bluuebunny/crossref_metadata_2025 huggingface dataset:
UPTAKE OF [6,7-3H]OESTRADIOL-17β BY NORMAL AND ABNORMAL HUMAN ENDOMETRIUM
Authors: CROCKER S. G. , MILTON P. J. D. , KING R. J. B.
Published: December 2008

Cytoplasmic and nuclear oestradiol-17β binding sites have been measured in human endometrium obtained at different stages of the menstrual cycle and from patients with cystic hyperplasia and endometrial carcinoma. In normal endometrium both sets of sites are maximal at about the time of ovulation. The number of nuclear sites obtained by incubating endometrium with oestradiol-17β in vitro paralleled the number of available cytoplasmic sites.

Cytoplasmic and nuclear binding sites were present in cystic hyperplasia and endometrial carcinomata. There was no correlation between the degree of differentiation of the tumour and its oestradiol-17β binding capacity. All types of endometrium contained variable amounts of 8–10 S and 4–5 S cytoplasmic receptors. The proportions of these receptors were not affected by the presence of the protease inhibitor, p-phenylmethylsulphonyl fluoride.
IMPLANTATION OF OESTROGEN IN THE BRAIN AND THE INDUCTION OF OVULATION IN THE GUINEA-PIG
Authors: BOOTH JANET E. , DONOVAN B. T.
Published: December 2008

In the guinea-pig, when bilateral oestrogen implants were placed in the medial basal hypothalamus, anterior hypothalamus or suprachiasmatic area on day 10 of the oestrous cycle, ovarian changes indicative of gonadotrophin secretion were observed on day 15. Similarly located cholesterol implants and oestrogen implants outside this region were without effect. The gonadotrophin release was likely to have been induced by an action of the steroid at the hypothalamic, rather than the pituitary level, since bilateral implants of oestrogen in the pars distalis caused ovarian activation in only one out of eight animals. Signs of normal ovulation were evident in only three out of 19 animals in which oestrogen was implanted in the medial basal hypothalamus on day 10 and left in place for 10 days. The ovaries of some other animals bore the traces of luteal bodies formed in response to the initial exposure to oestrogen; other ovaries contained only large healthy or atretic follicles and spontaneous ovulation was apparently blocked. It is concluded that exposure of the hypothalamo-hypophysial system of the guinea-pig to an increased amount of oestrogen initially stimulates and then inhibits ovulatory gonadotrophin secretion. Tonic gonadotrophin secretion is unaffected.
REPTILIAN OVARIAN STEROIDOGENESIS AND THE INFLUENCE OF MAMMALIAN GONADOTROPHINS (FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE) IN VITRO
Authors: CHAN S. W. C. , CALLARD I. P.
Published: December 2008

The synthesis of steroids from [7α-3H]cholesterol, [7α-3H]pregnenolone and [7α-3H]progesterone by lizard and turtle ovarian tissues in vitro was studied. Progesterone, 17α-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, testosterone, oestrone and oestradiol were identified as products. In the turtle (Pseudemys), conversion of pregnenolone to progesterone was efficient, but transformation of progesterone to other steroids was relatively slow as indicated by the accumulation of progesterone over the incubation period. In Dipsosaurus, accumulation of radioactivity was greatest in testosterone, the quantities of which continued to increase at each sampling period. The rate of utilization of pregnenolone as a substrate was similar for the two species studied and the quantities of oestrone and oestradiol formed were lower in Pseudemys. The use of progesterone as precursor by Dipsosaurus ovarian tissue revealed a similar pattern of Δ4-steroid metabolism to that obtained with pregnenolone as precursor.

The effects of addition of purified follicle-stimulating hormone (FSH) and luteinizing hormone (LH) on the metabolism of [14C]cholesterol in vitro was studied using Pseudemys follicular tissue. The pattern of cholesterol metabolism was similar to that for pregnenolone in this species. The synthesis of pregnenolone, progesterone, dehydroepiandrosterone and androstenedione in vitro was significantly enhanced in the presence of LH. Follicle-stimulating hormone had no effect on steroid synthesis except for a decrease of androstenedione formation. The stimulatory effect of LH on steroidogenesis in vitro is discussed in relation to the literature suggesting that mammalian FSH, but not LH, stimulates all phases of reptilian ovarian function when injected in vivo.
A SURVEY OF THE STEROIDS IN COWS' MILK
Authors: DARLING J. A. B. , LAING A. H. , HARKNESS R. A.
Published: December 2008

A survey has been made of the steroids in cows' milk using a method for the group analysis of steroids. Serial studies during and after pregnancy showed changes in progesterone concentration consistent with known variations in plasma concentrations. More progesterone was obtained from samples taken at the later stages of milking and samples obtained in the evening generally contained more progesterone than morning samples. Steroids were concentrated in the cream.

Relatively constant levels of 5α-androstane-3,17-dione were found and it is suggested that this steroid is of adrenal origin. The predominance of 5α steroids in milk suggests that these are derived, at least in part, from metabolism in the mammary gland. The possible use of these findings in diagnosis of pregnancy and in studies of the hormonal control of lactogenesis is indicated.
CHROMATOGRAPHIC HETEROGENEITY OF IMMUNOREACTIVE LUTEINIZING HORMONE RELEASING HORMONE IN BLOOD FROM THE RABBIT, SHEEP AND RAT
Authors: JEFFCOATE S. L. , HOLLAND D. T.
Published: December 2008

