bluuebunny/crossref_metadata_2025_split huggingface dataset:
OESTROGENS AND PROLACTIN AS POSSIBLE REGULATORS OF PUBERTY
Authors: WUTTKE W. , DÖHLER K. D. , GELATO M. 
Published: December 2008

SUMMARY
At day 15 after birth, high serum oestradiol levels, high FSH levels and occasionally high LH levels were observed in control female rats. Injections of potent and specific antisera for oestrogen between days 8–15 prevented LH peaks and decreased basal LH levels. Serum FSH levels were increased after treatment. High oestradiol levels at this time appear to exert a positive feedback action on phasic as well as tonic LH release.
Injections of ovine prolactin (0·5 μg/g body wt twice daily) between days 8–25 of life significantly advanced the day of vaginal opening in immature rats and initiated regular oestrous cycles. Such treatment completely prevented high LH levels at day 15 but serum FSH levels remained high. Prolactin and progesterone levels were higher at day 25 than at day 15 in control rats and at that time LH and FSH levels were low. Prolactin treatment had a depressant effect on endogenous prolactin and progesterone levels. It is proposed that after day 20 the positive feedback threshold of oestradiol on LH release is at a mature, highly sensitive level. The steady increment in serum prolactin and/or progesterone levels between day 20 and puberty, however, inhibited phasic LH release thus preventing early puberty. The possible mechanisms of action of prolactin are discussed.
PRODUCTION OF PROSTAGLANDINS E AND Fα BY CORPORA LUTEA, CORPORA ALBICANTES AND STROMA FROM THE HUMAN OVARY
Authors: CHALLIS J. R. G. , CALDER A. A. , DILLEY SUSAN , FORSTER CHRISTINE S. , HILLIER K. , HUNTER D. J. S. , MACKENZIE I. Z. , THORBURN G. D. 
Published: December 2008

SUMMARY
This study has shown that corpora lutea, stromal tissue and corpora albicantes from human ovaries contain prostaglandin E (PGE) and PGFα, and that the two former tissues can synthesize these prostaglandins during incubation. Enhanced synthesis, especially of PGE, occurred on adding arachidonic acid to the incubation medium, and the presence of prostaglandin synthetase activity was conclusively demonstrated.
In corpora lutea obtained during the early and mid-luteal phase, the mean concentrations of PGE and PGFα were 34·3 and 9·6 ng/g respectively (mean ratio PGE:PGFα = 3·7); similar values were found in three corpora lutea from women at 10–12 weeks of pregnancy. All these corpora lutea contained appreciable amounts of progesterone and oestradiol-17β. Prostaglandin levels were generally lower in corpora lutea obtained during the late luteal phase, although the PGE:PGFα ratio had increased to a mean value of 8·4. In corpora albicantes, the concentrations of both PGE and PGFα were significantly higher than the levels found in corpora lutea (P < 0·01), whilst the mean ratio of PGE:PGFα had fallen significantly to 1·8 (P < 0·01). Prostaglandin levels in stromal tissue varied considerably between individuals. The mean values were significantly lower than those of the corpora albicantes (P < 0·01) but not significantly different to corpora lutea at any stage.
These findings are discussed in relation to the possible role of prostaglandins in ovarian steroidogenesis and corpus luteum regression in man.
LUTEINIZING HORMONE AND LUTEINIZING HORMONE RELEASING HORMONE-LIKE IMMUNOREACTIVITY IN THE JUGULAR VENOUS BLOOD OF SHEEP AT VARIOUS STAGES OF THE OESTROUS CYCLE
Authors: FOSTER J. P. , JEFFCOATE S. L. , CRIGHTON D. B. , HOLLAND D. T. 
Published: December 2008

SUMMARY
Luteinizing hormone and LH-RH-like immunoreactivity were measured in the jugular venous plasma of Clun Forest ewes at various stages of the oestrous cycle.
Blood samples were collected through jugular venous cannulae every 2 h for at least 20 days from three ewes during the breeding season. The ewes were checked twice daily for oestrus using a vasectomized ram. Plasma LH peaks of apparent height 112–192 ng NIH-LH-S17 equivalents/ml were detected at oestrus with basal levels of 2–15 ng/ml during most of the remainder of the 17-day oestrous cycle. Peaks of LH-RH-like immunoreactivity occurred at various times of the cycle. The apparent maximal level of these peaks was 220 pg/ml compared with basal levels of < 10 pg/ml. Further ewes (two for each group) were sampled at 4 min intervals for 12 h, (1) from onset of oestrus, (2) 36–48 h after onset of oestrus or (3) on day 10 of the oestrous cycle. In the ewes sampled at oestrus, peaks of LH-RH-like immunoreactivity were detected before, during and after the preovulatory LH peak. Those detected after the LH peak were unassociated with any further increases in the plasma LH level. In the ewes sampled 36–48 h after onset of oestrus and on day 10 of the cycle, several peaks of LH-RH-like immunoreactivity unassociated with any increases in the LH level were detected. These peaks, and those detected at oestrus, had durations of only one or two samples, and in some cases reached levels of several ng/ml compared with basal levels of < 10 pg/ml. The significance of these results is discussed.
ALPHA-ADRENERGIC RECEPTOR ACTIVITY, CYCLIC AMP AND LIPOLYSIS IN ADIPOSE TISSUE OF HYPOTHYROID MAN AND RAT
Authors: RECKLESS J. P. D. , GILBERT C. H. , GALTON D. J. 
Published: December 2008

