bluuebunny/crossref_metadata_2025_split huggingface dataset:
PRIMING EFFECT OF LUTEINIZING HORMONE RELEASING FACTOR ELICITED BY PREOPTIC STIMULATION AND BY INTRAVENOUS INFUSION AND MULTIPLE INJECTIONS OF THE SYNTHETIC DECAPEPTIDE
Authors: FINK G. , CHIAPPA S. A. , AIYER M. S. 
Published: December 2008

SUMMARY
We have investigated whether the priming effect of LH-RF can be elicited by electrical stimulation of the medial preoptic area, or by i.v. infusion or multiple i.v. injections of the synthetic decapeptide. All experiments were carried out on animals anaesthetized with sodium pentobarbitone at 13.30 h. In pro-oestrous rats, the LH response to the second of two electrical stimuli, 15 min in duration and separated by 60 min, was significantly greater than the response to the first stimulus. When synthetic LH-RF was infused at a constant rate for 90 min, plasma LH increased gradually for the first 45–60 min after which it increased markedly. This enhanced secretion of LH did not occur in rats which were infused with the same total dose of LH-RF, either 15 or 75 ng/100 g body wt, over periods of 45 min or less. When a dose of 15 ng LH-RF/100 g body wt was administered in six divided doses by i.v. injections, each separated by 15 min, there was a marked increase in plasma LH after 75 min. The profile of the mean plasma LH concentration in rats subjected to preoptic stimulation for 90 min was similar to that in rats infused for 90 min with LH-RF, but the variation in response was much greater in the stimulated rats.
These results indicate that the priming effect can be elicited by endogenous as well as synthetic LH-RF, and that whether LH-RF reaches the pituitary at a constant rate or in a pulsatile manner the factor is capable of significantly increasing the responsiveness of the gonadotrophs. The relevance of these findings with respect to the development of the spontaneous preovulatory LH surge is discussed. A priming effect could not be elicited by constant LH-RF infusion in dioestrous rats; this supports the view that steroid hormones, especially oestradiol-17β, determine the magnitude of the effect. The LH response in male rats subjected to i.v. infusion of LH-RF was much lower than in females. Pre-treatment with oestradiol benzoate did not increase the response significantly, suggesting that this sex difference cannot be ascribed simply to low levels of plasma oestrogen in the male.
EFFECT OF GUANYL NUCLEOTIDES ON PARATHYROID HORMONE-RESPONSIVE ADENYLATE CYCLASE IN CHICK KIDNEY
Authors: HUNT N. H. , MARTIN T. J. , MICHELANGELI V. P. , EISMAN J. A. 
Published: December 2008

SUMMARY
Both guanosine 5′-triphosphate (GTP) and 5′-guanylylimidodiphosphate (Gpp(NH)p) activated adenylate cyclase (EC 4.6.1.1) in chick kidney plasma membranes. Half-maximal stimulation occurred at 3·1 × 10−6 m for both agents. The maximum increases in adenylate cyclase activity produced by GTP and Gpp(NH)p were respectively 130 and 720% over basal activity.
At the end of a 12 min incubation period GTP concentration was 85% of that originally added in the presence of an ATP-regenerating system but less than 20% in its absence.
GTP and guanosine 5′-diphosphate inhibited the activation of adenylate cyclase by Gpp(NH)p, suggesting that they all acted at a common site. Gpp(NH)p facilitated the stimulation of adenylate cyclase activity by bovine parathyroid hormone (BPTH) and by the synthetic amino terminal fragment BPTH (1–34), decreasing the concentrations required for half-maximal enzyme activation by a factor of approximately eight in both cases. This property was not shared by the native nucleotide GTP. Gpp(NH)p rendered active (at certain concentrations) a synthetic parathyroid hormone peptide fragment, BPTH (2–34), which was incapable of activating adenylate cyclase in the absence of the nucleotide analogue. This suggested that the GTP analogue, in addition to a direct effect upon adenylate cyclase activity, was capable of influencing hormone interaction with the enzyme complex.
ROLE OF THE THYROID GLAND IN REGULATION OF METABOLIC RATE IN AN AIR-BREATHING SILUROID FISH, HETEROPNEUSTES FOSSILIS (BLOCH)
Authors: PANDEY B. N. , MUNSHI J. S. D. 
Published: December 2008