Serum samples from rabbits, sheep and rats containing immunoreactive luteinizing hormone releasing hormone (LH-RH) have been extracted and fractionated by ion exchange chromatography on carboxymethylcellulose followed by radioimmunoassay of the fractions. Control experiments showed that the extraction and chromatographic procedures did not alter the mobility of synthetic LH-RH. Four immunoreactive components of circulating LH-RH in blood samples from various species at various times were identified on CM-cellulose columns. One of these had a mobility identical with that of synthetic LH-RH; of the others, two were eluted before and one after synthetic LH-RH. The nature, site of formation and possible significance of the extra components are discussed.
FRACTIONATION OF LIVER SOMATOMEDIN ACTIVITY BY ULTRAFILTRATION
Authors: DEHNEL JENNIFER M. , McCONAGHEY P. D. , FRANCIS M. J. O.
Published: December 2008

Plasma somatomedin is the intermediary through which growth hormone (GH) exerts its effects on the growing skeleton. Somatomedin activity may be produced in vitro by perfusion of the liver and kidneys of rats with Waymouth's medium containing GH. The relationship between the activity of plasma somatomedin and somatomedin of hepatic and renal origin has yet to be clarified. Somatomedin from plasma can be separated into active fractions of both high and low molecular weight. Similarly, ultrafiltration of medium containing somatomedin of hepatic origin indicates the existence of two active fractions, one of high molecular weight (greater than 50000) and one of low molecular weight (less than 1000). The latter can be attributed to the release of amino acids, such as serine and glutamine, by the perfused tissue. The high molecular weight fraction is believed to represent GH-dependent somatomedin. Fractions that inhibit production of cartilage matrix are present in liver perfusates as well as in plasma.

These results provide further evidence that the liver is a source of GH-dependent somatomedin in vivo. Furthermore, cartilage growth may be controlled not only by the GH-stimulated release of somatomedin by the liver, but also by its release of acid-labile somatomedin inhibitors.
EFFECTS OF HYPOPHYSECTOMY AND AGE ON THE INFUNDIBULAR NUCLEUS IN MAN
Authors: HOMMES O. R.
Published: December 2008

Cell density, length of the infundibular complex and size of the neuronal nuclei were measured in a group of patients surviving hypophysectomy after breast cancer, and in a group of patients without hypophysectomy.

Hypophysectomy decreased the length of the infundibular cell complex and the mean size of the neuronal nuclei and caused an increase in the difference between the cell density of the posterior and anterior part of the cell complex. In the hypophysectomized patients the mean nuclear size of neuronal nuclei and the length of the cell complex increased with survival time. These findings are interpreted as showing shrinkage of the infundibular nucleus after hypophysectomy. A return to normal values and possibly increased activity occur with survival times over 95 days.

The significance of the marked correlation between decrease of supraoptic cell population and the increase of mean nuclear size in the infundibular neurones of the hypophysectomized patients is discussed. In both groups the mean nuclear size of the infundibular neurones increased with age. The significance of this finding is discussed.
EFFECTS OF STEROID HORMONES ON GONADOTROPHIN SECRETION IN FEMALE RATS AFTER OVARIECTOMY DURING THE OESTROUS CYCLE
Authors: TAPPER C. M. , GREIG FENELLA , BROWN-GRANT K.
Published: December 2008

After ovariectomy at dioestrus, a dose of 2·5 μg oestradiol or oestradiol benzoate restored uterine weights and the vaginal smear pattern to normal but did not reproduce the normal ovulatory surge of luteinizing hormone secretion at pro-oestrus. Progesterone in addition to oestrogen was more effective than oestrogen alone in stimulating luteinizing hormone secretion but responses at pro-oestrus or at oestrus were not normal. Deviations from the normal pattern of changes in plasma oestradiol concentration do not provide an adequate explanation for the failure of steroid replacement in these circumstances. Inhibition of the priming effect of exogenous oestrogen by adrenal progesterone released by the stress of operation may provide an explanation.
OVARIAN DEVELOPMENT IN THE FEMALE RING DOVE IN RESPONSE TO STIMULATION BY INTACT AND CASTRATED MALE RING DOVES
Authors: CHENG MEI-FANG
Published: December 2008

Six ovarian stages were identified in terms of egglaying latency in female ring doves (Streptopelia risoria); each stage is specified by a range of follicle sizes, characteristic follicle colour, vascularity and appearance of the oviduct. Relationships between these ovarian stages and cytological changes, levels of ovarian hormones and behavioural changes were examined. In another experiment female doves at different ovarian stages were paired with intact or castrated male birds to evaluate the effects of different levels of courtship activity on ovulation and egg-laying. Castrated male birds were effective in stimulating ovarian development culminating in egg-laying in females of advanced ovarian stage, but ineffective in female birds at earlier ovarian stages. In view of this, the decline of male courtship activity seen in normal breeding may have an important function in the reproductive biology of this species.
INFLUENCE OF ADRENAL STEROIDS ON LIVER ENZYMES OF NEONATALLY CASTRATED RATS
Authors: GUSTAFSSON JAN-ÅKE , STENBERG ÅKE
Published: December 2008

The metabolism of [4-14C]4-androstene-3,17-dione and [4-14C]5α-androstane-3α,17β-diol were studied in the microsomal fraction and the metabolism of [4-14C]4-androstene-3,17-dione was studied in the 105000 g supernatant fraction of liver from adult male rats castrated at birth or at 14 days of age. Some of these rats were adrenalectomized 6 weeks after castration and given dexamethasone substitution for 14 consecutive days and some were not adrenalectomized and were treated with adrenocorticotrophin for 14 days. Untreated, castrated control rats were also investigated. Adrenalectomy combined with dexamethasone substitution was found to abolish the masculine, imprinted character of the activities of 16α-hydroxylase, 17α- and 17β-hydroxysteroid reductases and 5β-reductase active on 4-androstene-3,17-dione and 2α- and 2β-hydroxylases active on 5α-androstane-3α,17β-diol in liver from male rats castrated at 14 days of age. The type of androgenic regulation characterizing these enzymes was called 'less stable' imprinting. In contrast to these findings, the activities of 5α-reductase and 3β-hydroxysteroid reductase retained their masculine character in male rats castrated 14 days after birth even after adrenalectomy combined with glucocorticoid substitution. The type of programming regulating these enzyme activities was called 'more stable' imprinting.

