bluuebunny/crossref_metadata_2025_split huggingface dataset:
RELEASING FACTOR AND HORMONAL CHANGES IN THE HYPOTHALAMIC-PITUITARY-GONADOTROPHIN AND -ADRENOCORTICOTROPHIN SYSTEMS BEFORE AND AFTER BIRTH AND PUBERTY IN MALE, FEMALE AND ANDROGENIZED FEMALE RATS
Authors: CHIAPPA SHARON A. , FINK G. 
Published: December 2008

SUMMARY
The hypothalamic content of LH releasing factor (RF), pituitary ACTH and pituitary and plasma LH and FSH were measured by radioimmunoassay from foetal Day 15 to postnatal Day 65. Bioassayable corticotrophin releasing activity was also measured during the postnatal period. Hypothalamic LH-RF was detectable as early as foetal Day 15, increasing gradually until postnatal Day 2 and then steeply between Days 5 and 16. The levels of LH-RF were similar in both male and normal female rats until Day 41, after which the increase which had been occurring from Day 16 continued in the male but not the female. In female rats treated with testosterone propionate neonatally ('androgenized females') the hypothalamic content of LH-RF at Day 9 was significantly less than that in the male or normal female, levels reaching those found in the latter two groups by Days 16–22. The lower level of LH-RF in the androgenized female was associated with pituitary gonadotrophin and plasma FSH levels which were lower than in the normal female until Day 30. In the normal female, vaginal opening was associated with a marked drop in hypothalamic LH-RF content and in pituitary LH and FSH, but in the androgenized female, vaginal opening occurred while hypothalamic LH-RF and pituitary LH levels were still rising. The peaks in pituitary FSH and LH and in plasma LH seen on Days 22, 30 and 41, respectively, in the normal female were each delayed by 8–9 days in the androgenized female. In all three types of animal there was a significant drop in plasma FSH between Days 50 and 65 which was associated with a significant increase in pituitary FSH in the male and a significant decrease in pituitary FSH in the androgenized female rats. The day 17 foetal pituitary gland also contained ACTH, and again levels of this hormone rose steeply between Days 5 and 9. In contrast to the gonadotrophins, there was a marked divergence between the pituitary content and concentration of ACTH: content rose while concentration remained relatively steady after Day 9. There was no major difference in pituitary ACTH levels between the three types of animal throughout the study; however, around Days 16 and 50, corticotrophin releasing activity was higher in males and androgenized females compared with that in normal females.
5-ENE-3β-HYDROXYSTEROID DEHYDROGENASE OF HUMAN AND BOVINE ADRENOCORTICAL ENDOPLASMIC RETICULUM: SOLUBILIZATION AND FRACTIONATION
Authors: EASTMAN A. R. , NEVILLE A. M. 
Published: December 2008

SUMMARY
Protein moieties of various molecular sizes and possessing 5-ene-3β-hydroxysteroid dehydrogenase activity have been successfully solubilized from the microsomal membranes of both bovine and human adrenal glands using a combination of Triton X-100 and sonication. These moieties have been studied by gel filtration, sucrose density gradient centrifugation and isoelectric focusing, and were shown to possess a minimum molecular weight of about 118000, with an isoelectric point between 7·2 and 7·4. The molecular weight was dependent upon the concentration of Triton X-100 used during fractionation. No separation of dehydrogenase activities toward the three steroid substrates, pregnenolone, 17α-hydroxypregnenolone and dehydroisoandrosterone, was observed. Changes in the relative activities for the steroid substrates during fractionation were observed, but have been attributed to the formation of allotypes rather than to the existence of separate dehydrogenases with restricted substrate specificity.
SOME EXPERIMENTS ON THE ROLE OF THE FOETAL PITUITARY IN THE MATURATION OF THE FOETAL ADRENAL AND THE INDUCTION OF PARTURITION IN SHEEP
Authors: JONES C. T. , RITCHIE J. W. K. , FLINT A. P. F. 
Published: December 2008