SUMMARY
Lipolysis and intracellular levels of cyclic AMP of adipose tissue from man and rat in both hypothyroid and euthyroid states were studied in response to stimulation by catecholamines in vitro. Hypothyroid patients were studied before and after treatment, and were also compared with euthyroid obese controls. The experimental group of rats was rendered hypothyroid by the addition of 2·9 mm-propylthiouracil to their drinking water, and their status confirmed by plasma thyroid function tests.
Evidence for α-adrenergic receptor activity was found in rat adipose tissue, but was less marked than the pronounced α-adrenergic activity in human adipose tissue. Glycerol release from adipose tissue in response to noradrenaline stimulation was less marked in hypothyroidism in both species, and was related to an increased α-adrenergic activity.
No evidence was found for increased α-adrenergic effects on cyclic AMP level in hypothyroid subjects, and little evidence was found in adipose tissue from hypothyroid rats. This discrepancy may be due to the presence of the phosphodiesterase inhibitor, theophylline, in the incubation system. The possible modulatory role of thyroid hormones on receptor and phosphodiesterase activity, and on lipolysis, is discussed.
A COMPARISON OF THE EFFECTS OF NEONATALLY ADMINISTERED TESTOSTERONE, TESTOSTERONE PROPIONATE AND DIHYDROTESTOSTERONE ON AGGRESSIVE AND SEXUAL BEHAVIOUR IN THE FEMALE GOLDEN HAMSTER
Authors: PAYNE A. P. 
Published: December 2008

SUMMARY
Female golden hamsters received one of the following treatments on the day following birth: (i) 300 μg testosterone propionate in arachis oil, (ii) 300 μg testosterone in oil, (iii) 300 μg dihydrotestosterone in oil, or (iv) oil alone. As adults all animals underwent three tests for behaviour. First, while intact, females were observed in aggressive interactions with males. Secondly, after ovariectomy, females were primed with oestrogen + progesterone and tested for receptivity with a stud male. Thirdly, all ovariectomized females were primed with testosterone propionate and tested for male patterns of behaviour with a receptive female.
Compared with the effects of oil administration (control), testosterone propionate administration resulted in increased aggressiveness and the capacity to show male patterns of sexual behaviour, together with a decreased capacity to show female patterns of sexual behaviour. Testosterone increased aggression and male sexual behaviour, but had no effects on receptivity, while dihydrotestosterone decreased some components of receptivity but had no effects on aggressiveness or the capacity to show male mating behaviour.
EFFECTS OF PINEALECTOMY ON THE RAT OESTROUS CYCLE AND PITUITARY GONADOTROPHIN RELEASE
Authors: BLAKE C. A. 
Published: December 2008

SUMMARY
In 4-day cyclic rats kept in a room with the lights on from 05.00 to 19.00 h, sham pinealectomy or pinealectomy on the morning of pro-oestrus did not alter the length of the oestrous cycle for 44 days or the time and magnitude of the rises in LH, FSH and prolactin in the circulation in the afternoon on pro-oestrous days 0, 20 or 44. On day 45, the light schedule was set forward 4 h to run from 09.00 to 23.00 h. The rats continued to have seven additional consecutive 4-day oestrous cycles. On day 27 after the resetting of the light schedule, the pro-oestrous rises in serum LH, FSH and prolactin were delayed 4 h in all rats and a normal quota of eggs was ovulated that night. Other 4- and 5-day cyclic rats which had been made persistently oestrous by anterior deafferentation of the medial basal hypothalamus (AC) underwent pinealectomy. These AC-pinealectomized rats were ovariectomized 60 days later and histological examination of the ovaries revealed no evidence of recent ovulation. Five to six weeks after ovariectomy, sequential blood samples were withdrawn through indwelling atrial cannulas in the AC-pinealectomized-ovariectomized rats and in ovariectomized, pinealectomized-ovariectomized and AC-ovariectomized rats. Regular pulsatile rhythms in plasma LH were measured in all rats. Subcutaneous injection of 50 μg oestradiol benzoate in oil lowered plasma LH levels in all four groups but caused an LH surge in the afternoon 2 days later only in the ovariectomized and pinealectomized-ovariectomized rats. The results indicate that the pineal gland in rats kept on a 14 h light: 10 h darkness schedule does not play an active or permissive role in the timing or magnitude of LH, FSH or prolactin release at pro-oestrus, the length of the oestrous cycle, or LH release in ovariectomized rats.
EFFECTS OF SUB-TOTAL GASTRO-INTESTINAL PANCREATECTOMY OF THE RAT FOETUS
Authors: FÉLIX J. M. , JACQUOT R. L. 
Published: December 2008

