bluuebunny/crossref_metadata_2025_split huggingface dataset:
HYPOTHALAMIC, PITUITARY AND TESTICULAR FUNCTION DURING SEXUAL MATURATION OF THE MALE RAT
Authors: PAYNE A. H. , KELCH R. P. , MURONO E. P. , KERLAN J. T. 
Published: December 2008

SUMMARY
Hypothalamic content of gonadotrophin-releasing hormone (GnRH), serum LH and FSH, capacity of the testis to synthesize testosterone in vitro, and testicular 5-ene-3β-hydroxysteroid dehydrogenase-isomerase and 17β-hydroxysteroid dehydrogenase were measured in groups of rats at approximately 5 day intervals from birth to day 64 and at days 74 and 89. The capacity of the testes to synthesize testosterone in vitro was measured in the presence of a saturating dose of rat LH. Gonadotrophin-releasing hormone increased steadily from 0·17 ng per hypothalamus at birth to a maximum of 7 ng at day 52 and then remained constant. LH concentrations were highly variable and often exceeded adult values between days 10 and 32. After day 32 a steady rise was observed which reached adult values between days 37 and 42. FSH concentrations markedly increased from 255 ng/ml observed at birth and day 10 to a peak value of 1000 ng/ml at day 32. Subsequently there was a steady decline in FSH values until day 74 when the concentration returned to values found at birth. 5-ene-3β-Hydroxysteroid dehydrogenase-isomerase activity exhibited a rapid increase between days 12 and 19 followed by an even greater rate of increase between days 19 and 32 when adult levels were attained. 17β-Hydroxysteroid dehydrogenase activity was very low between birth and day 22. Enzyme activity began to increase at day 22 with a rapid increase in activity observed between days 37 and 58. The increase in capacity to synthesize testosterone closely followed the increase in 17β-hydroxysteroid dehydrogenase activity. The study demonstrates that during sexual maturation in the male rat, changes in serum LH and FSH do not reflect changes in hypothalamic GnRH. The appearance of Leydig cells as monitored by 5-ene-3β-hydroxysteroid dehydrogenase-isomerase activity precedes by approximately 20 days the increase in testicular capacity to synthesize testosterone in vitro. The latter coincides with the increase in 17β-hydroxysteroid dehydrogenase activity. These results suggest that 17β-hydroxysteroid dehydrogenase is a limiting factor in the ability of the testis to respond to LH stimulation.
OVARIAN VENOUS BLOOD FLOW IN NON-PREGNANT AND PREGNANT RATS
Authors: BRUCE N. W. , DIMMITT S. B. 
Published: December 2008

SUMMARY
A modified venous outflow technique was used to measure ovarian blood flow in the rat. The rate of flow through the right ovary was 0·198 ± 0·009 (s.e.m.), 0·476 ± 0·076 and 0·958 ± 0·162 ml/min in six Day 0 (dioestrous), five Day 16 and six Day 22 pregnant rats respectively. The intravenous administration of 50 i.u. human chorionic gonadotrophin increased ovarian blood flow by 26 ± 4, 57 ± 19 and 46 ± 9% respectively, from 2 to 8 min after the injection. The present ovarian venous outflow results are substantially higher than those previously reported in the rat but agree with values determined with radioactive microspheres.
ENZYMIC CHANGES IN THE CERVIX OF THE RAT AND HAMSTER DURING THE OESTROUS CYCLE AND THE EFFECT OF STEROIDS
Authors: ZACHARIAH ELIZABETH , MOUDGAL N. R. 
Published: December 2008

