bluuebunny/crossref_metadata_2025 huggingface dataset:
TESTOSTERONE IN RETE TESTIS FLUID AND BLOOD OF RAMS AND RATS
Authors: COOPER T. G. , WAITES G. M. H.
Published: December 2008

Rete testis fluid (RTF) was collected from six conscious Clun Forest rams by cannulation of the efferent ducts, and from anaesthetized rats by cannulation of the rete testis 16–24 h after efferent duct ligation. Testosterone concentration in this fluid was measured by radioimmunoassay and compared with levels in blood collected from the subcapsular testicular artery and veins and spermatic and jugular veins.

The testosterone concentration in ram RTF fluctuated from nondetectable (< 100 pg/ml) levels to approximately 20 ng/ml over 1–25 h collection periods. The mean concentration was 8·5 ± 1·2 (s.e.m.). This value was approximately one fifth the mean concentration of testosterone in samples from the testicular veins at the dorsal pole of the testis.

Testosterone concentration (ng/ml) in rat RTF collected under sodium pentobarbitone anaesthesia was 26·4 ± 2·7 (18 measurements, 18 rats). A lower value was obtained when ether was the anaesthetic used during efferent duct ligation (ether, 20·3; halothane, 29·9; sodium pentobarbitone, 29·1). The mean concentration of testosterone in the RTF was similar to that in testicular venous blood (29·8 ± 3·9; 27 measurements, 27 rats), although the highest values were obtained after ether anaesthesia (ether, 38·3; halothane, 29·0; sodium pentobarbitone, 21·7).

Testosterone concentration in the testicular arterial inflow was similar to that in jugular venous blood in the ram but exceeded carotid arterial levels in the rat.

The values reported are used to discuss: the origin and significance of androgens in rete testis fluid, species differences, the effect of anaesthetics and season, and vascular exchange of testosterone in the spermatic cord.
PROTEIN AND RNA SYNTHESIS IN HUMAN PROLIFERATIVE ENDOMETRIUM IN ORGAN CULTURE AND THE EFFECT OF PROGESTERONE
Authors: SHAPIRO S. S. , HAGERMAN D. D.
Published: December 2008

Tissue concentrations of glycogen and incorporation of leucine and uridine were measured after short-term organ culture of human endometrium. Higher concentrations of glycogen and an increased rate of incorporation of leucine were found in tissue from cultures treated with oestrogen and progesterone when compared with tissue from cultures treated with oestrogen alone. No detectable difference in uridine incorporation was observed in these experiments.
PROLACTIN RELEASE AND LACTOGENESIS AFTER OVARIECTOMY IN PREGNANT RATS: EFFECT OF OVARIAN HORMONES
Authors: VERMOUTH NELIA T. , DEIS R. P.
Published: December 2008

Ovariectomy of rats on day 19 of pregnancy induced a rapid rise in serum prolactin. Levels were significantly increased 4 h after removal of the ovaries and continued to rise up to 24 h. A transient fall occurred at 32 h, but serum prolactin concentration was still raised after 36, 48 and 58 h. Similar increases of serum prolactin occurred after ovariectomy on days 17 and 18 of pregnancy. Lactogenesis occurred 24·8 or 28·2 h after ovariectomy on days 19 or 17–18 of pregnancy respectively. Rats ovariectomized on day 17 or 18 delivered on day 21 and rats ovariectomized on day 19 delivered on day 22 of pregnancy. Ovariectomy impaired parturition in all groups. Treatment with oestrogen immediately after the operation did not prevent the rise in serum prolactin levels 4, 8 and 12 h after ovariectomy, but 24 h after ovariectomy, prolactin values were not significantly different from those in sham-operated control rats. When oestrogen was injected 12 h after ovariectomy, serum prolactin was markedly increased 12 h later. Lactogenesis occurred about 22·9 h after oestrogen treatment and all animals delivered on day 21 of pregnancy. Progesterone treatment prevented the rise in prolactin levels observed 4 and 8 h after ovariectomy, but at 12 h levels had risen and were similar to those observed in untreated ovariectomized rats. Progesterone prevented lactogenesis for 14 h (around 37.5 h after ovariectomy) and induced a delay in the onset of parturition. The results indicate that the decrease of progesterone in the blood after ovariectomy in pregnant rats may induce a release of prolactin and lactogenesis. Oestrogen seems to be effective in raising prolactin levels at low blood concentrations of progesterone.
ARTIFICIAL INDUCTION OF LACTATION IN EWES
Authors: FULKERSON W. J. , McDOWELL G. H.
Published: December 2008