SUMMARY
The effect of repeated increases in plasma ACTH on the production of corticosteroids and androstenedione in the sheep foetus has been investigated. Elevation of foetal plasma ACTH for up to 2 h every 24 h by repeated periods of hypoxia increased the output of cortisol. No consistent effects on foetal or maternal androstenedione concentrations or on maternal oestrogen levels were observed. Repeated short periods of increased foetal plasma ACTH concentration may promote maturation of the foetal adrenal, but there is no increase in androgen secretion by the gland nor is there an increase in oestrogen production by the placenta under such conditions.
THYROTROPHIN RELEASING HORMONE-INDUCED GROWTH HORMONE AND PROLACTIN RELEASE: PHYSIOLOGICAL STUDIES IN INTACT RATS AND IN HYPOPHYSECTOMIZED RATS BEARING AN ECTOPIC PITUITARY GLAND
Authors: PANERAI A. E. , GIL-AD IRIT , COCCHI DANIELA , LOCATELLI V. , ROSSI G. L. , MÜLLER E. E. 
Published: December 2008

SUMMARY
To determine how the sensitivity of the ectopic anterior pituitary gland to the GH-releasing effect of thyrotrophin releasing hormone (TRH) might be affected by the time lapse from transplantation, TRH (0·15 and 0·6 μg) was injected i.v. into hypophysectomized (hypox)-transplanted rats under urethane anaesthesia 1,3, 8,15, 30 and 60 days after transplantation, and plasma samples were taken 5 and 10 min later. Baseline GH values gradually decreased with time from about 16·0 ng/ml (1 day) to about 3·0 ng/ml (30 and 60 days). The TRH-induced GH release was absent 1 day after transplantation, present only with the higher TRH dose 3 and 8 days after transplantation, and clearly elicitable, also with the lower TRH dose (0·15 μg), from 15 up to 60 days. Determination of plasma prolactin concentrations showed a decline from about 85·0 ng/ml (1 day) to about 32·0 ng/ml (8 days); subsequently (15–60 days) prolactin values stabilized. Plasma prolactin levels increased 15 and 60 days after transplantation only when a dose of 0·6 μg TRH was given.
In intact weight-matched rats, TRH induced a GH response only at the dose of 1·2 μg while a short-lived but clear-cut prolactin response could be obtained even with the 0·3 μg dose.
The present results indicate that: (1) disconnexion between the central nervous system and the anterior pituitary gland greatly enhances GH responsiveness while blunting prolactin responsiveness to TRH; (2) the sensitivity of the anterior pituitary gland to the GH-releasing effect of TRH increases with time from transplantation; (3) TRH is a more effective prolactin-than GH-releaser on the pituitary gland in situ.
STEROID RELEASE IN VITRO BY TWO LUTEAL CELL TYPES IN THE CORPUS LUTEUM OF THE PREGNANT SOW
Authors: LEMON MEREDITH , LOIR M. 
Published: December 2008

SUMMARY
Corpora lutea from sows at 30, 60 and 90 days of gestation were dissociated enzymically, and the components of the resulting cell suspension were separated by sedimentation at unit gravity. Two luteal cell populations of 30–50 μm diameter and 15–20 μm diameter were obtained and superfused for up to 18 h with Dulbecco's modified Eagle medium, the cells being supported in a column in a matrix of Biogel. Fractions were collected every 30 min and assayed for progesterone and oestradiol-17β.
At 30 and 60 days of gestation the large luteal cells produced progesterone at an initial rate of approximately 100 ng/h/105 cells, which decreased to half this rate at 90 days. The smaller cells also released progesterone into the medium at approximately 15–20 ng/h/105 cells at all stages of gestation. At 30 days of gestation, neither cell type released significant amounts of oestradiol-17β, but from 60 days onwards, significant and increasing quantities were measured in the superfusates from the larger cells.
Both cell types were perfused with porcine LH at the three stages of gestation, and both showed an immediate response in terms of progesterone release which decreased in magnitude with increasing age of gestation. The response of the smaller cells was greater than that of the larger cells.
EFFECTS OF ANTERIOR HYPOTHALAMIC IMPLANTATION OF GONADAL STEROIDS ON SERUM AND PITUITARY GONADOTROPHINS (FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE) IN THE CASTRATED MALE RAT
Authors: DANGUY A. , ECTORS F. , PASTEELS J. L. 
Published: December 2008