'Less stable' imprinting could be explained by the increased androgen responsiveness of the neonatally androgenized liver which thus responds more promptly to the enzyme-inducing or suppressing effects of adrenal androgens. Adrenalectomy combined with dexamethasone substitution results in elimination of these effectors and consequently loss of the masculine character of the enzyme activities regulated by 'less stable' imprinting. The activity of 5β-reductase, however, seems to be regulated by unknown central factors. 'More stable' imprinting may be explained by a specific, autonomous, irreversible enzyme induction in liver independent of postpubertal hormonal stimuli.

Corticotrophin treatment generally led to similar but less significant effects upon the hepatic enzyme activities than adrenalectomy combined with dexamethasone substitution. It is speculated that these effects may be attributable to increased glucocorticoid levels in blood possibly through secondary effects on central control mechanism(s) regulating hepatic enzyme activities.
ABSORPTION AND SECRETION IN THE CAUDA EPIDIDYMIDIS OF THE RABBIT AND THE EFFECTS OF DEGENERATING SPERMATOZOA ON EPIDIDYMAL PLASMA AFTER CASTRATION
Authors: JONES ROY
Published: December 2008

The origins of the constituents of epididymal plasma from the cauda epididymidis of the rabbit have been investigated. Results show that the epididymis actively absorbs Na+ and Cl− ions and actively secretes glycerylphosphorylcholine, protein, alkaline phosphatase, acid phosphatase, β-N-acetylglucosaminidase, α-mannosidase and acid deoxyribonuclease. Degenerating spermatozoa contribute K+ ions and material giving a positive reaction with diphenylamine reagent. It is suggested that in a normal animal, spermatozoa are suspended in a 'degradative milieu' and that this is involved in the disappearance of spermatozoa after castration.
INTERRELATIONSHIPS OF PITUITARY AND PLASMA CORTICOTROPHIN AND PLASMA CORTICOSTERONE IN ADRENALECTOMIZED AND STRESSED, ADRENALECTOMIZED RATS
Authors: BUCKINGHAM JULIA C. , HODGES J. R.
Published: December 2008

Changes in pituitary and plasma corticotrophin (ACTH), estimated by redox bioassay, were correlated with changes in plasma corticosterone in adrenalectomized rats, with and without corticosterone treatment, before and after exposure to stress. After adrenalectomy, the plasma ACTH concentration was persistently increased. The pituitary ACTH content declined and then increased markedly. These changes were prevented by physiological doses of corticosteroids. Stress caused only a small rise in the plasma ACTH concentration in intact and sham-operated rats but a marked increase in adrenalectomized animals. This exaggerated response was reduced to normal by physiological doses of corticosterone. Prolonged treatment with higher doses of corticosterone was necessary to abolish completely the adrenocorticotrophic response to stress. However, one injection of the steroid, in a dose sufficient to raise the plasma corticosterone concentration to a similar level, did not impair the stress-induced release of ACTH. The results suggest that the synthesis and the basal release of ACTH are directly controlled by the concentration of corticosteroid in the blood, but the corticosteroids exert only a delayed effect in modulating the stress-induced release of the hormone.
PROGESTERONE AND ANDROGEN RECEPTORS IN NON-FLAGELLATE GERM CELLS OF THE RAT TESTIS
Authors: GALENA H. J. , PILLAI A. K. , TERNER C.
Published: December 2008

In continuation of a previously reported study which showed that isolated non-flagellate germ cells of the rat testis metabolize progesterone to androgens, a search was made for the presence in these cells of specific progesterone and androgen receptors. Intact germ cells and their cytosol and nuclear fractions were incubated with 3H-labelled steroids; established analytical techniques were used to distinguish specific from non-specific binding. The steroid-protein complexes of progesterone, testosterone and dihydrotestosterone were partially purified by Sephadex column chromatography, acrylamide gel electrophoresis and sucrose density gradient analysis. The association constants of the three protein–steroid complexes were about 2 × 109 l/mol. The non-flagellate germ cells of the testis were found to have a higher binding capacity for progesterone than for testosterone and dihydrotestosterone. Epididymal spermatozoa did not bind progesterone specifically, but bound dihydrotestosterone to about the same extent as nuclei of non-flagellate cells. In extracts of seminal vesicles and prostate glands androgen binding was dominant, with negligible binding of progesterone. Synthetic progestogens (anti-androgens) competed effectively for the progesterone binding sites of the non-flagellate cells. In view of the finding that non-flagellate germ cells bind progesterone specifically and convert it to androgens, it is suggested that the metabolism of progesterone within the seminiferous epithelium of the testis may serve the purpose of maintaining an intratubular level of androgen for the support of spermatogenesis, independent of the extratubular secretion of androgen by the Leydig cells.
INFLUENCE OF OVINE PROLACTIN ON TRANSPORT OF FLUID AND SODIUM CHLORIDE BY THE MAMMALIAN INTESTINE AND GALL BLADDER
Authors: MAINOYA J. R. , BERN H. A. , REGAN J. W.
Published: December 2008

Mucosal fluid, sodium and chloride transfer were measured in everted sacs of rat, guinea-pig and hamster jejunum, and in rat ileum and colon, and in guinea-pig gall bladder. After treatment of the animal with ovine prolactin, a highly significant enhancement of fluid and NaCl absorption was observed in rat, hamster and guinea-pig jejunum. Prolactin treatment caused a significant increase in fluid and NaCl transfer in rat ileum, but not in guinea-pig ileum or rat colon. Prolactin administration had no consistent effect on fluid and NaCl absorption by the guinea-pig gall bladder. The several regions of the mammalian gut appear to differ in their responsiveness to prolactin.
DISTRIBUTION OF THE OESTROGEN-INDUCED PROTEIN AND OF TOTAL PROTEIN BETWEEN ENDOMETRIAL AND MYOMETRIAL FRACTIONS OF THE IMMATURE AND MATURE RAT UTERUS
Authors: KATZENELLENBOGEN BENITA S. , LEAKE R. E.
Published: December 2008