SUMMARY
Sub-total pancreatectomy in utero was performed in 18-day-old rat foetuses. Pancreatectomized, sham-operated and control foetuses were collected 3 days later and body weight, glucose and insulin levels in blood, and glycogen content and glucose-6-phosphatase (G-6-Pase) activity of the liver were determined. Pancreatectomized foetuses showed only very small pancreatic remnants (≤ 1 mg) and accordingly their insulin levels were much lower (four to five times) than those of sham-operated or control foetuses; their blood glucose levels were slightly increased and liver glycogen content and G-6-Pase activity were slightly reduced; their body weights were also reduced.
These results are discussed in relation to other relevant data in the literature. They afford direct experimental evidence of the endogenous origin of insulin in the foetal blood. It is suggested that during the last days of intra-uterine life insulin merely completes the action of the glucocorticoids on glycogen storage in rat foetal liver and probably contributes to foetal body growth. Its relative ineffectiveness on the foetal blood glucose level is not explained. As pancreatectomized foetuses develop sub-normal liver G-6-Pase activity, glucagon is probably not responsible for the increase in this activity occurring during normal development before birth.
PLASMA FOLLICLE-STIMULATING HORMONE DURING PHOTOPERIODICALLY INDUCED SEXUAL MATURATION IN MALE JAPANESE QUAIL
Authors: FOLLETT B. K. 
Published: December 2008

SUMMARY
Follicle-stimulating hormone (FSH) was measured in Japanese quail using a heterologous radioimmunoassay, the specificity of which was confirmed by its cross-reactions with purified chicken FSH and luteinizing hormone (LH).
Plasma concentrations of FSH, LH and testosterone were determined in quail during the testicular growth and sexual maturation which follows their transfer from short to long daylengths. All three hormones could be detected in short-day birds but their concentrations were greatly increased following photostimulation. Plasma FSH increased 12-fold during the first 9 long days, remained at this level for a week, and then declined steadily so that by the time the birds were sexually mature the level of FSH had decreased to one-third of the maximum level. LH reached a high level (five times the short day level) after 4 long days. Thereafter two patterns of LH secretion could be distinguished. In one experiment the high level of LH was maintained unchanged throughout sexual maturation while in another experiment LH secretion decreased significantly between days 11 and 28 of photostimulation.
A strong correlation existed between testicular growth and the plasma FSH concentration. It was maximal during the phase of rapid testicular growth and decreased as spermiogenesis began.
The pituitary FSH content increased during photostimulation. Castration caused a 20-fold rise in plasma FSH compared with that in intact quail. The change in LH concentration after castration was about eightfold.
The changes in hormone secretion were strikingly similar to those found during sexual development and puberty in the rat.
PURIFICATION OF CANINE PROLACTIN BY PREPARATIVE ISOTACHOPHORESIS
Authors: KNIGHT P. J. , GRONOW M. , HAMILTON J. M. 
Published: December 2008

SUMMARY
Preparative isotachophoresis in polyacrylamide gel using carrier ampholytes as 'spacers' has been used to purify prolactin from canine pituitary extracts. Using Ampholine pH 5–8 as spacers, a prolactin fraction was obtained which was essentially homogeneous as judged by the criteria of disc electrophoresis and isoelectric focusing. Amino acid analysis indicated a close similarity between canine and ovine prolactin. A growth hormone fraction, identified by its electrophoretic mobility, was also obtained although this was heterogeneous in disc electrophoresis at alkaline pH.
OVINE PLACENTAL LACTOGEN: ACUTE EFFECTS ON INTERMEDIARY METABOLISM IN PREGNANT AND NON-PREGNANT SHEEP
Authors: HANDWERGER STUART , FELLOWS R. E. , CRENSHAW M. C. , HURLEY THOMAS , BARRETT JANET , MAURER W. F. 
Published: December 2008