SUMMARY
Castrated rats were stereotaxically implanted with 1 μg oestradiol benzoate, 5 μg testosterone isobutyrate or, as a control, 10 μg cholesterol, in the hypothalamus. The effects of the steroids on plasma and pituitary gonadotrophins (FSH and LH) were assessed by radioimmunoassay. Our results indicate that, in the male rat, in addition to the arcuate nucleus–median eminence complex, the preoptic suprachiasmatic area is able to control synthesis and secretion of both gonadotrophins, and that it is sensitive to oestradiol and testosterone.
USE OF A COMPETITIVE PROTEIN-BINDING ASSAY FOR ADENOSINE 3′:5′-PHOSPHATE FOR THE STUDY OF BOVINE CORPUS LUTEUM ADENYLATE CYCLASE
Authors: YOUNG J. L. , STANSFIELD D. A. 
Published: December 2008

SUMMARY
The use of a competitive protein-binding assay for cyclic AMP, utilizing the binding protein purified from bovine adrenal cortex, for the study of adenylate cyclase activity of the washed 600 g sediment of bovine corpus luteum is validated.
A specific assay for cyclic AMP could only be achieved by removal of the degradation products of ATP on a precipitate of nascent BaSO4. Simple dilution of the sample before assay was not sufficient to eliminate interference from degradation products of ATP.
An observed variability in optimal ATP substrate and tissue concentrations is thought to reflect variability in the enzymic profile of the cyclic corpus luteum. Optima with respect to F−, Mg2+ and pH are more clearly defined and are similar to those reported for adenylate cyclase systems of other tissues.
EXOGENOUS PROGESTERONE: INFLUENCE ON OVULATION AND HORMONE LEVELS IN THE CYCLIC HAMSTER
Authors: GREENWALD G. S. 
Published: December 2008

SUMMARY
The oestrous cycle of the hamster is lengthened by 2 to 3 days when 2·5 or 5·0 mg progesterone are injected on day 1 of the cycle (day of ovulation). Antral follicles develop on day 2 but their growth is significantly retarded in progesterone-treated hamsters. Administration of progesterone is followed within 6 h by an abrupt decline in serum FSH and LH concentration but by day 3 the level of FSH is higher than normal. Serum LH is slower to recover in hamsters receiving 5 mg progesterone but normal levels are also restored by days 3 or 4. Increased serum levels of progesterone are maintained until days 3–5 in animals injected with progesterone.
Despite the presence of antral follicles on day 2 and the fairly prompt restoration of normal levels of gonadotrophins, the serum concentration of oestradiol is suppressed for several days in the progesterone-treated hamster. This suggests that progesterone, in addition to affecting the hypothalamic-pituitary system, may also directly inhibit oestrogen secretion by the antral follicles.
STEROIDS AND PITUITARY RESPONSIVENESS IN FEMALE, ANDROGENIZED FEMALE AND MALE RATS
Authors: FINK G. , HENDERSON S. R. 
Published: December 2008

SUMMARY
Spontaneous gonadotrophin release and the gonadotrophin response to LH releasing factor (RF) were studied in pro-oestrous, androgenized female and male rats. The animals were either intact or gonadectomized (about 32 h previously) and treated with various steroids. The gonadotrophin response (especially LH) was much lower in intact males and androgenized females than in pro-oestrous females. Oestrogen plus progesterone increased plasma gonadotrophin concentrations and responses in ovariectomized rats, but inhibited the increase in the plasma gonadotrophin concentration and the LH response which followed castration in males. As in the normal female, ovariectomy decreased the LH response but increased the plasma FSH concentration and response in the androgenized female; oestrogen and progesterone had relatively little effect. Apart from reducing the postcastration rise in plasma FSH, testosterone had no significant effect in gonadectomized male or female animals. These results show that the effect of steroids on the gonadotrophin response to LH-RF as well as the spontaneous secretion of gonadotrophin depends upon sexual differentiation of the hypothalamo-hypophysial system. Studies with various metabolites of progesterone indicated that the facilitatory action of this steroid could be due, in part, to a 5α-reduced derivative.
HORMONAL EFFECTS OF TAMOXIFEN IN OLIGOSPERMIC MEN
Authors: WILLIS K. J. , LONDON D. R. , BEVIS M. A. , BUTT W. R. , LYNCH S. S. , HOLDER G. 
Published: December 2008