SUMMARY
Studies on cyclic activity of the thyroid and seasonal variations in oxygen consumption (V̇o2) under experimental conditions in which surfacing was either allowed or prevented were made in H. fossilis to try to establish a relationship between these measures and to ascertain the possible role of the thyroid in the regulation of metabolic rate. A good correlation was found between the activity of the thyroid and V̇o2 in this species. This finding was further confirmed by the administration of l-thyroxine or thiouracil to this fish. The thyroxine-and thiouracil-treated animals showed significantly higher (P < 0·05) and lower (P < 0·01) rates of V̇o2 respectively, thus indicating the probable role of the thyroid in the regulation of metabolic rate.
SUPPRESSION OF LUTEINIZING HORMONE RELEASE BY 5α-ANDROSTANE-3α,17β-DIOL AND ITS 3β EPIMER IN IMMATURE OVARIECTOMIZED RATS
Authors: ECKSTEIN B. , YEHUD S. , SHANI J. , GOLDHABER G. 
Published: December 2008

SUMMARY
The effect of 5α-androstane-3α,17β-diol, its 3β epimer and oestradiol benzoate on suppression of LH release after ovariectomy was studied in immature rats. At doses of 50 and 100 μg/100 g body weight/day the 3α compound suppressed LH release after ovariectomy to the same extent as 0·1 μg oestradiol benzoate/100 g/day. 3α-Androstanediol at a dose of 25 μg/100 g/day suppressed LH release only up to day 45 of life, while the same dose of the 3β epimer had no effect on LH suppression. The effect of 3β-androstanediol on inducing precocious vaginal opening was found to be mediated by the ovaries, since it was eliminated by ovariectomy. These results confirm our previous findings on the participation of androstanediol in the normal regulation of LH and in the mechanism of onset of puberty in the rat.
DEVELOPMENT AND APPLICATION OF A HETEROLOGOUS RADIOIMMUNOASSAY FOR OVINE FOLLICLE-STIMULATING HORMONE
Authors: McNEILLY JUDITH R. , McNEILLY A. S. , WALTON J. S. , CUNNINGHAM F. J. 
Published: December 2008

SUMMARY
A highly specific and sensitive heterologous double antibody radioimmunoassay for ovine follicle-stimulating hormone (oFSH) is described in detail. The assay using a rabbit antiserum to human FSH and either 125I-labelled rat FSH or 125I-labelled oFSH as tracer is specific for FSH. A maximum cross-reaction (B/Bo = 50%) of 0·1% was observed with other ovine, rat or human pituitary hormones or human chorionic gonadotrophin. Serum levels of oFSH in samples collected daily throughout the oestrous cycle showed large individual variations. In five out of nine animals a peak of FSH was observed on the day of oestrus.
CHANGES IN ADRENOCORTICAL FUNCTION IN MALE AND FEMALE GUINEA-PIGS DURING MATURATION
Authors: GREINER J. W. , KRAMER R. E. , COLBY H. D. 
Published: December 2008

SUMMARY
Adrenal cortisol secretion is greater in female than male guinea-pigs and declines with maturation in animals of both sexes. In an attempt to determine the intra-adrenal mechanisms responsible for age and sex influences on corticosteroid output, adrenocortical enzyme activities were compared in sexually immature (3 weeks) and mature (17 weeks) animals. Adrenal mitochondrial protein concentration decreased with maturation in male and female guinea-pigs. 11β-Hydroxylase activity in adrenal mitochondria was also lower in mature than immature guinea-pigs but greater in males than females. Neither mitochondrial cytochrome P-450 concentration nor cholesterol side-chain cleavage activity varied with age or sex. Adrenal microsomal protein concentration and 21-hydroxylase activity were similar in male and female guinea-pigs of the same age but far greater in mature than immature animals. Microsomal cytochrome P-450 concentration was unaffected by age or sex. Adrenal Δ4-steroid (cortisol) hydrogenase activity increased with maturation in both male and female guinea-pigs and was higher in males than females. These observations indicate that cortisol secretion, as modified by age and sex, correlates closely with adrenal steroid reductive but not oxidative metabolism, suggesting that changes in Δ4-hydrogenase activity are responsible, at least in part, for the decline in adrenal secretion during maturation in guinea-pigs.
ADSORPTION OF FREE STEROIDS WITH CHARCOAL-GELATIN DISKS IN RADIOIMMUNOASSAYS
Authors: SABA N. 
Published: December 2008