Lactation was induced in non-pregnant, intact ewes. The injection of 60 mg progesterone plus 240 μg oestradiol benzoate every third day for 60 days increased udder size. Subsequent daily injection of 10 mg dexamethasone trimethylacetate or 5 mg oestradiol benzoate plus 12·5 mg progesterone for 6 days led to further udder development and initiated secretion of fluid similar in appearance and composition to normal ovine milk.

Both treatments were equally effective in initiating milk secretion and subsequent production (approximately 0·50 kg/day) was similar to that of ewes lactating after normal pregnancy [0·59 ± 0·06 (s.e.m.) kg/day]. Glands of ewes receiving no treatment other than milking after oestrogen and progesterone priming remained small in size and produced only trivial volumes of secretion when milked out daily for 14 days.
TESTOSTERONE Δ4-REDUCTASE ACTIVITY IN RAT LIVER: HORMONAL CONTROL IN VIVO
Authors: PATTERSON D. C. , CLARK A. F. , BIRD C. E.
Published: December 2008

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
CONCENTRATIONS OF CYCLIC AMP IN RABBIT OVARIAN TISSUE DURING THE PREOVULATORY PERIOD AND PSEUDOPREGNANCY AFTER INDUCTION OF OVULATION BY ADMINISTRATION OF HUMAN CHORIONIC GONADOTROPHIN
Authors: GOFF A. K. , MAJOR PATRICIA W.
Published: December 2008

Concentrations of cyclic AMP were measured in rabbit ovaries at various times after injection of an ovulatory dose of human chorionic gonadotrophin (HCG). A biphasic increase in cyclic AMP concentration occurred during the preovulatory period, with peaks 30 min and 3–4 h after HCG injection. Concentrations of cyclic AMP had returned to those observed in ovaries of control oestrous animals before the onset of ovulation 10–12 h after administration of HCG, and remained low throughout the period of pseudopregnancy. Concentrations of cyclic AMP in the newly formed and developing corpora lutea were similar to the concentrations observed in the remainder of the tissue during this period. No significant increase in cyclic AMP concentration was observed 7–9 days after initiation of ovulation. Concentrations of ATP were also investigated during the preovulatory period. The dose– response relationship of HCG to cyclic AMP production in oestrous rabbit ovaries was investigated.
SEX-DEPENDENT PREPUBERTAL GONADOTROPHIN SURGES IN THE RAT
Authors: ENEROTH PETER , GUSTAFSSON JAN-ÅKE , SKETT PAUL , STENBERG ÅKE
Published: December 2008

The concentrations of LH and FSH were measured by radioimmunoassay in sera from immature male and female rats of various ages. Fairly high levels of FSH were found in both sexes at birth but LH was not detected. FSH peaks appeared in the male at 13 and 19 days of age and in the female at 13 and 17–19 days of age. LH was undetectable in the male before 12 days of age, rose to a peak (440 ± 60 (s.d.) ng/ml) at 13 days of age and fell below the detection level again between 15 and 25 days of age. A further increase then occurred which almost reached adult levels. LH was first detectable in the female rat at 11 days of age with a peak value of 130 ± 35 ng/ml at 12 days. The hormone was undetectable on days 14 and 15, rose to a second peak on day 18 (148 ± 56 ng/ml), and was again absent between 19 and 25 days of age. The concentration rose, as in the male, between days 25 and 28 to a level similar to that of the adult. The results show sexual differences in prepubertal gonadotrophin surges.

