bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF SYNTHETIC THYROTROPHIN RELEASING FACTOR ON PROLACTIN AND LUTEINIZING HORMONE SECRETION IN MALE AND FEMALE RATS DURING VARIOUS REPRODUCTIVE STATES
Authors: DEIS R. P. , ALONSO NIA 
Published: December 2008

SUMMARY
The effect of synthetic thyrotrophin releasing factor (TRF) on serum prolactin and LH concentrations was determined by radioimmunoassay in male, cyclic and pseudopregnant female rats. A solution of TRF (0·1, 0·25, 0·5 and 1 μg/rat) was injected i.v. at 17.00 h into rats pretreated with sodium pentobarbitone at 13.00 h. A group of male rats was also treated with TRF at 11.00 h after pretreatment with sodium pentobarbitone at 07.00 h. Fifteen minutes after TRF administration, blood samples were obtained by heart puncture. Doses of 0·25, 0·5 and 1 μg TRF significantly increased the serum prolactin concentration in pro-oestrous rats. The mean serum prolactin level after the injection of 0·5 and 1 μg into oestrous rats and 0·5 μg TRF into dioestrous day 2 rats, was significantly greater than the control values. Injection of TRF on day 1 of dioestrus had no effect. Serum LH concentration was not significantly modified by the various doses of TRF administered. On day 3 of pseudopregnancy a significant increase of serum prolactin values was obtained with 0·5 and 1 μg TRF. On day 7 of pseudopregnancy a dose of 0·5 μg produced the same effect, but on day 10 of pseudopregnancy only 1 μg TRF significantly increased serum prolactin levels when compared with the control rats. In male rats serum prolactin concentration was significantly greater than the control values after TRF treatment either in the morning or the afternoon. The response was similar to that obtained in pro-oestrous rats. The results suggest that the ability of synthetic TRF to stimulate prolactin release exists in both female and male rats and that TRF does not affect LH secretion.
CYTOPLASMIC OESTROGEN RECEPTOR COMPLEX OF FEMALE OVINE PITUITARY: CHANGES ASSOCIATED WITH THE REPRODUCTIVE STATE AND OESTRADIOL TREATMENT
Authors: WISE P. M. , PAYNE A. H. , KARSCH F. J. , JAFFE R. B. 
Published: December 2008

SUMMARY
Binding of oestrone and oestradiol to a pituitary cytosol receptor was studied in ovariectomized sheep during the breeding season, during anoestrus and after oestradiol treatment during anoestrus. All sheep were ovariectomized 2 weeks before removal of the anterior pituitary. Oestrogen treatment consisted of the subcutaneous implantation of Silastic capsules containing oestradiol-17β 3 weeks before ovariectomy. Association constants (KA) for oestrone and oestradiol and the concentration of binding sites for oestradiol varied with changes in reproductive state. Oestradiol bound more tightly and the concentration of available binding sites was lower during the breeding season than during anoestrus. The affinity of oestrone binding was less during the breeding season than during anoestrus, whilst the concentration of binding sites for this steroid did not change with changes in reproductive state. Treatment of anoestrous sheep with oestradiol increased the KA for oestradiol and decreased the concentration of binding sites. However, no effect of oestradiol treatment was observed with regard to the KA or concentration of binding sites for oestrone. The results suggest that either the pituitary oestrogen cytoplasmic receptor undergoes a conformational change during the breeding season causing oestradiol to be more tightly bound or the onset of the breeding season is accompanied by the appearance of a new receptor which binds to oestradiol with greater affinity. Oestradiol treatment of anoestrous sheep mimics this change.
IMMUNOREACTIVE GASTRIN IN DIFFERENTIAL AND DENSITY GRADIENT FRACTIONS OF RAT GASTRIC MUCOSA
Authors: TROTMAN C. N. A. , FIDDES I. J. S. , GRUND E. R. , McHANWELL S. , SANDERS D. J. , SANDERSON CATHERINE , SHAW B. 
Published: December 2008