Using two methods for preparation of endometrial and myometrial tissue fractions – a new method based on mincing and gentle maceration of the immature rat uterus, or separation by dissection of endometrium and myometrium from the mature uterus – both controlled histologically, we have analysed the distribution of the oestrogen-induced protein (IP), and total protein and DNA in these endometrial and myometrial fractions. Studies with both immature and mature oestrogen-stimulated uteri indicate that IP is synthesized in both the endometrial and myometrial tissues. In the immature uterus, there was a marked enrichment of IP in the endometrial fraction. When macerated for 20 or 50 s, 60–70% of the total IP, 5% of the total DNA, 9% of the total protein, and 24–30% of the total soluble protein were found in the endometrium. This enrichment is shown to be due most likely to preferential synthesis of IP in the endometrium. In contrast, in the mature uterus, there was no significant enrichment of IP in the endometrium. Since IP synthesis is associated with the action of oestrogen on both endometrium and myometrium, and the ultimate physiological effects of oestrogen on the two tissues seem to be different, the divergence of the action of oestrogen in these tissues may occur at some point after IP synthesis.
INFLUENCE OF AGE AND DURATION OF TREATMENT ON THE EFFECTS OF TESTOSTERONE ON SERUM AND PITUITARY FOLLICLE-STIMULATING HORMONE LEVELS IN MALE RATS
Authors: SHARPE R. M. , SHAHMANESH M.
Published: December 2008

Male rats aged 30, 60 or 125 days were injected once every 5 days with 5 mg of a long-acting testosterone preparation, or its vehicle, for periods of 5–40 days. Pituitary and serum follicle-stimulating hormone (FSH) levels were determined by bioassay and radioimmunoassay respectively. Treatment with testosterone produced a consistent pattern of change in pituitary FSH levels (compared with control animals) over a period of 35 days: an initial increase in relative FSH levels was followed by a sharp drop after which there was a further increase in content. However, the magnitude and rate of these changes varied according to the age of the animals involved. These changes in pituitary FSH levels are considered to reflect mainly changes in synthesis, as secretion of FSH was apparently reduced at all ages in testosterone-treated animals. The age-dependent changes in FSH synthesis in testosterone-treated animals may reflect a decrease in sensitivity to testosterone feedback with increase in age. Moreover, in untreated male rats the decrease in FSH secretion after 35 days of age and the apparent reduction in FSH synthesis after 76 days of age could be accounted for by changes in serum testosterone levels.
RESTORATION BY OESTRADIOL BENZOATE OF A NEURAL AND HORMONAL RHYTHM IN THE OVARIECTOMIZED RAT
Authors: BURNET F. R. , MACKINNON P. C. B.
Published: December 2008

The rate of [35S]methionine incorporation into protein in discrete cerebral areas was measured before and after the administration of oestradiol benzoate (OB) to chronically ovariectomized rats. The circadian rhythm of incorporation which is normally seen in the intact cyclic female rat was deleted by ovariectomy. A daily rhythm of incorporation reappeared, however, in all the brain areas studied 30 h after a single injection of OB (20 μg), and was still present 12 days later.

The release of luteinizing hormone (LH) after administration of 20 μg OB was measured in chronically ovariectomized animals and was found to be biphasic. High levels of LH after ovariectomy were initially reduced by negative feedback, but this phase was followed 52 h later by a facilitation of LH release between 15.00 and 18.00 h. The facilitation of LH release at this time of day was still detectable 12 days after the initial injection.

The evidence for a functional link between the rhythm of neural activity which is reflected by [35S]methionine incorporation, and the ability to 'time' the facilitation of LH release is discussed.
EFFECTS OF HYPOTHALAMIC EXTRACTS, NEUROTRANSMITTERS AND SYNTHETIC HYPOTHALAMIC RELEASING HORMONES ON ADENYLYL CYCLASE ACTIVITY IN THE LOBES OF THE PITUITARY OF THE DOGFISH (SCYLIORHINUS CANICULA L.)
Authors: DEERY D. J. , JONES A. C.
Published: December 2008

Neutralized acid extracts of the median eminence of the dogfish hypothalamus were found to cause a dose-related activation of adenylyl cyclase in all lobes of the dogfish pituitary. Equal concentrations of extracts of extrahypothalamic areas of the dogfish brain did not activate the enzyme.

The putative neurotransmitters melatonin, serotonin, adrenaline, noradrenaline, dopamine and acetylcholine were without effect, as were the prostaglandins E1 and E2.

The effects of synthetic mammalian hypothalamic hormones were also studied. Both thyrotrophin releasing hormone and gonadotrophin releasing hormone activated the ventral lobe enzyme, but had no effect on the adenylyl cyclase of the other three lobes. The tripeptide, Pro-Leu-Gly-NH2, a possible melanocyte-stimulating hormone release-inhibiting factor had no effect on the enzyme of the neurointermediate lobe.

It is suggested that all four lobes of the dogfish pituitary may be under hypothalamic control and that this control is likely to be mediated by peptide hormones, as in mammals.
PLASMA LEVELS OF LUTEINIZING HORMONE IN GONADECTOMIZED JAPANESE QUAIL EXPOSED TO SHORT OR TO LONG DAYLENGTHS
Authors: GIBSON W. R. , FOLLETT B. K. , GLEDHILL BARBARA
Published: December 2008

Plasma levels of luteinizing hormone (LH) were measured by radioimmunoassay in gonadectomized male and female Japanese quail, exposed either to 8 h light: 16 h darkness per day (8L:16D; short days) or to 20L:4D (long days). In both sexes, exposure to long days increased LH levels and in the gonadectomized quail LH continued to rise over several weeks. Eventually the castrated quail had levels about five times higher than the control birds and the ovariectomized quail had levels about 14 times higher than their controls.