SUMMARY
The intravenous administration of ovine placental lactogen to pregnant and non-pregnant sheep produced significant acute decreases in plasma free fatty acid, glucose and amino nitrogen concentrations. Plasma insulin concentrations decreased 1 h after administration of ovine placental lactogen and then increased significantly above baseline concentrations. The results suggest that, like human placental lactogen, ovine placental lactogen is important in the modulation of intermediary metabolism during pregnancy. The sheep is an excellent animal model for the investigation of the physiology of placental lactogen.
THE PITUITARY RESPONSE TO EXOGENOUS LUTEINIZING HORMONE RELEASING FACTOR IN STEROID-TREATED GONADECTOMIZED RATS
Authors: AIYER M. S. , SOOD M. C. , BROWN-GRANT K. 
Published: December 2008

SUMMARY
Rats gonadectomized 1–2 months previously were anaesthetized with sodium pentobarbitone and 50 ng/100 g body weight of a synthetic decapeptide gonadotrophin releasing factor (LH-RF) injected intravenously. Plasma concentrations of LH and FSH were determined by radioimmunoassay in samples taken before and at intervals up to 60 min after the injection of LH-RF. The pituitary response was evaluated by determining the maximal increment in plasma gonadotrophin concentrations and by estimating the area under the plasma gonadotrophin concentration curves.
In both males and females the pituitary response was increased in animals given 20 μg oestradiol benzoate 3 days earlier. Progesterone (2·5 mg) had no effect on the response measured 4 h later in oil-treated rats, male or female. In oestrogen-primed rats progesterone administration produced a significantly increased response in females that was not seen if sodium pentobarbitone was given at the time of progesterone injection. In oestrogen-primed males progesterone produced some increase in sensitivity but less than was seen in females. Both in males and in females that had received androgen on day 4 of postnatal life sodium, pentobarbitone had no effect on the responses of oestrogen plus progesterone-treated rats to LH-RF. When two injections of LH-RF were given 60 min apart, the second response was greater than the first in animals, both male and female, that had been primed with oestrogen. The second response was no greater than the first in oil-treated females.
The results suggest that oestrogen can increase pituitary sensitivity to LH-RF in both male and female rats and that LH-RF itself can increase pituitary sensitivity to a second injection of LH-RF in both male and female rats if they have received oestrogen. It is suggested that the differences between the pituitary responses of females and males after oestrogen plus progesterone treatment and the major differences in gonadotrophin secretion reported previously (Brown-Grant, 1974) may be accounted for on the basis of there being a relatively slight increase in endogenous LH-RF secretion with a consequent marked rise in pituitary responsiveness in female but not in male rats.
ENDOCRINE CHANGES ASSOCIATED WITH LUTEAL REGRESSION IN THE EWE; THE SECRETION OF OVARIAN OESTRADIOL, PROGESTERONE AND ANDROSTENEDIONE AND UTERINE PROSTAGLANDIN F2α THROUGHOUT THE OESTROUS CYCLE
Authors: BAIRD D. T. , LAND R. B. , SCARAMUZZI R. J. , WHEELER A. G. 
Published: December 2008

SUMMARY
The concentrations of oestradiol, androstenedione, progesterone and prostaglandin F2α (PGF2α) were measured in utero-ovarian venous blood collected throughout six oestrous cycles in two ewes with utero-ovarian autotransplants. The secretion of oestradiol was closely correlated with that of androstenedione (r = 0·67, P < 0·001) indicating a common origin from the Graafian follicle. The concentration of these two steroids fluctuated at random throughout the luteal phase with the maximum secretion occurring about 2 days before the onset of oestrus. Functional regression of the corpus luteum, as indicated by a fall in the secretion of progesterone, began on day 12 or day 13, i.e. about 4 days before the onset of oestrus. In five of the six cycles the first significant rise in the secretion of PGF2α occurred on days 12–14 at the time of decline of progesterone secretion, although the release of PGF2α was maximal on the day before the onset of oestrus. There was very little release of PGF2α from the uterus before day 12. The temporal relationship of these events suggests that the uterus will only release PGF2α after it has been primed for 7–10 days with progesterone. The initiation of luteal regression is independent of secretion of oestradiol by the pre-ovulatory follicle which may, however, stimulate the further release of PGF2α responsible for irreversible structural luteolysis on the day of pro-oestrus.
PITUITARY AND PLASMA LEVELS OF GONADOTROPHINS IN FOETAL AND NEWBORN MALE AND FEMALE RATS
Authors: CHOWDHURY MRIDULA , STEINBERGER E. 
Published: December 2008