SUMMARY
Immunoreactive gastrin was measured in subcellular fractions of rat gastric mucosa. The sedimentational properties of subcellular gastrin-containing structures were distinct from those of mitochondria. After centrifugation in sucrose density gradients using a zonal rotor, the peak of immunoreactive gastrin was found in 1·17–1·18 g cm−3 density sucrose (1·35 m; 39·5%, w/w). A thermolabile component with 125I-labelled gastrin-binding activity present in gastric mucosal homogenates and fractions was not associated with the gastrin storage vesicles sedimenting in density gradients.
IMMUNOREACTIVE LUTEINIZING HORMONE RELEASING FACTOR IN RAT PITUITARY STALK BLOOD: EFFECTS OF ELECTRICAL STIMULATION OF THE MEDIAL PREOPTIC AREA
Authors: FINK G. , JAMIESON M. G. 
Published: December 2008

SUMMARY
Blood was collected from the cut pituitary stalk of male and female rats before and during the application of an electrical stimulus to the medial preoptic area. The plasma was assayed for immunoreactive LH releasing factor (RF) by a double antibody radioimmunoassay using a specific antiserum raised in rabbits against the free acid derivative of the decapeptide LH-RF conjugated to bovine serum albumin. The decapeptide (used as a standard) and pituitary stalk plasma cross-reacted in a similar manner with the antiserum. Stimulation of the preoptic area increased significantly the amount of LH-RF in pituitary stalk plasma in both male and female rats. The increase in LH-RF was linearly related to the strength of the stimulating current, and the amount of LH-RF liberated diminished on cessation of the stimulus. The concentration of LH-RF in pituitary stalk plasma from female rats was significantly greater than that in jugular venous plasma.
The magnitudes of the mean increments of LH-RF in pituitary stalk plasma (stimulation minus pre-stimulation values) at various times of the oestrous cycle in female rats suggests that between 18.00 h of dioestrus and 13.00 h of pro-oestrus there is an increase in sensitivity of the LH-RF secretory mechanism to electrical stimulation. However, the increments decreased in magnitude between 13.00 and 18.00 h of pro-oestrus, indicating that the marked increase in responsiveness of the hypothalamo-hypophysial system to electrical stimulation which occurs during this period is due mainly to a change in sensitivity of the pituitary gonadotrophs to LH-RF.
The LH-RF in pituitary stalk plasma collected before application of the stimulus was higher at some of the times examined during pro-oestrus than at other times of the oestrous cycle. A higher level of the secretion of the factor may be important for the full development of the priming effect of LH-RF and, consequently, the marked increase in responsiveness of the pituitary gland which occurs during the afternoon of pro-oestrus.
UPTAKE AND METABOLISM IN VIVO OF TRITIATED OESTRADIOL-17β IN TISSUES OF AGEING FEMALE MICE
Authors: GOSDEN R. G. 
Published: December 2008

SUMMARY
The uptake in vivo of tritiated oestradiol-17β has been compared in young and aged ovariectomized CBA/H-T6 mice by examining the levels of radioactivity in tissues 1 h after injection. The specificity of oestradiol uptake was demonstrated by previous treatment of some animals with either diethylstilboestrol or progesterone. The levels of radioactivity in whole tissue extracts were similar in both age groups for the uterus, hypothalamus, cerebrum and serum, but the uptake in the pituitary gland was significantly lower in old mice. There was no evidence of altered hormone metabolism with age.
CIRCADIAN RHYTHM OF CORTICOSTERONE LEVELS IN RAT BRAIN
Authors: BUTTE J. C. , KAKIHANA RYOKO , NOBLE E. P. 
Published: December 2008