Quail kept on short days had low LH levels while birds kept on long days and returned to short days resumed low levels after a delay of some days. Since very high levels of LH occurred in gonadectomized quail only when they were on long days, we conclude that the photoperiodic regulation of LH secretion does not operate solely by adjusting sensitivity to gonadal feedback, but works in a more direct manner.

Ovariectomized females whether on long days (high LH) or short days (low LH) grew masculine plumage and castrated males retained male plumage. This confirms that the ovary is responsible for sexual dimorphism of plumage and shows that the action of the ovary is not mediated by LH (through feedback).

The remaining rudimentary (right) gonad in ovariectomized females did not undergo visible hypertrophy and did not secrete enough hormone to stimulate the cloacal gland or oviduct.
EFFECT OF CALCIUM DEPRIVATION ON PARATHYROID HORMONE-MEDIATED BONE AND KIDNEY CONTRIBUTIONS TO THE MAINTENANCE OF PLASMA CALCIUM IN RATS
Authors: KALU D. N. , HADJI-GEORGOPOULOS A. , FOSTER G. V.
Published: December 2008

This study was designed to investigate the roles of bone and kidney in the acute regulation of plasma calcium by parathyroid hormone (PTH) during prolonged calcium deprivation. The effect of PTH was assessed by gland ablation. Animals were thyroparathyroidectomized or sham-operated and their urine was collected for 3 h. Subsequently they were anaesthetized and bled from the abdominal aorta. In rats fed on a low calcium diet, urinary hydroxyproline excretion was enhanced and, unlike animals fed on a normal diet, decreased 3 h after thyroparathyroidectomy (TPTX). In addition TPTX decreased plasma calcium by 0·45 mg/100 ml in normal rats compared with 1·94 mg/100 ml in animals fed on a calcium-deficient diet. Urinary calcium increased by 161 and 12 μg and accounted for 82 and 1·4% of the fall in plasma calcium in normal and calcium-deprived animals respectively. The corresponding contributions of bone were 18 and 98·6%. These findings support the view that with prolonged calcium deprivation in adult rats, the relative contributions of bone and kidney to the acute regulation of the plasma calcium level by PTH are reversed. As a result, bone rather than kidney becomes the more important organ. At the same time non-PTH-mediated kidney reabsorption of calcium is increased.
EFFECT OF SEROTONIN AND PROGESTERONE ON INDUCED OVULATION IN IMMATURE RATS
Authors: WILSON CATHERINE A. , HORTH C. E. , McNEILLY A. , McDONALD P. G.
Published: December 2008

Serotonin (50 and 100 mg/kg), given subcutaneously, inhibited induced ovulation in immature rats treated with pregnant mare serum gonadotrophin (PMSG). A single injection was effective if given 52–55 h after the PMSG, i.e. in the 3 h period after the critical period before ovulation. The injection of serotonin inhibited the release of luteinizing hormone (LH) from the pituitary since the pituitary levels were higher than in the control animals and there was complete inhibition of the plasma LH surge. The antiovulatory effect was reversed by administration of progesterone and endogenous plasma progesterone levels were reduced in the late evening after serotonin treatment. The site of action of serotonin appeared to be peripheral since it inhibited induced ovulation in hypophysectomized rats but was without effect in intact rats treated intraventricularly. It is suggested that progesterone is essential for the occurrence of induced ovulation and serotonin inhibits either its secretion at the ovarian level or its passage away from the ovary.
THYROTROPHIN CONCENTRATIONS IN THE PLASMA OF CATTLE, SHEEP AND FOETAL LAMBS AS MEASURED BY RADIOIMMUNOASSAY
Authors: HOPKINS P. S. , WALLACE A. L. C. , THORBURN G. D.
Published: December 2008

A radioimmunoassay technique for measuring the thyrotrophin (TSH) concentration of sheep and cattle plasma is described. The sensitivity of the assay allowed the measurement of 1–50 ng TSH/ml unextracted plasma. Cross-reaction with ovine luteinizing hormone, prolactin and growth hormone was very low. The average recovery of added TSH was 103 ± 4·1 (s.e.m.)% and the between-assay coefficient of variation was 13·8%.

The normal plasma TSH levels of sheep and cattle were approximately 2·5 ng/ml (5 mu. bovine TSH/100 ml). Foetal sheep had plasma TSH concentrations of approximately 3·2 ng/ml during the last 20 days of gestation. Levels of TSH in the circulation decreased abruptly after hypophysectomy of the foetal lamb and a decline in the plasma thyroxine (T4) concentrations was also apparent within 24 h of the operation. However, thyroidectomy of adult and foetal sheep did not increase plasma TSH concentrations until almost all the T4 had been cleared from the circulation.

The injection of T4 into thyroidectomized sheep rapidly reduced plasma TSH concentrations to normal values. However, the continued injection of T4 did not further reduce TSH concentration. The injection of T4 or triiodothyronine into normal sheep was also without effect on plasma TSH concentrations.
HYPOPHYSECTOMY OF THE TAMMAR WALLABY, MACROPUS EUGENII: SURGICAL APPROACH AND GENERAL EFFECTS
Authors: HEARN J. P.
Published: December 2008

A technique of hypophysectomy and regimes of pre- and post-operative care were developed for the tammar wallaby, Macropus eugenii, to a stage when animals can survive the operation with little apparent stress.

Thyroid and adrenal gland weights declined after hypophysectomy, especially within the first 20–30 days. Changes in the adrenal cortex after hypophysectomy suggested that this region may have a zonal organization different from that in eutherian mammals. The reproductive tracts of males and females lost weight rapidly after hypophysectomy.