SUMMARY
Changes in four hydrolytic enzymes, namely acid phosphatase, alkaline phosphatase, arylsulphatase A and B, of the cervix of the rat and hamster have been studied during the 4-day oestrous cycle. All four enzymes showed maximal activity on the day of oestrus and least activity on day 2 of dioestrus. All the enzymes showed significant reduction of activity after ovariectomy, arylsulphatase A and B showing the earliest changes in specific activity.
A single subcutaneous injection of 0·02 μg oestradiol-17β/rat increased the specific activity of arylsulphatase A and B from the low ovariectomized level to that observed in control oestrous animals within 18 and 6 h respectively. A higher concentration of oestradiol-17β (2·0 μg) had an inhibitory effect. Progesterone was without effect on arylsulphatase B activity, but when given (2·0 mg) with 0·02 μg oestradiol-17β, it inhibited the response to oestrogen.
Cycloheximide prevented the rise in arylsulphatase B activity occurring after oestrogen injection, suggesting a regulation of cervical arylsulphatase B at the level of protein biosynthesis. These results suggest that arylsulphatase B activity may be induced by oestrogen in the cervix of the rat.
STEROIDOGENESIS IN HUMAN FOLLICLES APPROACHING OVULATION AS JUDGED FROM ASSAYS OF FOLLICULAR FLUID
Authors: FOWLER R. E. , CHAN S. T. H. , WALTERS D. E. , EDWARDS R. G. , STEPTOE P. C. 
Published: December 2008

SUMMARY
Human chorionic gonadotrophin (HCG) was given to patients at mid-cycle before the endogenous LH surge. Graafian follicles were aspirated 32–33 h later, before ovulation was expected, and the levels of several steroids in follicular fluid and in matching serum samples were measured by radioimmunoassay. Two types of Graafian follicle were identified at laparoscopy, based on the nature of the oocyte, granulosa cells and follicular fluid withdrawn from the follicles. Some were large, preovulatory and presumably becoming luteinized while others were generally smaller, non-ovulatory and still growing.
The concentrations of dehydroepiandrosterone (DHEA) and 17α-hydroxypregnenolone (Δ5 intermediates), androstenedione and testosterone were higher in non-ovulatory follicles, whereas large follicles usually contained high levels of progesterone, 17α-hydroxyprogesterone, pregnenolone and oestradiol-17β. A cluster analysis of these data grouped follicles into two distinct clusters, which accorded with their identification as ovulatory or non-ovulatory at laparoscopy.
Levels of progesterone, 17α-hydroxyprogesterone and oestradiol-17β in follicular fluid were high in preovulatory follicles in comparison with plasma. Results in two patients indicated that plasma levels of these steroids were determined by the preovulatory follicle. Levels of plasma Δ5 steroids were closer to follicular fluid concentrations, whereas DHEA was higher in plasma.
The role of the theca and granulosa is discussed in relation to the synthesis of progesterone and oestradiol-17β in follicles as ovulation approaches.
MECHANISM OF INCREASED PROLACTIN SECRETION BY SULPIRIDE
Authors: MACLEOD R. M. , ROBYN CLAUDE 
Published: December 2008

SUMMARY
The effect of sulpiride, a neuroleptic agent, on the secretion of prolactin by the anterior pituitary gland of the rat was studied. A significant increase in serum prolactin was observed after subcutaneous administration of the drug. Although sulpiride (0·10μmol/l or 0·14 mmol/l) had no effect on the secretion of newly synthesized or radioimmunoassayable prolactin in vitro, the drug significantly overcame the inhibitory action that dopamine (0·50 μmol/l) exerted on prolactin secretion. Rats implanted with a prolactin-secreting pituitary tumour MtTW15 showed an inhibition of prolactin biosynthesis and release. Injection of these rats with sulpiride restored prolactin biosynthesis and release of the hormone toward normal levels. These results demonstrate that sulpiride has a direct effect on the pituitary antagonizing the inhibitory effects exerted by dopaminergic mechanisms, although the drug itself does not stimulate the secretion of prolactin in vitro. Sulpiride may have a direct action on the pituitary lactotrophs in vivo, but effects at higher centres have not been excluded.
DEVELOPMENTAL CHANGES IN THE RESPONSES OF THE ADRENAL GLANDS OF FOETAL SHEEP TO ENDOGENOUS ADRENOCORTICOTROPHIN, AS INDICATED BY HORMONE RESPONSES TO HYPOXAEMIA
Authors: JONES C. T. , BODDY K. , ROBINSON J. S. , RATCLIFFE J. G. 
Published: December 2008