SUMMARY
In the present study the circadian changes which occur in the levels of corticosterone in the brain and plasma in Sprague–Dawley rats are reported. The levels of corticosterone in the brain were found to have a daily trough and crest with timing similar to that observed for the plasma steroid. In addition, the effect of histamine stress on the corticosterone content of the particulate and the soluble fractions at the trough and crest was examined. The levels of both brain fractions were significantly higher 20 min after histamine injection. The time of day at which the stress was applied was not a significant factor in the magnitude of the stress response.
BIOCHEMICAL CHANGES IN THE CORPUS LUTEUM OF THE CYCLIC HAMSTER
Authors: CHATTERJEE SUDHA , GREENWALD G. S. 
Published: December 2008

SUMMARY
The corpora lutea (CL) of the hamster secrete progesterone on days 1 and 2 of the oestrous cycle before marked regression at pro-oestrus (day 4) virtually eliminates them from the ovary. Luteal protein and RNA reached their maximum values on day 2 and declined up to day 4. DNA was constant throughout the cycle substantiating the importance of cellular hypertrophy rather than hyperplasia in the growth of the CL. Concentrations of cholesterol and its esters were unchanged between days 1 and 3 but almost doubled in concentration on day 4.
Glucose-6-phosphate dehydrogenase activity was maximal on days 2 and 4, apparently associated on these days with steroidogenesis and lipid metabolism, respectively. A significant increase in acid phosphatase activity occurred on day 3 reaching maximal values on day 4, probably accounting for the rapid regression of the CL. The maximal concentration of 3β-hydroxysteroid dehydrogenase in CL was on day 1, with a gradual decline over the next 3 days.
SOLVOLYSABLE DEOXYCORTICOSTERONE CONJUGATES IN HUMAN URINE
Authors: COPE C. L. , LOIZOU S. 
Published: December 2008

SUMMARY
The nature of the urinary conjugate converted by solvolysis, to free unconjugated deoxycorticosterone (DOC) was studied. A comparison of 11 solvolysis techniques has shown that the method employed in this study yielded 86% of the highest yield by any of the techniques tried. Three successive chromatographic systems on paper showed that no appreciable amounts of contaminants were present in the free DOC eluates, following solvolysis. By preparing authentic [3H]DOC sulphate and subjecting it to solvolysis it was shown that more than 90% of the tritiated DOC was recovered, after chromatography of the free DOC extract. This suggests that much of the solvolysable DOC in human urine is present in the form of the sulphate conjugate.
The levels of DOC, excreted as the solvolysable conjugate in a variety of urine specimens, were shown to be much higher than those of free DOC, the former being 4·8 to 127 times higher than the amount of the latter. This highly variable ratio suggests that the site of production of solvolysable DOC is different from that for free DOC. The only correlation between free and solvolysable DOC was shown in dexamethasone-suppressed patients, in whom the mean percentage remaining after suppression was 30·6% for free DOC, 24·1% for solvolysable DOC and 22·2% for cortisol.
As solvolysable DOC is present in much larger amounts in urine, care is necessary in the storage of urine samples in which free DOC estimates are to be made, as we found that urine specimens left at room temperature for 1 week could show rises of as much as 400% of their starting free DOC levels.
EFFECTS OF SODIUM PENTOBARBITONE ON SERUM GONADOTROPHIN LEVELS AND ON THE INCORPORATION OF 35S FROM METHIONINE INTO PROTEIN IN THE BRAIN AND ANTERIOR PITUITARY DURING THE OESTROUS CYCLE OF THE RAT
Authors: TER HAAR M. B. , MACKINNON P. C. B. 
Published: December 2008