Eleven plasma parameters were studied for the effects of hypophysectomy. There was a reduction in sodium and chloride and a tendency to higher potassium levels, reflecting inadequate adrenal cortical function. Calcium and total protein values remained unaffected, but inorganic phosphate, glucose and cholesterol were depleted, and a less significant depletion in blood urea, nitrogen and uric acid was evident.
GEL FILTRATION OF HUMAN URINARY IMMUNOREACTIVE LUTEINIZING HORMONE
Authors: YOUNG J. L. , HARSOULIS P. , KUKU S. F. , FRASER T. R.
Published: December 2008

In human urinary concentrates and also in a urinary gonadotrophin standard (2nd IRP-HMG), gel-filtration analysis revealed three main peaks of immunoassayable luteinizing hormone (LH). A similar analysis of LH extracted from human pituitaries showed most of the activity in a peak of larger molecular weight, and only minor fractions in the positions of the urinary peaks. In an extract of normal human serum, analysis showed only one similar peak of large molecular weight, which also emerged before the urinary peaks.

During an i.v. infusion of pituitary LH into normal men, the urinary LH activity increased but was still found only in the same three peaks on gel filtration, and all were of a molecular weight smaller than that of the infused material; but a higher proportion of the urinary LH was found in the earliest of these peaks compared with that found before infusion. Conversely, 20–35 h after the i.v. infusion, there was a slightly higher proportion of LH activity in the third peak of smallest molecular weight.

These findings suggest that the urinary immunoassayable LH, which is found in three peaks of different molecular weights, is derived from the pituitary or serum LH of higher molecular weight. The changes in the proportions of larger or smaller molecular weight fractions in the urine during and after LH infusion suggest that the earliest peak may be disaggregated serum LH, while the last or smallest molecular weight peak may comprise metabolites of LH.
EFFECTS OF OVARIAN STEROID HORMONES ON ESTERASES IN THE RAT ENDOMETRIUM
Authors: BOSHIER D. P. , KATZ JUNE M.
Published: December 2008

A technique in which uterine luminal epithelium is separated from the remainder of the endometrium by rapidly vibrating everted uterine cornua in a 3·5 mm solution of EDTA has been developed. Examination of the hormonal sensitivities and physiological roles of the tissue components of the endometrium is thus facilitated.

Biochemical and histochemical studies of epithelial, stromal and endometrial esterases have shown that the rate of hydrolysis of α-naphthyl acetate is significantly higher in epithelial and endometrial tissue extracts during pro-oestrus than at any other stage of the oestrous cycle. In ovariectomized animals, oestradiol-17β caused a 60% increase in the rate of esterase activity over that of control animals, whereas medroxyprogesterone acetate had no effect. These findings suggest that the variations in the levels of neutral lipids in the uterine luminal epithelium of non-pregnant mature female rats result from the periodic stimulation of the epithelial esterases by the cyclically increased levels of plasma oestrogens.
THE EFFECT OF DAYLENGTH AND LEVEL OF FEEDING ON SERUM PROLACTIN IN GROWING LAMBS
Authors: FORBES J. M. , DRIVER P. M. , EL SHAHAT A. A. , BOAZ T. G. , SCANES C. G.
Published: December 2008

Twenty-four castrated male lambs initially maintained on a photoperiod of 12 h light: 12 h dark were allocated to a factorial experiment with two daylengths 8 h L: 16 h D or 16 h L: 8 h D) and two levels of feeding (restricted or ad libitum). Blood samples were taken every 4 h for 24 h during the introductory period and after 24, 51 and 79 days of treatment.

There were highly significant positive effects of daylength and level of feeding on serum prolactin: mean concentrations increased from a mean of 38 ± 1 ng/ml during the introductory period until at day 79 they were: 8L:16D (restricted diet), 81 ng/ml; (food ad libitum), 167 ng/ml; 16L:8D (restricted diet), 262 ng/ml; (food ad libitum), 262 ng/ml (s.e. of treatment mean ± 4). Long daylength and feeding ad libitum also significantly increased growth rate.
HORMONAL REGULATION OF LOBULO-ALVEOLAR GROWTH, FUNCTIONAL DIFFERENTIATION AND REGRESSION OF WHOLE MOUSE MAMMARY GLAND IN ORGAN CULTURE
Authors: WOOD BONNIE G. , WASHBURN LINDA L. , MUKHERJEE A. S. , BANERJEE M. R.
Published: December 2008

The entire second thoracic mammary glands of 4-week-old BALB/c female mice primed with oestradiol plus progesterone were cultivated in organ culture medium containing the 'growth-promoting' hormone combinations: insulin, prolactin, growth hormone, oestradiol, progesterone and aldosterone or insulin, prolactin and aldosterone. Full lobulo-alveolar development was induced after 5–6 days of incubation and could be maintained for 15–16 days in organ culture in medium containing either hormone combination. After the initial 5–6 days in the 'growth-promoting' medium, subsequent cultivation of the glands in a medium with the 'lactogenic hormones', insulin, prolactin plus cortisol, led to accumulation of 'milk-like' secretory material in the ductal and alveolar lumina. Incubation of the lobulo-alveolar gland in medium with insulin alone for 7–9 days resulted in complete regression of the alveoli leaving only a ductal parenchyma. Incubation in insulin, prolactin, growth hormone or insulin plus the steroid hormones for 7–9 days led to considerable alveolar degeneration without a complete regression. The results indicate that both pituitary and steroid hormones are essential for development and maintenance of mammary alveoli; insulin can only sustain the basal ductal structure.
RATE OF THYROXINE SECRETION BY MALE AND LAYING JAPANESE QUAIL: IDENTIFICATION OF THE RADIOACTIVE THYROXINE DEGRADATION COMPONENT OF THE MULTIPHASIC 131I CURVE
Authors: ROBINSON G. A. , TAM K. H.
Published: December 2008