The LH peak at 12–13 days in both sexes appears to be light-dependent. The FSH peak at this time was affected by light but was not strictly light-dependent.
INFLUENCE OF THE PITUITARY GLAND ON INSULIN SECRETION IN THE GENETICALLY OBESE (ob/ob) MOUSE
Authors: BELOFF-CHAIN ANNE , EDWARDSON J. A. , HAWTHORN JANET
Published: December 2008

The influence of the pituitary gland of lean and genetically obese (ob/ob) mice on insulin secretion from microdissected pancreatic islets of lean and ob/ob mice has been studied by perifusing the pituitaries of these animals in series with the isolated islets and measuring insulin secretion at 5-min intervals over a period of 60 min.

It has been shown that the pituitary perifusate of both lean and obese mice stimulate insulin secretion from lean mouse islets but not from obese mouse islets. The maximum stimulation occurs in the first 10 min and with the lean mouse pituitaries returns to the basal level in about 20 min, whereas with the obese mouse pituitaries insulin secretion is about double that from the control islets even after 40 min.

A concentration of pure porcine ACTH equivalent to about three times the amount released from the pituitary gland under the experimental conditions used, caused only a small stimulation of insulin release. Possible interpretations of these findings and further lines of investigation are discussed.
EFFECTS OF ELECTRICAL STIMULATION OF THE NEUROHYPOPHYSIS ON LABOUR IN THE RAT
Authors: BOER K. , LINCOLN D. W. , SWAAB D. F.
Published: December 2008

Labour was studied in 69 primiparous and multiparous rats by continuous observation and by the recording of intra-uterine activity. The effect of electrical stimulation of the neurohypophysis with stimulation parameters selected to create a pulsatile release of oxytocin was investigated. Stimulation was applied to the neurohypophysis through chronically implanted electrodes every 5 min, in 45 min sessions, from noon on Day 21 of gestation and at 3 h intervals thereafter.

Electrical stimulation successfully promoted (or induced) the onset and facilitated the course of labour. Stimulation at 12.00 h on Day 21, or at a subsequent stimulation session 3, 6, 9 or more hours later, promoted an immediate increase in the frequency and amplitude of uterine contractions. Overt signs of abdominal straining followed within 5–30 min and the first pup was delivered shortly thereafter. These 'induced' deliveries were almost identical to those displayed by control rats; labour continued to completion despite the termination of the stimulation session after 45 min. By contrast, one third of the stimulated animals displayed an interrupted pattern of labour in which events virtually ceased for 30–60 min when stimulation was terminated. Stimulation, however, only advanced labour by 1–2 h in relation to control animals; this was not statistically significant.

Stimulation accelerated the delivery of the first 5 pups in each litter. In both stimulated and control animals, the birth intervals declined over these first few deliveries to reach the lowest values of 5–6 min throughout the remainder of labour. The most common litter size was 12 pups.

The distribution of labour on Day 21 and 22 was bimodal. Seventy per cent of the animals gave birth between 12.00 and 18.00 h on Day 21, a few gave birth during the following night and the remainder formed a second peak on Day 22. All litters of less than 6 pups were born during this later period.

The implications of these results in the context of spontaneous labour are discussed. We conclude that endogenous oxytocin (with perhaps other neurohypophysial hormones) released in pulses of 1–3 mu. every 5 min can promote a pattern of labour on Day 21 of gestation that is almost indistinguishable from that which occurs naturally.
MODIFICATION OF RAT UTERINE MONOAMINE OXIDASE ACTIVITY BY STEROID HORMONES
Authors: GROSSO D. S. , GAWIENOWSKI A. M.
Published: December 2008