SUMMARY
The change in plasma ACTH and corticosteroid concentrations in response to a 60 min period of hypoxaemia were studied in foetal and adult sheep during the latter half of pregnancy. Hypoxaemia consistently caused large rises in the concentration of ACTH in foetal plasma, the magnitude of which did not change with gestational age but was related to the physiological state of the foetus. Before 139 days small and slow rises in corticosteroid (predominantly cortisol) concentration in foetal plasma were observed during hypoxaemia, and these may have been of maternal origin. After 139 days, hypoxaemia caused a rapid and large rise in the concentration of cortisol and corticosterone in foetal plasma, which was largely of foetal origin. Hypoxaemia caused no consistent change in maternal plasma ACTH concentration but was associated with progressive increases in plasma cortisol concentrations. The cortisol:corticosterone ratio in foetal plasma was 1·5 before 139 days and increased to 4·1 several days before term which was lower than the value of 9 in maternal plasma. Small concentrations of 11-deoxycortisol and cortisone were detected in maternal and foetal plasma, the changes of which were small during hypoxaemia.
The results indicate that a maturational change in the sensitivity of the foetal adrenal to endogenous ACTH occurs several days before term.
EFFECT OF METHALLIBURE ON GONADOTROPHIC CONTENT, OVARIAN 32P UPTAKE AND GONADOSOMATIC INDEX IN THE FRESHWATER CATFISH, HETEROPNEUSTES FOSSILIS (BLOCH)
Authors: SINGH T. P. , RAIZADA R. B. , SINGH AJAY KUMAR 
Published: December 2008

SUMMARY
Gonadotrophin content in the pituitary gland and blood serum as well as ovarian 32P uptake were studied in response to methallibure treatment in H. fossilis. There was a marked reduction in the gonadotrophic activity of the pituitary gland and blood serum within 3 weeks of methallibure treatment (100 μg/g). A simultaneous significant reduction was also recorded in the ovarian activity of these fish. The fall in ovarian activity caused by methallibure could not be prevented by the administration of LH, FSH or LH + FSH. After cessation of methallibure treatment, LH + FSH (50 μg each) administration restored ovarian activity. It is evident from these results that methallibure alters the secretion of gonadotrophin, and also prevents its action on the ovary.
CONTROL OF ADRENOCORTICOTROPHIN SECRETION BY CATECHOLAMINES IN THE PREGNANT AND FOETAL SHEEP
Authors: JONES C. T. , ROBINSON R. O. , LUTHER E. , RITCHIE J. W. K. , WORTHINGTON D. 
Published: December 2008

SUMMARY
The effect of adrenaline on the maternal and foetal plasma ACTH concentration of twelve pregnant sheep with chronically implanted vascular catheters has been studied. Adrenaline infused into the jugular vein of the ewe or foetus produced carotid arterial adrenaline concentrations of 1–9 ng/ml. The foetal plasma ACTH was 253 ± 73 pg/ml and it showed a fivefold increase during adrenaline infusion; the ACTH concentration achieved was proportional to the plasma adrenaline. In the ewes plasma ACTH was 99 ± 23 pg/ml. During adrenaline infusion to the ewes this rose by an amount dependent on the adrenaline concentration achieved and there was also a rise in foetal plasma ACTH but no consistent change in foetal plasma adrenaline. There was no reproducible change in plasma corticosteroid concentration during adrenaline infusion into the foetus but a rise in maternal plasma corticosteroid concentration during infusion into the ewes. Because the adrenaline concentrations achieved during the infusions were within the physiological range, the results indicate that circulating catecholamines may directly or indirectly influence the concentration of ACTH in the circulation. Also, physiological rises in plasma catecholamines in pregnant animals may stimulate the release of ACTH from the foetal pituitary.
A POSSIBLE INTERRELATIONSHIP BETWEEN GONADOTROPHIN STIMULATION AND PROSTAGLANDIN F2α INHIBITION OF STEROIDOGENESIS BY GRANULOSA-LUTEAL CELLS IN VITRO
Authors: HENDERSON K. M. , McNATTY K. P. 
Published: December 2008