Counting of radioactivity in Japanese quail in vivo showed a rapid loss of 131I from the body 12–24 h after the i.v. injection of [131I]thyroxine (T4), followed by a period of slow decrease in counting rates to 96 h. From comparison of these [131I]T4 curves with curves for 131iodide-injected birds and from counts on serum and other tissues in vitro it was concluded that, for Japanese quail, the T4 secretion rate should be calculated using serum samples taken during the first 12 h. Using this time period, the parameters measured were: T4 distribution space, laying hens 45·7 and mature cocks 26·3 ml/100 g body weight; fractional degradation rate for T4, hens 5·73 and cocks 3·12/day; serum T4 concentration (Tetrasorb125 method), hens 1·20 ± 0.07 and cocks 1·34 ± 0.05 (s.e.m.)μg/100 ml (n= 16); T4 secretion rate, hens 3·14 and cocks 1·10 μg/100 g/day.
STEROID ENTRY INTO RETE TESTIS FLUID AND THE BLOOD-TESTIS BARRIER
Authors: COOPER T. G. , WAITES G. M. H.
Published: December 2008

Evidence that steroids enter rete testis fluid (RTF) from the blood at varying rates was obtained during i.v. infusions into rats. Testosterone and dehydroepiandrosterone were readily transferred into the fluid, whereas cholesterol was excluded. Between these extremes, the appearance of radioactivity in the RTF suggested the following order of entry rate: progesterone > pregnenolone > 5α-reduced androgens > oestrogens > corticosteroids.

Preliminary identification of metabolites in RTF and blood suggested that testosterone and dehydroepiandrosterone were transferred largely unchanged. Androstenedione and progesterone, however, were largely metabolized during transfer into the RTF, the former being transformed to testosterone.

The results are used to discuss the nature of the blood-testis barrier to steroids and the source of androgens in the RTF.
METABOLIC EFFECTS OF TESTOSTERONE IN THE CHEQUERED WATER-SNAKE, NATRIX PISCATOR
Authors: THAPLIYAL J. P. , GUPTA S. C. , GARG R. K.
Published: December 2008

In the water-snake, Natrix piscator, the following are depressed by orchidectomy and restored to normal by testosterone treatment: glucose, free and esterified fatty acids and triglycerides in plasma, hepatic triglycerides, and total esterified fatty acids.

The increase in hepatic free fatty acids and muscle glycogen was also reduced to the level found in intact snakes. Moreover, although castration had no effect, testosterone caused a significant increase in liver weight and plasma protein, and a significant decrease in free plasma cholesterol. Except for an increase in triglyceride content by high doses of the hormone, neither castration nor the administration of 5 mg testosterone had any significant effect on the free fatty acid and triglyceride content of the adipose tissue of the snakes.
A COMPARISON OF CHANGES IN THE PERIPHERAL PLASMA CONCENTRATIONS OF LUTEINIZING HORMONE AND FOLLICLESTIMULATING HORMONE IN THE RAT
Authors: BROWN-GRANT K. , GREIG FENELLA
Published: December 2008

Plasma FSH concentrations in rats have been determined by radioimmunoassay under a variety of experimental conditions to see whether any evidence could be obtained of an acute divergence in LH and FSH secretion rates which would support the idea of separate, specific hypothalamic releasing factors for these two hormones.

During the normal ovarian cycle and after the administration of progesterone to female rats on the morning of the day of pro-oestrus increased secretion of both LH and FSH began simultaneously but FSH concentrations were later maintained or increased slightly while LH concentrations were falling. During early pregnancy FSH concentrations were higher than at the corresponding stage of the cycle at a time when LH concentrations had been shown to be lower. Progesterone injected at the dioestrous stage of the cycle reduced both LH and FSH concentrations though the effect on LH was more marked. After ovariectomy at any stage of the oestrous cycle or on day 4 of pregnancy there was a rapid and significant increase in plasma FSH concentration which was quite different from the delayed increase in LH concentration observed in these animals. In contrast, the early increase in FSH concentration in male rats after castration was less than the increase in LH concentration. The final FSH concentration in castrated males was only about four times the basal level in contrast to the 10- to 15-fold increase in LH in males and both LH and FSH in females. Anovulatory adult females that had received 1·25 mg of testosterone propionate on day 4 of postnatal life showed the rapid and sustained increase in plasma FSH after ovariectomy that was seen in normal females.

None of these results strongly support the idea that separate and specific hypothalamic releasing factors for LH or FSH are secreted in the rat although the differences in the early response to gonadectomy could be explained on this basis.
STEROIDOGENESIS IN CEREBRAL METASTATIC CHORIONEPITHELIOMA TISSUE IN VITRO
Authors: MAEYAMA M. , IFUKU M. , NAKAHARA K.
Published: December 2008

Homogenates of cerebral metastatic chorionepithelioma tissue were incubated with labelled dehydroepiandrosterone, pregnenolone or 20α-hydroxypregn-4-en-3-one. The metabolites of dehydroepiandrosterone which were isolated and identified were androstenedione, testosterone, oestrone and oestradiol; no oestriol was detected. The only metabolite of pregnenolone and 20α-hydroxypregn-4-en-3-one isolated and identified was progesterone. No conversion of C-21 to C-19 steroids occurred in the metastatic chorionepithelioma tissue.
GONADOTROPHIC STIMULATION OF OESTROGEN SYNTHESIS BY CULTURED IMMATURE MOUSE OVARIES
Authors: RYLE MARGARET , COURT JENNIFER , SMITH TERESA , MORRIS R.
Published: December 2008