The monoamine oxidase (MAO) activity in the ovariectomized rat uterus was significantly increased above control levels in animals given testosterone: 33% (P < 0·01) with tryptamine or 34% (P < 0·05) with tyramine as substrate. Activity was also higher in hydrocortisone-treated animals: 30% (P < 0·05) with tyramine or 25% (P < 0·05) with tryptamine as substrate. Progesterone injection increased MAO activity toward tyramine by 20% but towards tryptamine by only 8%. The differences are not statistically significant but are believed to be real since they were reproducible. MAO activity in oestradiol-treated animals was 11% less than in the controls for both substrates. Although they are not significant differences, they were reproducible. No change in MAO activity was observed in the cerebellum, hypothalamus or anterior pituitary of ovariectomized rats after steroid treatment. At oestrus the enzyme activity in the uterus was lower than at dioestrus or prooestrus when β-phenylethylamine was the substrate. When 5-hydroxytryptamine was used to measure enzyme activity, the same values were found at oestrus, dioestrus and prooestrus. Ovariectomy did not cause any changes in MAO activity in any of the tissues. Effects of the steroids in vivo were probably not due to a direct action on the enzyme since only at high concentrations did they have any effect on the mitochondrial enzyme activity of the uterus in vitro.
RESPONSIVENESS OF THE OVARY TO GONADOTROPHINS IN PRE- AND PERINATAL LIFE: OESTROGEN SECRETION IN TISSUE AND ORGAN CULTURES
Authors: LEVINA S. E. , GYÉVAI A. , HORVÁTH E.
Published: December 2008

Secretion of oestrogen by the ovaries of foetal (15–19 days of gestation) and newborn rats in organ and tissue culture was not detectable by fluorometry when the ovary was taken from foetuses before folliculogenesis had occurred. In organ cultures of ovaries, the time of folliculogenesis corresponded with the normal timing of folliculogenesis in vivo. In tissue cultures the process of formation of follicles was delayed.

Oestrogens were present in the medium when folliculogenesis was fully established in the cultured foetal ovaries. Secretion began spontaneously and did not depend on the addition of gonadotrophins to the medium. The addition of gonadotrophins to the culture medium did not affect the level of oestrogen secreted by the foetal and newborn rat ovaries during the period of incubation (2–3 weeks).
SYNTHESIS AND SECRETION OF A LARGE GLYCOPROTEIN IN THE PARS INTERMEDIA
Authors: HOPKINS C. R.
Published: December 2008

The biosynthesis, intracellular transport and release of [3H]leucine-containing secretory product has been followed in the pars intermedia of Xenopus laevis and, in particular, the synthesis and secretion of a large molecular weight glycoprotein secretory product was demonstrated. However, if Xenopus adrenocorticotrophin does contain a leucine residue the results obtained provided no support for the view that it serves as a precursor for melanocyte-stimulating hormone in this species.
ASPECTS OF ADRENAL FUNCTION IN THE DOMESTIC FOWL
Authors: CULBERT J. , WELLS J. W.
Published: December 2008

Chromatographic purification of extracts of hen peripheral plasma on Florisil columns before measurement by spectrofluorometry showed a basal level for corticosterone of 1–3 μg/100 ml, which is much lower than concentrations previously reported using acid fluorescence. Neither handling, restraint nor repeated bleeding affected the concentration of this hormone or of glucose.

Adrenal function tests with two preparations of synthetic corticotrophin showed that they caused a rapid rise in blood corticosterone and eventually of glucose. Results of studies using insulin or tolbutamide i.v. suggest that there is a threshold concentration of plasma glucose (about 70 mg/100 ml) below which hypoglycaemia stimulates the hypothalamic-pituitary-adrenal system in fowls.

Prolonged treatment of laying hens with protamine zinc insulin led to aphagia and cessation of egg-laying; increased concentrations of corticosterone were observed 2 days after the administration of insulin ceased, coinciding with the return to normal plasma levels of glucose.

'Chemical adrenalectomy' with metyrapone showed that the restoration of plasma glucose to a normal concentration after insulin treatment is dependent upon fully functional adrenal cortical tissue. It appears likely that the adrenal medulla is a target for corticosterone which probably regulates the tissue levels of phenylethanolamine-N-methyltransferase, one of the enzymes necessary for the biosynthesis of adrenaline.
SYNTHESIS OF DEHYDROEPIANDROSTERONE AND DEHYDROEPIANDROSTERONE SULPHATE BY THE HUMAN ADRENAL
Authors: DOOUSS T. W. , SKINNER S. J. M. , COUCH R. A. F.
Published: December 2008