SUMMARY
The preparation of charcoal–gelatin disks and their use for removing free steroid in radioimmunoassays are described. Plasma concentrations of several steroids were determined using charcoal–gelatin disks or charcoal suspension and the results are compared. The advantages of using charcoal–gelatin disks are discussed.
EFFECTS OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE ON OVARIAN CYCLIC AMP AND PROSTAGLANDIN E IN VIVO IN RATS TREATED WITH INDOMETHACIN
Authors: RIGLER G. L. , PEAKE G. T. , RATNER A. 
Published: December 2008

SUMMARY
The role of prostaglandins in both FSH- and LH-mediated increases in ovarian cyclic AMP was examined in rats in vivo. Dose-related increases in ovarian cyclic AMP levels were observed 10 min after intravenous injection of FSH or LH. No changes in ovarian prostaglandin E (PGE) content were detected after injection of either gonadotrophin at doses which substantially enhanced cyclic AMP accumulation. Prior treatment of rats with indomethacin produced a greater than 50% decrease in ovarian PGE levels, but did not prevent the FSH- or LH-induced rise in ovarian cyclic AMP concentration. These in vivo experiments do not support the concept that PGE plays a role as an obligatory mediator for the gonadotrophin-induced rise in ovarian cyclic AMP levels.
ADMINISTRATION OF ANTISERUM AGAINST OVINE FOLLICLE-STIMULATING HORMONE OR OVINE LUTEINIZING HORMONE AT PRO-OESTRUS IN THE RAT: EFFECTS ON FOLLICULAR DEVELOPMENT DURING THE ONCOMING CYCLE
Authors: WELSCHEN R. , DULLAART J. 
Published: December 2008

SUMMARY
Cyclic rats received at 13.00 h on the day of pro-oestrus a single i.v. injection of one of the following antiserum preparations: AOLH (raised in rabbits against NIH-LH-S17); AOFSH (raised against NIH-FSH-S9) or pAOFSH (AOFSH preincubated with 195 μg NIH-LH-S16/ml). Rats were killed at day 1, 3 or 5 after injection, and the ovaries prepared for histological study of the antral follicles.
After AOLH, ovulation and resumption of meiosis in oocytes in pre-ovulatory follicles were prevented but follicular development during the following cycle appeared undisturbed. After either AOFSH or pAOFSH, blockade of ovulation was never observed but the formation of antral follicles normally occurring between mid-pro-oestrus and mid-oestrus was postponed by about one day. The later development of antral follicles might reflect a supranormal compensatory secretion of endogenous gonadotrophin because the development does not occur in AOFSH- or pAOFSH-treated rats hypophysectomized 24 h after injection and subsequently treated with pregnant mare serum gonadotrophin in dosage approximating the amount of gonadotrophin secreted endogenously during dioestrus.
The results imply (1) that the pre-ovulatory surge of LH release is not essential for follicular development during the oncoming cycle whereas (2) a surge of FSH release is required for the formation of the new cohort of antral follicles that is normally seen at the start of a new cycle.
PURIFICATION AND CHARACTERIZATION OF LEYDIG CELLS FROM RAT TESTES
Authors: JANSZEN F. H. A. , COOKE B. A. , VAN DRIEL M. J. A. , VAN DER MOLEN H. J. 
Published: December 2008