SUMMARY
The hormonal effects of tamoxifen (10 mg daily for 6 months) have been studied in nine men with oligospermia. Basal concentrations of serum LH (1·7 ± 0·1 (s.e.m.) i.u./l) increased to a maximum of 4·1 ± 1·3 i.u./l (P < 0·001) after 6 months, and FSH rose from 4·9 ± 1·0 to a maximum of 7·7 ± 1·3 i.u./l after 4 months of treatment (P < 0·01).
The response to luteinizing hormone releasing hormone (LH-RH) was studied at monthly intervals. Sums of increments of serum LH increased from 35 ± 4 to 92 ± 17 i.u./l at 4 months (P < 0·001) and of FSH from 14 ± 3·4 to 23 ± 3·5 i.u./l at 4 months (P < 0·01).
Basal serum androgens rose from 25 ± 2·7 to 38 ± 2·4 nmol/l after 4 months of treatment (P < 0·05), and serum oestradiol-17β increased from 185 ± 25 to 631 ± 90 pmol/l by 6 months (P < 0·001). No significant changes occurred in sperm counts.
Five normal men acted as controls: they were given tamoxifen for 1 week. No significant changes were observed in serum LH, FSH or release of these hormones following administration of LH-RH. Serum androgens and oestrogens however, increased significantly by day 4 of treatment (P < 0·05).
CAPRINE PLACENTAL LACTOGEN: LEVELS OF PROLACTIN-LIKE AND GROWTH HORMONE-LIKE ACTIVITIES IN THE CIRCULATION OF PREGNANT GOATS DETERMINED BY RADIORECEPTOR ASSAYS
Authors: CURRIE W. B. , KELLY P. A. , FRIESEN H. G. , THORBURN G. D. 
Published: December 2008

SUMMARY
Radioreceptor assays for prolactin-like (lactogenic) activity and growth hormone (GH)-like activity have been used to study concentrations of caprine placental lactogen (PL) in the circulation during pregnancy. Both lactogenic and GH-like activities increased from less than 100 ng/ml (ovine prolactin- and human GH-equivalents) about 60 days after mating to reach peak levels (400–1600 ng/ml) between days 110 and 130 of pregnancy. The levels of both activities increased in essentially the same fashion but during the last 15 days of pregnancy, lactogenic activity declined less than GH-like activity. This divergence was most pronounced at parturition when levels of lactogenic activity increased (∼ 700 ng/ml) despite very low (< 200 ng/ml) levels of GH-like activity being measured and this probably reflected increased secretion of pituitary prolactin near parturition. When serum from a pregnant goat or a simple alkaline extract of placental cotyledons was fractionated on a column packed with Sephadex G-100, lactogenic and GH-like activities eluted together with distribution coefficients of approximately 0·5–0·6. The possibility that caprine PL serves physiologically as a luteotrophin and/or mammotrophin during pregnancy in goats is discussed.
STEROID SEX HORMONES AND PROLACTIN IN POSTMENOPAUSAL WOMEN WITH GENERALIZED MAMMARY CARCINOMA DURING PROLONGED DEXAMETHASONE TREATMENT
Authors: BORKOWSKI A. , L'HERMITE M. , DOR P. , LONGEVAL E. , ROZENCWEIG M. , MUQUARDT C. , VAN CAUTER E. 
Published: December 2008