SUMMARY
Ovulation was delayed for 24 h after the administration of sodium pentobarbitone (Nembutal, 35 mg/kg body weight) at 14.00 h, before the critical period on the afternoon of prooestrus. The expected preovulatory surge of serum LH at 18.00 h of pro-oestrus was also delayed until 21.00 h on the following day; however, increased levels (> 12 ng/ml) were observed in 14 out of 23 animals (killed by decapitation) at 21.00 h on the day of Nembutal administration. The serum FSH rise observed on the morning of expected oestrus was extended after Nembutal treatment, and a further rise was noted 24 h later.
Peak levels of incorporation of 35S from methionine into protein of the median eminence area (ME) and of the anterior pituitary (AP) which normally occur about the time of the preovulatory LH surge, were also delayed until 21.00 h on the day following Nembutal administration.
Neither ovulation nor the preovulatory gonadotrophin rises with their accompanying changes in incorporation in the ME and the AP, were altered by Nembutal administered after the pro-oestrous critical period.
Thus Nembutal, while blocking ovulation, inhibits the circadian rhythm of incorporation of 35S from methionine in the brain as well as the peaks of incorporation in the median eminence and the anterior pituitary which accompany the normal preovulatory surges of gonadotrophin.
IMMUNOREACTIVE α- AND β-SUBUNITS OF LUTEINIZING HORMONE IN HUMAN PERIPHERAL BLOOD AND FOLLICULAR FLUID THROUGHOUT THE MENSTRUAL CYCLE, AND THEIR EFFECT ON THE SECRETION RATE OF PROGESTERONE BY HUMAN GRANULOSA CELLS IN TISSUE CULTURE
Authors: HAGEN C. , McNATTY K. P. , McNEILLY A. S. 
Published: December 2008

SUMMARY
The concentration of the common α-subunit of the glycoprotein hormones and of the β-subunit of luteinizing hormone (LHβ) in peripheral blood and follicular fluid was measured throughout the menstrual cycle, and the effects of these subunits, either alone or in combination, on the production of progesterone by human granulosa cells in tissue culture were investigated.
Changes in the serum concentration of α-subunit and immunoreactive `LHβ-like' material throughout the menstrual cycle were similar to those of LH. The concentrations of the subunits before the mid-cycle gonadotrophin peak were not significantly different from those during the luteal phase of the menstrual cycle. Gel filtration of a pooled serum sample obtained at mid-cycle confirmed the presence of immunoreactive α-subunit together with intact LH; however, because of the cross-reactivity of LH in the LHβ assay a distinct peak of LHβ-subunit could not be demonstrated.
In follicular fluid, α-subunit was detectable in large follicles ( ≥ 8 mm) throughout the menstrual cycle at concentrations similar to those found in serum. By contrast α-subunit in small follicles ( < 8 mm) and `LHβ-like' material in all follicles were only detectable during or just after peak concentrations in peripheral plasma.
The LH subunits did not increase the rate of progesterone secretion by human granulosa cells when each was added alone, even at concentrations five times higher than those in plasma. However, when both subunits were added simultaneously there was an increased rate of progesterone secretion comparable to that achieved with intact LH.
It is concluded that the common α-subunit circulates in blood independently of the intact hormones, and that it is present in a proportion of developing Graafian follicles without affecting either the viability or biosynthetic potential of their granulosa cells. During the late follicular phase however, when both the α- and LHβ-like subunits are present in follicular fluid, they may recombine and enhance steroid production by granulosa cells which are undergoing luteinization at this time.
SEASONAL VARIATION IN THE EPISODIC SECRETION OF LUTEINIZING HORMONE AND TESTOSTERONE IN THE RAM
Authors: LINCOLN G. A. 
Published: December 2008