The role of pregnenolone sulphate in adrenal steroid biosynthesis and the ability of the human adrenal gland to synthesize and secrete dehydroepiandrosterone (DHA) and dehydroepiandrosterone sulphate (DHA sulphate) was investigated. The presence of pregnenolone sulphate and DHA sulphate was demonstrated by measuring their concentrations in human adrenal tissue. Pregnenolone sulphate was metabolized in vitro mainly to free steroids, including DHA and cortisol, as well as directly to DHA sulphate in some cases. Similar results were obtained upon perfusion of the adrenal gland in situ with [14C]pregnenolone and [3H]pregnenolone sulphate as the substrates and isolating the metabolites from the adrenal venous blood. Dehydroepiandrosterone sulphate was derived mainly from the sulphation of free DHA. The hydrolysis of DHA sulphate did not appear to make a significant contribution to the amounts of DHA synthesized under these conditions.

The adrenal secretion of DHA and DHA sulphate by eight patients undergoing adrenalectomy was determined by measuring the concentrations of these compounds in samples of adrenal and peripheral venous blood taken simultaneously. In one patient secretion of DHA and DHA sulphate was equivalent whilst in the remainder there was much greater secretion of DHA.
SERUM LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE CONCENTRATIONS IN IMMATURE FEMALE RATS TREATED WITH MULTIPLE INJECTIONS AND VARIOUS AMOUNTS OF LUTEINIZING HORMONE RELEASING HORMONE
Authors: JOHNSON D. C. , MALLAMPATI R. S.
Published: December 2008

Release of immunoreactive LH and FSH was induced in immature intact female rats by repeated injections of synthetic luteinizing hormone releasing hormone (LH-RH). Altering the dose of LH-RH (5, 10, 20, 50 ng) and the frequency of administration (every 10, 20, 30 or 60 min) over a period of 2 h produced a variety of serum LH and FSH concentrations and ratios. When the dose was a constant 20 ng but the frequency of injections was either 20 or 30 min, a steady state in serum gonadotrophin concentrations was reached within 1 h and the level remained the same during the second hour. When given every 10 min, 20 ng LH-RH produced a much higher concentration of both LH and FSH during the second hour of stimulation. Examination of the gonadotrophin levels after each injection of LH-RH showed that the pituitary response was variable in spite of a constant stimulus.
EFFECT OF THYROIDECTOMY ON THE ACTIVITY OF α-GLUCOSIDASES AND ACID HYDROLASES IN THE SMALL INTESTINE OF RATS DURING WEANING
Authors: KOLDOVSKÝ OTAKAR , JUMAWAN JOCELYN , PALMIERI MICHAEL
Published: December 2008

Adrenalectomy performed on 14-day-old rats delayed the usual increase of sucrase and maltase activity as well as the decrease of acid β-galactosidase, β-glucuronidase and N-acetyl-β-glucosaminidase activity during the third postnatal week. Since these changes were only delayed, the role of the thyroid was explored. Thyroidectomy performed simultaneously with adrenalectomy on 14-day-old rats did not influence the increase in body weight and growth of the small intestine (already slowed down by adrenalectomy), but caused a further substantial delay in the maturation of the enzyme profile of the small intestine. Our results indicate that the thyroid is involved in regulation of the hydrolases studied.
EFFECTS OF CASTRATION AND GONADAL STEROIDS ON SERUM LUTEINIZING HORMONE AND PROLACTIN IN OLD AND YOUNG RATS
Authors: SHAAR C. J. , EUKER J. S. , RIEGLE G. D. , MEITES J.
Published: December 2008

Changes in serum LH and prolactin concentrations in response to bilateral gonadectomy and gonadal steroid replacement were measured in mature young (4–6 months) and old (23–30 months) female and male Long–Evans rats. On day 13 after gonadectomy, female rats were injected with oestradiol benzoate (OB) and male rats with testosterone propionate (TP) for a period of 12 days. They were then permitted a recovery period of 6 weeks. Serum prolactin and LH concentrations were measured by radioimmunoassay in single blood samples taken at various intervals before and after gonadectomy and during and after steroid treatment.