SUMMARY
An LH-responsive Leydig cell preparation (containing 6 ± 2% Leydig cells) was obtained by collagenase treatment of rat testis. Centrifugation of this cell preparation through a 13% Ficoll solution for 10 min at 1500 g resulted in a four times purification of the Leydig cells, with a concomitant increase in steroidogenic activity. Addition of 0·2% albumin to the 13% Ficoll solution, adjusted to 280 mosmol/l, resulted in a further twofold purification of the Leydig cells paralleled by a twofold increase in steroidogenic activity. Centrifugation of these Ficoll-albumin-purified Leydig cells through a 6% dextran solution for 2 min at 100 g resulted in a further 1·7 times purification of the Leydig cells. A combination of the two centrifugation steps resulted in a 12·5 times purification of Leydig cells compared with the original crude cell suspension, while an increase in steroidogenic activity of 22·5 times was obtained. This final cell preparation contained 59 ± 17% Leydig cells (mean ± s.d., n = 6). The recovery of Leydig cells was 29%.
Collagenase treatment of testes deficient in spermatogenesis resulted in a cell preparation with the same steroidogenic activity as Ficoll-purified cells from normal testes. Centrifugation of these cells through a 13% Ficoll solution gave only a limited increase in the steroidogenic activity. Isopycnic centrifugation of the crude cell preparation on a discontinuous Ficoll metrizoate gradient resulted in two discrete peaks of Leydig cells, one peak at a density of 1·039–1·055 g/ml and one at a density of 1·068–1·088 g/ml. Both types of cells produced testosterone. In the presence of LH, cyclic AMP production in both types of Leydig cells increased, but testosterone production was only increased by LH in the 'denser' Leydig cells and not in the 'light' Leydig cells.
No difference in sensitivity to LH could be observed between the Leydig cell preparations of different purity. Using a 60 min pre-incubation period the highest testosterone response was obtained with 100–1000 ng LH/ml. The same maximum testosterone response was obtained with 10–100 ng LH/ml when the pre-incubation period was omitted.
EFFECT OF THE ANTI-OESTROGEN TAMOXIFEN ON PLASMA LEVELS OF LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, PROLACTIN, OESTRADIOL AND PROGESTERONE IN NORMAL PRE-MENOPAUSAL WOMEN
Authors: GROOM G. V. , GRIFFITHS K. 
Published: December 2008

SUMMARY
Plasma levels of LH, FSH, prolactin, oestradiol and progesterone were determined daily during two consecutive menstrual cycles in six women volunteers. During the first (control) cycle no treatment was given and normal secretion of these hormones was observed. Oral administration of tamoxifen (20 mg/day), for either 5 or 10 days of the follicular phase of the second cycle, caused no change in either the overall length of the cycle or the time of occurrence of the mid-cycle gonadotrophin surge. There was little difference in the secretion of LH, FSH and progesterone during the control and test cycles.
A two- to eight-fold increase in oestradiol levels was observed during the test cycle which was most pronounced at the times of mid-cycle and mid-luteal hormone peaks. There was a significant decrease in plasma prolactin levels at mid-cycle but no real difference could be seen during the remainder of the cycle.
The data suggest that tamoxifen may act directly on the ovary to stimulate oestradiol release without intermediary gonadotrophin stimulation. As the drug apparently inhibited prolactin secretion even in the presence of high oestradiol levels, an alternative explanation may be that the reduced prolactin concentration permits augmented ovarian stimulation by normal concentrations of gonadotrophins.
EFFECT OF THYROID STATUS ON THE THYROTROPHIN-RELEASING HORMONE-DEGRADING ACTIVITY OF RAT SERUM
Authors: WHITE N. , JEFFCOATE S. L. , GRIFFITHS E. C. , HOOPER K. C. 
Published: December 2008

SUMMARY
The TRH-degrading activity of rat serum in vitro is five times more potent than that of human serum. In rats, it is significantly reduced in hypothyroidism (thiouracil-induced) and significantly increased in hyperthyroidism (T3 or T4-induced). This suggests a possible role in the regulation of adenohypophysial-thyroid function which is probably, in turn, dependent on thyroid hormone, rather than TSH, levels.
ANDROGEN LEVELS IN THE PLASMA AND PROSTATIC TISSUES OF PATIENTS WITH BENIGN HYPERTROPHY AND CARCINOMA OF THE PROSTATE
Authors: HABIB F. K. , LEE I. R. , STITCH S. R. , SMITH P. H. 
Published: December 2008