SUMMARY
Rams of an ancient breed of domestic sheep (Soay) were housed under artificial lighting conditions to study the way in which the secretion of LH and testosterone changes in relation to the mating season. Conspicuous changes were found in the short-term fluctuations in plasma LH concentrations related to the cycle of testis growth and regression; serial blood samples collected at short intervals revealed episodic peaks in plasma LH at all times, but there were changes in the frequency (lowest when the testes were regressed and highest when fully active), amplitude (lowest at the peak of testis activity, and highest during the developing phase), and duration of the peaks (shortest when the testes were regressed). In addition, the basal levels changed from being lowest in the regressed phase of the testis cycle, and highest when the gonads were most active.
Plasma testosterone concentrations changed in parallel with the cycle of testis size and were correlated with the fluctuating levels of LH. Each episodic peak in plasma LH was associated with an increase in the level of testosterone, beginning after 0–30 min and rising to a peak at 60–90 min; the speed and magnitude of the response being greatest when the testes were largest, but was not correlated with the magnitude of the LH change.
Injections of LH releasing hormone (5 μg) stimulated an increase in plasma LH and testosterone proportional to the endogenous fluctuations in the hormones at the various stages of the seasonal cycle; LH concentrations were raised to supra-physiological levels after the injections, while testosterone concentrations seldom exceeded the normal peak values at any stage. These observations are used to discuss the role of the hypothalamus in the control of male seasonality with emphasis on the dynamic interplay between the hypothalamus, pituitary and testis.
ANDROSTENEDIONE AND THE CONTROL OF LUTEINIZING HORMONE IN THE EWE DURING ANOESTRUS
Authors: MARTENSZ N. D. , BAIRD D. T. , SCARAMUZZI R. J. , VAN LOOK P. F. A. 
Published: December 2008

SUMMARY
Androstenedione and oestradiol were measured by radioimmunoassay in the utero-ovarian venous plasma of two ewes during anoestrus. The concentrations of both steroids were significantly higher than the corresponding concentrations in peripheral plasma, indicating that androstenedione and oestradiol are secreted by the ovary during anoestrus.
The concentration of LH during anoestrus was measured by radioimmunoassay in jugular venous plasma of control ewes, ewes immunized against 11α-OH-androstenedione–bovine serum albumin and ewes that had been ovariectomized and hysterectomized 9 months previously. During a 12 h sampling period, discharges of LH occurred more frequently in the immunized ewes than in the control group but less frequently than in the ovariectomized group. The frequency of discharge was positively correlated with the titre of androstenedione antibodies in the immunized animals.
After injection of 25 μg oestradiol benzoate (OB) all controls, 3 out of 5 immunized and 4 out of 5 ovariectomized–hysterectomized ewes showed positive feedback. No positive feedback occurred in the two ewes with the highest antibody titres to androstenedione, but negative feedback in response to OB appeared to function normally in all the androstenedione immunized sheep. It is postulated that androstenedione, or one of its metabolites, normally modulates the effects of oestradiol in the control of gonadotrophin secretion in the ewe.
RECOVERY OF PITUITARY SECRETION OF GONADOTROPHINS AND PROLACTIN DURING RE-FEEDING AFTER CHRONIC RESTRICTED FEEDING IN FEMALE RATS
Authors: NAKANISHI YOSHIHIKO , MORI JUNICHI , NAGASAWA HIROSHI 
Published: December 2008

