (3) After intravenous injection of 3α-diol, specifically bound radioactivity, increasing within 30 min, was found in the prostate cytosol, while after 3β-diol injection no binding occurred. (4) Parallel to the increased binding, the total radioactivity in the prostate accumulated within 30 min after 3α-diol injection, the uptake being 5·3 times higher than in skeletal muscle. However after 3β-diol injection, total radioactivity decreased in the prostate within 30 min, the uptake being only 1·5 times higher than in skeletal muscle. (5) One minute after injection of 3α-diol, 53% of the extracted radioactivity in the prostate had been converted to 5α-DHT, this increased within 30 min to 81%. Thirty minutes after the injection of 3β-diol, about 32% of the extracted radioactivity in the prostate had been converted to 5α-DHT. (6) From the in-vivo and in-vitro experiments it was concluded that 3α-diol exerts its biological effects mainly by its conversion into 5α-DHT.
INFLUENCE OF PROSTAGLANDINS AND HUMAN CHORIONIC GONADOTROPHIN ON PROGESTERONE CONCENTRATION AND OOCYTE MATURATION IN MOUSE OVARIAN FOLLICLES MAINTAINED IN ORGAN CULTURE
Authors: NEAL P. , BAKER T. G. , McNATTY K. P. , SCARAMUZZI R. J. 
Published: December 2008

SUMMARY
The response of mouse ovaries maintained in organ culture to prostaglandin E2 (PGE2) and prostaglandin F2α (F2α) was assessed using quantitative histological and radioimmunoassay procedures.
Prostaglandin E2 induced histological changes in the cultured follicles comparable to those induced by human chorionic gonadotrophin (HCG) and the increase in the number of oocytes undergoing preovulatory maturation over the control value was the same irrespective of the treatment (PGE2 alone, HCG alone, or PGE2 + HCG). The amount of progesterone/ ml of culture medium was also significantly higher with these preparations than in control cultures (about 125 ng/ml compared with 57 ng/ml).
By contrast, 5 μg PGF2α/ml medium increased neither the number of oocytes undergoing maturation nor the concentration of progesterone in the culture medium. The latter increased when the dose of PGF2α was increased to 30 μg/ml, although the proportion of oocytes beyond the dictyate stage remained at the control level. There was no augmentation in the response (above the level for HCG alone) when HCG and PGF2α were added to the explant medium simultaneously. These results are discussed in terms of the possible mechanism of action of the various preparations.
INHIBITORY ACTION OF OESTROGEN ON CALCIUM-INDUCED MITOSIS IN RAT BONE MARROW AND THYMUS
Authors: SMITH G. R. , GURSON MOLLY L. , RIDDELL A. J. , PERRIS A. D. 
Published: December 2008

SUMMARY
In the male rat injections of CaCl2 and MgCl2 stimulated mitosis in bone marrow and thymus tissue. The magnesium salt was also mitogenic in the normal female, but calcium only exerted its mitogenic effect after ovariectomy. Oestradiol, but not progesterone replacement therapy abolished calcium-induced mitosis in the ovariectomized rat. The inability of calcium to stimulate cell division was also apparent in the thyroparathyroidectomized female rat, suggesting the oestradiol blockade did not operate via some indirect action on the calcium homeostatic hormones calcitonin or parathyroid hormone.
When thymic lymphocytes derived from male or female rats were isolated and maintained in suspension, increased calcium or magnesium concentrations in the culture medium stimulated the entry of cells into mitosis. Addition of oestradiol to the culture medium abolished the mitogenic effect of increased calcium levels, but had no effect on magnesium-induced proliferation. These experiments suggested that oestradiol might act at the cell surface to prevent the influx of calcium but not magnesium ions into the interior of the cell and thus to block the sequence of biochemical events which lead to the initiation of DNA synthesis and culminate in mitosis.