SUMMARY
The endocrine response to prolonged dexamethasones treatment was investigated in six postmenopausal women with generalized mammary carcinoma. Plasma cortisol levels decreased rapidly and became undetectable whereas significant concentrations of plasma dehydroepiandrosterone and androstenedione persist throughout the study, even in two ovariectomized patients, indicating a certain degree of autonomy or a greater resistance of adrenal 'androgens' to the inhibition of ACTH secretion.
Except in the ovariectomized patients, plasma testosterone did not fall significantly whereas the plasma oestrogens tended progressively towards undetectable concentrations. A similar response was found in six normal postmenopausal women although the disappearance of their oestrogens was relatively rapid. This indicates that much of the testosterone patient after the menopause could still be produced by the ovaries whereas the ovarian production of oestrogens becomes negligible. The delayed disappearance of oestrogens in the patients with mammary carcinoma indicates that the persisting adrenal 'androgens' remained efficient precursors of oestrogen synthesis within the peripheral tissues and presumably within the mammary tumour itself. Plasma dihydrotestosterone behaved like the plasma oestrogens. Despite the fall in plasma oestrogens, plasma gonadotrophins did not increase further but plasma prolactin rose progressively.
The persistence of steroid sex hormones and the rise of plasma prolactin might explain the poor response to dexamethasone treatment in mammary carcinoma.
PROLACTIN AND LUTEINIZING HORMONE LEVELS BEFORE AND AFTER PARTURITION IN RATS BEARING EITHER SINGLE OR MULTIPLE EMBRYOS
Authors: NIR I. , GOLDHABER G. , HIRSCHMANN N. , SHANI J. 
Published: December 2008

SUMMARY
Levels of prolactin and LH were determined in serum and pituitary during the last days of pregnancy and post partum in rats bearing single and multiple embryos. In rats with a single embryo serum prolactin and LH levels were significantly lower during the last 2 days of pregnancy and post partum than in rats bearing multiple embryos. While large increases were recorded in serum prolactin and LH levels in the rats with multiple embryos between days 21 and 22 of gestation, in the group with single embryos changes occurred in LH level only. Throughout the experiment pituitary prolactin was lower in rats with a single embryo than in those with multiple embryos in spite of the sharp drop in prolactin level in the group with multiple embryos from day 21 to 22. No differences were observed in the pituitary LH levels of either group during the days preceding parturition, but in the rats with multiple embryos there was a sharp drop in LH level post partum. It seems that the reduced serum prolactin level in the rats with a single embryo was associated with inhibition of pituitary prolactin synthesis and release, whereas the decreased serum LH level resulted from impaired release but not synthesis. These results support the hypothesis of a regulatory role for the placenta in pituitary prolactin and LH synthesis and release, either by hypothalamus– pituitary stimulation, or perhaps by way of the ovaries, through regulation of ovarian steroid production.
ENDOCRINE REGULATION OF SEX-DEPENDENT HYDROXYSTEROID DEHYDROGENASE ACTIVITIES IN RAT KIDNEY: NADP-DEPENDENT MICROSOMAL 3α- AND 20β-HYDROXYSTEROID DEHYDROGENASE
Authors: GHRAF R. , LAX E. R. , WAGNER W. , SCHRIEFERS H. 
Published: December 2008