The amount of oestrogen produced by immature mouse ovaries cultured with purified gonadotrophins was measured by means of a radioimmunoassay. Small quantities were released in response to FSH or LH alone, but when both were provided production was greatly enhanced after an initial lag phase of 2–3 days. The lowest concentrations required to produce this synergistic effect were between 0·02 and 0·13 i.u. FSH/ml and between 0·01 and 0·1 i.u. LH/ml. After prolonged exposure to 0·4 i.u. FSH/ml plus 1·0 i.u. LH/ml, oestrogen output continued to rise until, on the ninth day of culture, it reached 2·6–7·3 ng/ ovary/day. Pre-treatment with 0·4 i.u. FSH/ml for 3 days enhanced the subsequent response to combined gonadotrophins but the simultaneous presence of FSH and LH was essential for inducing the delayed synergistic effect. Although both gonadotrophins also stimulated follicle growth there was no evidence suggesting any simple correlation between that response and oestrogen synthesis. Maximal oestrogen production coincided with very low follicular mitotic activity.
HYSTERECTOMY OF THE NEWBORN GUINEA-PIG, SUBSEQUENT EFFECTS ON THE OESTROUS CYCLE AND LIFE SPAN OF THE CORPORA LUTEA
Authors: BUÑO W. , CARLEVARO E. , RIBONI L. , D'ALBORA H. , DE LOS REYES L. , ZIPITRIA D. , DOMÍNGUEZ R.
Published: December 2008

Longer oestrous cycles result from neonatal hysterectomy than from hysterectomy in adult life. Section and cauterization of the utero-vaginal union also prolonged the vaginal closure period up to an average of 55 days. The destruction of the mesometrium did not lengthen the oestrous cycle.

Uterine autografts in hysterectomized newborn guinea-pigs did not prevent the long cycles.
SERUM LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, PROLACTIN AND PROGESTERONE CONCENTRATIONS AND FOLLICULAR DEVELOPMENT IN THE PSEUDOPREGNANT RAT AFTER UNILATERAL OVARIECTOMY
Authors: DE GREEF W. J. , DULLAART J. , ZEILMAKER G. H.
Published: December 2008

Serum LH, FSH, prolactin and progesterone concentrations and follicular size were measured in rats during pseudopregnancy after unilateral ovariectomy (ULO) on day 1. This operation did not affect the duration of pseudopregnancy. Following pseudopregnancy compensatory ovulation occurred.

After ULO progesterone concentrations remained low as compared with control values but the progesterone secretion per ovary was increased slightly. After ULO, LH concentrations were significantly increased on days 3 and 4 of pseudopregnancy. FSH concentrations were increased 5 h after the operation and again on days 4–7 of pseudopregnancy when compared with sham-operated control animals. During pseudopregnancy prolactin secretion increased each night. Increased prolactin levels were observed 18 and 36 h after ULO. The number of medium-sized follicles had increased 24 h after ULO.

From the present study it is concluded that progesterone secretion by the corpora lutea can be increased to a limited degree by the increased release of gonadotrophins. Furthermore, it is concluded that a rapid increase in FSH concentrations after ULO is responsible for the initiation of the compensatory follicular growth.
REGION-SPECIFIC IMMUNOASSAYS FOR PARATHYROID HORMONE
Authors: BARLING P. M. , HENDY G. N. , EVANS M. C. , O'RIORDAN J. L. H.
Published: December 2008

Immunoassays specific for limited regions of bovine parathyroid hormone were developed in four ways.

With the heterogeneous antisera produced by immunizing with intact bovine parathyroid hormone (BPTH 1–84), the specificity of radioimmunoassays could be enhanced by presaturating either with an amino-terminal (BPTH 1–34) or carboxy-terminal (BPTH 53–84) fragment. Then, the antibodies which had not been neutralized reacted exclusively with the opposite end of the molecule, even using [125I]BPTH 1–84 as tracer. With some antisera, the appropriate fragment and intact hormone reacted identically. However, with other antisera, the fragment reacted less well than the intact hormone, possibly because these antisera contain antibodies reacting with the middle of the molecule.

Using the labelled fragment ([125I]BPTH 1–34) as tracer, with heterogeneous antisera, radioimmunoassays specific for the amino-terminal region were obtained. With one antiserum, BPTH 1–34 reacted identically with the intact hormone, but with another antiserum, the fragment was more reactive than the intact molecule.

A region-specific radioimmunoassay was also developed using antibodies produced by immunization with a fragment of the hormone. An antiserum raised against BPTH 1–34 had high affinity for the amino-terminal fragment, but reacted less well with the intact hormone.

Immunoradiometric assays, specific for the amino- or carboxy-terminal regions, were developed by using immunoadsorbents consisting of a fragment (either BPTH 1–34 or BPTH 53–84) coupled to cellulose. These were used to fractionate 125I-labelled antibodies. With some of these selected antibodies, the appropriate fragment was of lower reactivity than the intact hormone. This may have been due to the presence of an incomplete antigenic site on the fragment, or to conformational differences between the fragment and the corresponding region of the intact hormone. With other selected antibodies the fragment and the intact molecule reacted identically.

Careful selection of antisera and of technique is necessary to obtain an assay in which a fragment and the intact hormone behave identically.
CHANGES IN THE CONCENTRATION OF CALCITONIN IN THE PLASMA OF CHICK EMBRYOS DURING INCUBATION
Authors: TAYLOR T. G. , BALDERSTONE OLWEN , LEWIS PAMELA E.
Published: December 2008

Calcitonin (CT) was assayed in the plasma of chick embryos at eight stages of development from day 17 of incubation to day 1 after hatching by a rat bioassay. The concentration of CT rose steadily from 1060 mu./l on day 17 to 4700 mu./l at the stage when pulmonary respiration was initiated on day 20. Nine hours later, when the embryos 'pipped' the shells, the concentration of the hormone more than doubled to reach a peak of 11000 mu./l. At hatching the level had fallen to 1400 mu./l and 24 h later it was undetectable (< 500 mu./l). The physiological significance of these changes is discussed in relation to the development of the embryo.