SUMMARY
Specific radioimmunoassays for testosterone, dihydrotestosterone (DHT) and androstenedione were carried out to measure the concentrations of the three hormones in the plasma and prostatic tissue of ten patients with benign prostatic hypertrophy (BPH) and ten patients with carcinoma of the prostate.
The results indicate that there are no significant differences between the peripheral plasma concentrations of testosterone, DHT and androstenedione in BPH [19·7 ± 2·6, 2·6 ± 0·9 and 5·5 ± 1·7 (s.e.m.) nmol/l respectively] and in carcinoma 16·9 ± 2·8, 2·4 ± 0·5, 4·4 ± 1·1 nmol/l respectively], (in all cases P > 0·1). In contrast, the prostate tissue ratios DHT: testosterone (3·59 ± 0·55 for BPH and 0·66 ± 0·09 for carcinoma) and androstenedione: testosterone (2·83 ± 0·38 for BPH and 1·07 ± 0·16 for carcinoma) are significantly less in carcinoma than in benign hypertrophy (in all cases P < 0·01).
The accumulation of testosterone in the carcinoma, relative to values found in BPH tissue is, therefore, not associated with changes in the concentrations of androgens in the plasma pool but may be related to local factors and metabolic changes within the prostate.
GLYCEROL RELEASE IN VITRO FROM ADIPOSE TISSUE OF OBESE (ob/ob) MICE TREATED WITH THYROID HORMONES
Authors: OTTO W. , TAYLOR T. G. , YORK D. A. 
Published: December 2008

SUMMARY
Glycerol release from adipose tissue of adult genetically obese (ob/ob) mice was greater than that from adipose tissue of lean litter-mates. However, a higher concentration of adrenaline was required to stimulate lipolysis in ob/ob adipose tissue. Since oxygen consumption and the uptake of radioactive iodine by the thyroid were reduced and the biological half-life of thyroidal radio-iodine was lengthened, it is suggested that ob/ob mice are hypothyroid. The poor sensitivity of ob/ob adipose tissue to low doses of adrenaline was improved by treatment with either tri-iodothyronine or thyroxine. The lipolytic responses to both dibutyryl 3′:5′-cyclic adenosine monophosphate and aminophylline were enhanced in thyroid hormone-treated lean and ob/ob mice. A higher dose of tri-iodothyronine was required to enhance lipolysis in ob/ob mice than in lean controls. The possibility that hypothyroidism is responsible for the change in response of ob/ob adipose tissue to lipolytic hormones is discussed.
ANDROSTANEDIOL SULPHATES IN PERIPHERAL BLOOD OF IMMATURE RATS AND SOME OF THEIR BIOLOGICAL EFFECTS
Authors: RAVID RIVKA , ECKSTEIN BENJAMIN 
Published: December 2008

SUMMARY
The conjugation of 5α-androstane-3α,17β-diol (3α-A) and its 3β epimer (3β-A) was determined in the peripheral blood of immature female rats. About two thirds of these steroids were present in blood as sulphates and one third as glucuronides; no free steroids were detected. Administration of 3β-A sulphate (25 μg/100 g body weight/day) and of 3α-A sulphate (50 μg/100 g/day) from day 21 of life until the day of vaginal opening, advanced the day of the first ovulation. Administration of the 3β-A sulphate did not induce precocious vaginal opening whereas the free alcohol was active in this respect. Implantation of 3β-A sulphate, but not of the 3α epimer, into the basal medial hypothalamus resulted in the death of all animals within 24 h.
VASOPRESSIN RELEASE DURING VENTRICULO-CISTERNAL PERFUSION WITH PROSTAGLANDIN E2 IN THE DOG
Authors: YAMAMOTO MANABU , SHARE L. , SHADE R. E. 
Published: December 2008

SUMMARY
In an attempt to determine whether prostaglandin E2 (PGE2) can act centrally to affect the release of vasopressin (ADH), the ventriculo-cisternal system of anaesthetized dogs was perfused with PGE2. When PGE2 was perfused at a rate of 76·4 ng/min (0·19 ml/min), the plasma ADH concentration was unchanged. However, perfusion of PGE2 at a rate of 152·8 ng/min (0·19 ml/min) resulted in a significant increase in the plasma ADH concentration from the control value of 9·0 ± 2·2 (s.e.m.) to 18·8 ± 3·9 μu./ml at 10 min and to 41·0 ± 16·7 μu./ml at 30 min after the start of the perfusion. There were no changes in arterial blood pressure, rectal temperature, plasma osmolality, and the plasma concentrations of sodium and potassium. In additional experiments, i.v. injection of indomethacin (2 or 20 mg/kg) decreased the plasma ADH concentration by approximately 50%. Although this finding is consistent with a role of PGE2 in the control of ADH release, it could also have been due to the observed increases in arterial blood pressure and effective left atrial pressure. Plasma renin activity was unchanged in the indomethacin experiments. It is concluded that PGE2 can act in the central nervous system to stimulate ADH release.
PLASMA CONCENTRATION OF ANDROSTENEDIONE DURING THE BOVINE OESTROUS CYCLE
Authors: KANCHEV L. N. , DOBSON HILARY 
Published: December 2008