SUMMARY
The NADP-dependent microsomal kidney enzymes, 3α- and 20β-hydroxysteroid dehydrogenase (HSDH), which exhibit considerable sex differences in their activities (male: female activity ratios, 16:1 and 30:1 respectively), were investigated after interference with the pituitary–gonad and pituitary–adrenal systems.
Prepubertal gonadectomy as well as hypophysectomy of mature male rats led to a decline in HSDH activity to almost that found in the normal female rat, whereas activities in female rats were unaffected. Testosterone induced typical male 3α-HSDH activity in both gonadectomized and hypophysectomized rats of either sex. Administration of 5α-dihydrotestosterone (5α-DHT) or 5α-androstane-3α, 17β-diol to hypophysectomized male rats was equally effective in restoring full 3α- and 20β-HSDH activities whereas 5α-androstane-3β, 17β-diol was less effective and dehydroepiandrosterone was ineffective. Simultaneous administration of cyproterone acetate did not block the inductive action of 5α-DHT.
Administration of chorionic gonadotrophin, pregnant mare serum gonadotrophin or a combination of luteinizing hormone and follicle-stimulating hormone to hypophysectomized male rats all led to parallel increases in the weight of the seminal vesicles and in both renal enzyme activities; administration of growth hormone, prolactin or thyroid-stimulating hormone was ineffective.
Adrenalectomy of gonadectomized, but not of hypophysectomized male rats, caused a further drop in activity to the normal female level. Adrenalectomy of otherwise intact rats did not affect either enzyme activity.
The hypophysis was involved in the regulation of the two NADP-dependent renal HSDH activities through its gonadotrophic function in male rats; adrenal secretions were of little physiological significance.
INFLUENCE OF FOETAL GENOTYPE ON THE FOLLICLE-STIMULATING HORMONE:LUTEINIZING HORMONE RATIO OF PREGNANT MARE SERUM GONADOTROPHIN
Authors: STEWART FRANCESCA , ALLEN W. R. , MOOR R. M. 
Published: December 2008

SUMMARY
Rat testicular radioreceptor assays specific for FSH and LH were used to determine the FSH: LH ratio of PMSG produced by horse, donkey, mule and hinny conceptuses. Measurements of FSH and LH activities in PMSG produced both in vivo and in vitro by the four types of conceptuses showed that the genotype of the foetus markedly influences the FSH: LH ratio of PMSG. The FSH: LH ratio of PMSG produced by the horse conceptus was around unity whereas the ratio of PMSG produced by the donkey conceptus was as low as 0·2. Furthermore, the hybrid mule and hinny conceptuses both produced PMSG with an FSH: LH ratio which was approximately midway between those of the horse and donkey.
PITUITARY REGULATION OF LEYDIG CELL FUNCTION IN THE ADULT MALE RAT
Authors: HAUGER R. L. , CHEN Y.-D. I. , KELCH R. P. , PAYNE A. H. 
Published: December 2008

The effects of hypophysectomy on serum testosterone, 125I-labelled hCG binding to testicular membranes and on testicular responsiveness were studied in adult rats. Serum testosterone decreased rapidly over the first 6 h after hypophysectomy. LH receptors were determined (pmol/testis) by measuring the specific binding of 125I-labelled hCG in membrane preparations of testes of rats hypophysectomized 1, 2, 3, 6, 9, or 15 days earlier. Hypophysectomy did not result in a decrease in 125I-labelled hCG binding on day 1 but this had decreased to 40% of that in intact controls by day 2. A gradual decline was found between days 2 and 6 at which time hCG binding had decreased to 15%. No further decrease occurred between days 6 and 15. Scatchard analysis indicated that the decline in hCG binding was due to a decrease in binding capacity and not to a decrease in binding affinity. FSH, testosterone, dihydrotestosterone, and oestradiol were unable to prevent the decline in hCG binding. Although serum testosterone, testicular testosterone content, and 125I-labelled hCG binding decreased rapidly after hypophysectomy, testicular responsiveness to LH was biphasic. The intraperitoneal administration of 25 μg LH 2 h before decapitation increased testosterone in the circulation to a greater extent in animals hypophysectomized for 1 day than in intact controls while hCG binding affinities and capacities had not changed. Two or three days after hypophysectomy testicular responsiveness to LH was similar to that of intact controls even though hCG binding in hypophysectomized animals had decreased to 40 and 28% of intact controls respectively.
It is concluded that (1) the testis is dependent on anterior pituitary hormones for maintenance of testicular LH receptors and testosterone secretion, (2) FSH, testosterone, dihydrotestosterone, or oestradiol cannot prevent the decline in testicular LH receptors resulting from hypophysectomy, and (3) steroidogenic capacity of the testis persists significantly longer than the hCG binding capacity of the testis.