SUMMARY
Levels of LH and FSH were measured by radioimmunoassay in serum, pituitary and placental tissues of male and female foetal and newborn rats. No gonadotrophins were detected in placental tissues or amniotic fluid. In the male, pituitary FSH and LH were first detected on day 17 of gestation. Gonadotrophins could not be detected in any female tissues until birth. In male foetuses the highest levels of both LH and FSH in the circulation were found on day 16 of foetal life; subsequently the levels decreased dramatically.
INCORPORATION OF RAT PROLACTIN INTO RAT MILK IN VIVO AND IN VITRO
Authors: GROSVENOR C. E. , WHITWORTH N. S. 
Published: December 2008

SUMMARY
Rat prolactin (11 i.u./mg) was continuously infused into the circulation of urethaneanaesthetized lactating rats for 35 min at doses of either 200 or 472 ng/min. The immunoreactive prolactin in both milk and plasma rose quickly during the first 20–25 min of infusion, then stabilized at similar levels over baseline (68 and 98 ng/ml for milk and plasma, respectively, with the 200 ng/min dose and 250 and 230 ng/ml, respectively, with the 472 ng/min dose). The concentration of prolactin in plasma fell after the infusion was stopped, whereas that in the milk either did not fall at all or fell slightly to a new stabilized level. There was a rapid and extensive loss in the immunoreactivity of prolactin added to milk when rat milk was incubated in vitro (37 °C for 1–120 min) with either 600 ng/ml of extracted pituitary prolactin (NIAMDD RP-1) or unit equivalent amounts of prolactin obtained from pituitary culture media (secreted prolactin, supplied by C. S. Nicoll). Significantly greater amounts of added RP-1 prolactin were lost when it was incubated with milk obtained after 4 h than after 18 h of non-suckling. There was, however, no drop in endogenous immunoreactive milk prolactin levels (350–400 ng/ml) when rat milk was incubated with saline for 30 min. This suggests that milk prolactin obtained as a result of plasma transfer is different chemically from the milk prolactin resulting from the addition of either RP-1 or secreted prolactin to milk in vitro.
Approximately 90% of 131I-labelled rat prolactin appeared in the trichloroacetic acid precipitable fraction after incubation (37 °C for 120 min) with milk obtained after 4 h of non-suckling in either the presence or absence of thiouracil (added to prevent binding of 131I or 131I-labelled fragments to milk protein). The recovery was slightly less when 131I-labelled prolactin was incubated with milk obtained after 18 h of non-suckling.
These data suggest that prolactin is quickly transferred from plasma into milk in direct relation to the plasma concentration. Once there, much of it appears to be retained by the milk perhaps chemically or physically bound; there is little, if any, degradation of the hormone. We conclude that the lactating rat mammary gland may function normally as an excretory organ for prolactin.
PROLACTIN, DIURETICS AND URINARY ELECTROLYTES IN NORMAL SUBJECTS
Authors: AUTY R. , BRANCH R. A. , COLE E. N. , LEVINE D. , RAMSAY L. 
Published: December 2008

SUMMARY
The relationship of plasma prolactin concentration and renal electrolyte excretion has been investigated in six normal male volunteers. In two studies, 80 mg frusemide were administered at 18.00 h on Day 1 and followed by dietary sodium restriction. In study A, after 38 h of sodium depletion, a second dose of frusemide was administered at 08.00 h on Day 3. In study B, after 14 h of sodium depletion, the effect of administration of 100 mg spironolactone or 45 mg prorenoate potassium (another aldosterone antagonist) at 08.00 h on Day 2 was compared with that of a placebo.
After the first dose of frusemide in study A, the mean plasma prolactin concentration correlated negatively with the urinary Na and K excretion over 5 h. After 38 h sodium depletion, the plasma prolactin concentration correlated positively with urinary Na excretion following the second dose of frusemide. In study B, after Na depletion for 14 h the plasma prolactin concentration at 08.00 h on Day 2 had a positive correlation with the 24 h urinary log10 Na:K ratio following placebo administration and had negative correlations with the true urinary log10 Na:K ratio following spironolactone and prorenoate potassium administration.
Neither acute Na deprivation nor the administration of single doses of frusemide, spironolactone or prorenoate potassium appeared to affect the normal circadian rhythm of plasma prolactin concentrations which remained constant for each subject throughout the 3 months covered by the investigation.
The correlations of plasma prolactin concentration to renal excretion of electrolytes, with no evidence for a negative feedback control mechanism, suggest an indirect relationship between prolactin and renal function.