SUMMARY
A radioimmunoassay with Sephadex chromatography for androstenedione is described. Concentrations of androstenedione in bovine peripheral blood during the oestrous cycle ranged from 80 to 100 pg/ml. There was considerable variation and no pattern suggestive of physiological significance emerged, unlike those of oestradiol and testosterone.
CONTROL OF GLYCOLYTIC ENZYMES BY ANDROGENS IN THE RAT EPIDIDYMIS
Authors: BROOKS D. E. 
Published: December 2008

SUMMARY
The influence of steroids on the specific activities of glycolytic enzymes was studied in the caput and cauda epididymidis of the rat. In castrated animals, increases in enzyme activities were induced by the administration of androgenic steroids whilst oestradiol and progesterone were without effect. On the other hand, the 'antiandrogenic' steroid, cyproterone acetate (16 mg/kg per day for 2 weeks) did not cause a decrease in enzyme activities when administered to animals with ligated efferent ducts. Not all glycolytic enzymes responded to androgens, but more enzymes responded in the caput than in the cauda epididymidis. Administration of testosterone propionate to castrated animals demonstrated that maximum enzyme activity was produced at a dose of 0·1 mg/kg per day whilst higher doses were required to achieve maximum weight of the epididymis, seminal vesicles and prostate. Following castration of animals with ligated efferent ducts, no changes in enzyme activities were observed for approximately 2 days, but then activities declined over the next 2 weeks. When testosterone propionate was administered to castrated animals, a similar lag of approximately 2 days occurred before enzyme activities began to increase.
CHANGES IN UTERINE AND OVARIAN BLOOD FLOW DURING THE OESTROUS CYCLE IN RATS
Authors: HARVEY CAROL A. , OWEN D. A. A. 
Published: December 2008

SUMMARY
The rates of uterine and ovarian blood flow during the oestrous cycle in rats were measured using radioactive microspheres. Blood flow was highest in the ovaries and uteri during pro-oestrus and lowest during metoestrus. During pro-oestrus, mean ovarian blood flow was 676·2 ± 183·6 (s.d.) ml/min/100 g wet tissue and mean uterine blood flow was 249·7 ± 120·1 ml/min/100 g. During metoestrus mean ovarian blood flow was 117·4 ± 19·8 ml/ min/100 g and mean uterine blood flow was 38·5 ± 7·4 ml/min/100 g. In ovariectomized rats, uterine blood flow was 28·7 ± 10·5 ml/min/100 g.
STUDIES ON OVINE PLACENTAL LACTOGEN SECRETION BY HOMOLOGOUS RADIOIMMUNOASSAY
Authors: HANDWERGER S. , CRENSHAW C. , MAURER W. F. , BARRETT JANET , HURLEY T. W. , GOLANDER A. , FELLOWS R. E. 
Published: December 2008

SUMMARY
The concentrations of ovine placental lactogen (oPL) have been determined in maternal plasma, umbilical cord plasma, and allantoic fluid by an homologous radioimmunoassay for oPL which is sensitive to 0·1 ng hormone. Ovine placental lactogen was first detected in maternal plasma at 41–50 days of gestation and reached a peak concentration of 2547 ± 226 (s.e.m.) ng/ml at 121–130 days in ewes with singleton gestations. The oPL concentration in cord plasma was 336·4 ± 60·3 ng/ml and in allantoic fluid was 29·6 ± 6·4 ng/ml. After surgical removal of the placenta, oPL disappeared from maternal plasma with a half-life of 29·1 ± 1·3 min.