SUMMARY
The effects on reproductive function of restriction to one half of the normal food intake for 30 or 60 days and subsequent unrestricted feeding were investigated in adult female Sprague–Dawley rats.
Restricted feeding resulted in the cessation of oestrous cycles within 9 to 28 days, associated with decreased pituitary, ovarian and uterine weights. Pituitary content and concentration of FSH were increased by restricted feeding and the levels of FSH in 60 day underfed rats were about twice as high as those of the controls at dioestrus. There was little difference in pituitary LH content between the underfed groups and the controls at the end of restricted feeding. Pituitary LH concentration was significantly higher in rats underfed for 60 days than in the control rats. Pituitary prolactin content was one half and one third of that in control rats in rats underfed for 30 and 60 days respectively. Pituitary prolactin concentration was also decreased by restricted feeding. At the end of restricted feeding, no differences in serum LH and prolactin levels were found between the groups, whereas the serum FSH level in 60 day underfed rats was higher than that in the controls at dioestrus.
After re-feeding, normal oestrous cycles returned within 3–5 days in almost all rats, regardless of the length of the previous cessation of oestrous cycles. Pituitary contents of FSH and LH in underfed rats decreased after re-feeding following the return of oestrous cycles. The rate of decrease was much greater in 60 day underfed rats than that in 30 day underfed rats. On the other hand, serum levels of FSH, LH and prolactin in these underfed rats were increased by re-feeding and the levels in the evening of the first pro-oestrus were higher than those in the morning of dioestrus and pro-oestrus. Serum levels of these hormones increased more in 60 day underfed rats than in the other groups at any stage. After re-feeding, pituitary, ovarian and uterine weights increased and the uterine epithelial layer was clearly repaired in both underfed groups, although not always to the control levels by the first oestrus. The end-bud system of the mammary gland which degenerated during restricted feeding was comparable to that of the controls at the first oestrus after re-feeding in 30 day underfed rats, but not in 60 day underfed rats.
INHIBITORY EFFECT OF PROSTAGLANDIN F2α ON OXYTOCIN RELEASE AND ON MILK EJECTION IN LACTATING RATS
Authors: PRILUSKY J. , DEIS R. P. 
Published: December 2008

SUMMARY
The effect of prostaglandin F2α (PGF2α) on milk ejection and on oxytocin release during suckling for one or two periods of 30 min was studied in lactating rats. Doses of PGF2α (20 or 40 μg) were injected i.p. 15 min before the suckling period. Control rats were injected with physiological saline. An inhibition of milk ejection proportional to the dose of drug administered was obtained. A normal milk ejection response was induced with a small dose of oxytocin injected immediately before nursing to mothers treated with PGF2α, indicating that the blocking effect was not due to a lack of mammary gland response. Two groups of mothers were injected with 40 μg PGF2α 2 and 4 h respectively before suckling. In both groups milk ejection was partially but significantly inhibited. In rats pre-treated with sodium pentobarbitone (3·5 mg/100 g body wt) to prevent the release of oxytocin induced by suckling, PGF2α (10 or 20 μg) did not modify the inhibition of milk ejection indicating that PGF2α does not have milk-ejecting activity. The administration of oxytocin to anaesthetized rats, immediately before a second suckling period, induced a normal milk-ejection response while in the rats treated with PGF2α, oxytocin was less effective. The results indicate that PGF2α inhibited milk ejection by a central block on oxytocin release and that the lipid is not able to mimic peripherally the milk-ejecting activity of oxytocin.
CHANGES IN THE WEIGHT OF THE ADRENAL GLANDS AND IN THE CONCENTRATION OF PLASMA CORTICOSTERONE IN PERINATAL RATS AFTER PRENATAL TREATMENT WITH OESTRADIOL BENZOATE
Authors: EGUCHI Y. , ARISHIMA K. , MORIKAWA Y. , HASHIMOTO Y. 
Published: December 2008

SUMMARY
On day 20 of gestation, foetal rats received a subcutaneous injection of 0·01 mg oestradiol benzoate dissolved in 0·05 ml sesame oil; foetuses in other litters were given sesame oil alone. Autopsy was performed on day 22 of gestation, at delivery or at various times after birth. Gravimetric and histological observations of the adrenals from oestradiol-treated, oil-treated and intact litter-mate control foetal and neonatal rats were performed together with determination of plasma corticosterone concentrations. Activity of 3β-ol dehydrogenase was also examined histochemically in the adrenals from these animals.
The results indicated that oestradiol benzoate when given prenatally prevented the neonatal decline of adrenal weight and adrenocortical cell size. In normal or oil-treated rats, plasma corticosterone concentration was greatly increased during delivery and 2 h after birth, declining up to 12 h after birth. Oestradiol benzoate prevented this perinatal increase and suppressed the activity of 3β-ol dehydrogenase in the perinatal adrenal cortices.