bluuebunny/crossref_metadata_2025_split huggingface dataset:
A SURVEY OF THE STEROIDS IN COWS' MILK
Authors: DARLING J. A. B. , LAING A. H. , HARKNESS R. A. 
Published: December 2008

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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

SUMMARY
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.