Serum LH levels were about the same in intact young and old female rats, but after ovariectomy LH rose several fold higher in young than in old female rats. In male rats, serum LH values were about four times greater in intact young than in intact old rats, and after orchidectomy the increase in serum LH was greater in young than in old rats. Oestradiol benzoate and TP injections into female and male young and old rats produced variable effects on LH release. Serum prolactin concentrations were approximately six times higher in old intact than in young intact female rats, and after ovariectomy showed a much greater percentage reduction in old than in young female rats. Administration of OB produced a greater absolute increase in serum prolactin in old than in young female rats. Serum prolactin values were about the same in old and young male rats, and the effects of castration and TP administration on serum prolactin were not markedly different in the two age groups. These results indicate that old female and male rats are less capable of releasing LH than young rats of both sexes, but old females release more prolactin than young females.
RESPONSE OF ISOLATED RABBIT ARTICULAR AND EPIPHYSEAL CHONDROCYTES TO RAT LIVER SOMATOMEDIN
Authors: ASH PATRICIA , FRANCIS M. J. O.
Published: December 2008

Isolated rat liver, when perfused with medium containing bovine growth homone produced somatomedin-like activity (liver somatomedin).

Liver somatomedin is useful in studies of the hormonal control of the cartilage plate in vitro, since unlike serum it is not contaminated with other hormones or growth factors (apart from growth hormone). Chondrocytes isolated from various regions of the growth cartilage responded differently to liver somatomedin; proliferative chondrocytes, like those isolated from the articular cartilage, showed increased [3H]thymidine uptake in response to liver somatomedin, whereas hypertrophic chondrocytes did not respond. It is suggested that there is a reduction in the response to somatomedin by growth plate chondrocytes as they pass from the proliferative to the hypertrophic state.

Thyroxine, thought to be involved in the processes of hypertrophy and new bone formation, did not directly affect [3H]thymidine uptake by proliferative chondrocytes, but inhibited stimulation of their activity by liver somatomedin.

Measurement of [3H]thymidine uptake by isolated articular chondrocytes may provide a useful assay for both liver and serum somatomedin. The graded response of chondrocytes to increasing concentrations of liver somatomedin paralleled the response to increasing levels of serum somatomedin.
EFFECTS OF STEROID HORMONES ON DEVELOPING MOUSE SKIN IN VITRO
Authors: SINGH AMREEK , HARDY MARGARET H.
Published: December 2008

Pieces of skin from 13·5- to 15-day-old foetal mice were grown in organ culture in a biological medium with or without the addition of hormonal steroids. Cortisol (7·5 μg/ml) caused thinning of the non-cornified epidermis and flattening of the stratum granulosum after 3 days. By 6 days the epidermis was thinner and hair follicles were regressing, and these changes continued up to 12 days. Administration of corticosterone (5 μg/ml) also produced thinning of the epidermis and regression of the follicles after 6 days.

Good differentiation of epidermis and hair follicles was obtained when testosterone (100 μg/ml) was added to the medium. The non-cornified epidermal layers were similar to those of control cultures at 3 days but less than half as thick at 6 days. Hair follicles differentiated as rapidly in medium containing testosterone as in normal medium, but, unlike in the latter medium, also developed sebaceous gland anlagen at 6 days. Some explants in testosterone medium showed signs of sebaceous cell differentiation at 9 days.
CALCITONIN, PARATHYROIDECTOMY AND MODELLING OF BONES IN THE GROWING RAT
Authors: WHALEN J. P. , KROOK L. , MACINTYRE I. , NUNEZ E. A.
Published: December 2008

After calcitonin injection, parathyroidectomy, or both, in young growing rats, broadening of the proximal femoral metaphysis with lack of normal concavity of the medial and lateral contours was observed radiographically. Histologically, this abnormal modelling was associated with retarded osteocytic osteolysis. Further manifestations of decelerated resorption included retention and extension of the chondroid core in the secondary spongiosa, retention of cartilage in the cortex and a large increase in the number of cementing lines.