SUMMARY
The newly formed corpus luteum of many species is refractory to the lytic action of prostaglandin F2α (PGF2α). This phenomenon was studied utilizing porcine, bovine and human granulosa-luteal cells in tissue culture. The steroidogenic potential of the granulosa-luteal cells was critical in determining whether PGF2α could inhibit progesterone production. Since the steroidogenic potential of the granulosa-luteal cell is related to the amount of LH bound to the cell, the bound LH may protect the granulosa-luteal cells from the lytic action of PGF2α. Finally, a 'see-saw' type of interaction between LH and PGF2α is postulated to account for the resistance of the newly formed corpus luteum to PGF2α
HORMONE RECEPTOR LEVELS AND HORMONE, RNA AND PROTEIN METABOLISM IN THE GENITAL TRACT DURING THE OESTROUS CYCLE OF THE EWE
Authors: MILLER B. G. , MURPHY LEIGH , STONE G. M. 
Published: December 2008

SUMMARY
The concentrations of soluble oestradiol and progesterone receptor proteins and several metabolic activities were measured in the genital tracts of ewes killed on Days 0 (oestrus), 2, 5, 10 or 14 of the oestrous cycle. In caruncular endometrium and in whole uterus the concentrations of oestradiol receptor (pmol steroid bound/mg tissue DNA) were highest at oestrus and declined steadily thereafter to minimal values at Day 14. The concentrations of progesterone receptor were highest on Days 0–5, then declined to low levels on Days 10–14. There was little metabolism of either [3H]oestradiol or [3H]progesterone in minces of whole uterus and with either steroid the pattern of metabolism did not change at any stage of the cycle. The in-vivo rates of synthesis of protein in caruncular endometrium and in isthmic oviduct were highest at or shortly after oestrus (Days 0–2), then declined to low levels on Days 10–14. RNA:DNA ratios in these two tissues were also greatest at oestrus and subsequently fell to minimal values by Day 14. The results are discussed in relation to ovarian secretion of oestradiol and progesterone during the oestrous cycle of the ewe.
PARTURITION IN GOATS: STUDIES ON THE INTERACTIONS BETWEEN THE FOETUS, PLACENTA, PROSTAGLANDIN F AND PROGESTERONE BEFORE PARTURITION, AT TERM OR AT PARTURITION INDUCED PREMATURELY BY CORTICOTROPHIN INFUSION OF THE FOETUS
Authors: CURRIE W. B. , THORBURN G. D. 
Published: December 2008

SUMMARY
Relationships between foetal corticosteroid concentrations, utero-ovarian prostaglandin F (PGF) and maternal peripheral progesterone have been examined in detail in goats shortly before spontaneous parturition at term. Foetal corticosteroids increased during the last 13-11 days of gestation and particularly sharply during the last 3 days and even during advanced labour. About 24 h before parturition, acute releases of PGF were evident in the vein draining the pregnant uterine horn, and these corresponded closely to the time of luteal regression. Further release of PGF occurred when progesterone declined to low levels, probably reflecting the course of labour.
The changes observed before premature parturition, induced by infusing ACTH into foetal goats, were similar except for the more rapid increase in foetal corticosteroid concentrations. Immature neonates born after ACTH treatment were viable, placental delivery was normal and lactogenesis occurred in the mothers indicating that the treatment promoted full expression of the critical perinatal events. The early, acute releases of PGF were ipsilateral to the ACTH-infused foetus and were luteolytic provided the corpora lutea were also on that side. Luteolysis failed or was abnormally delayed if the corpora lutea were contralateral and prolonged ACTH treatment of the foetuses in such cases caused foetal death probably because of premature failure of the placenta. Similar findings were noted if ACTH infusion of the foetus was accompanied by simultaneous progesterone treatment of the mothers in order to block the induction of labour. It was suggested that placental changes occurring during foetal hypercortisolism might be caused by increased placental oestrogen synthesis and the effect of this on the foeto-maternal junction along with a stimulatory action on PG synthesis in the maternal placenta. Experimental disruption of the normal sequence of events, when labour was blocked by progesterone, proved to be lethal to the foetus if the loss of placental integrity progressed sufficiently.
The chain of regulatory signals linking increased activity of the foetal adrenal with parturition thus appears to involve stimulation of oestrogen biosynthesis, PGF release from the maternal placenta and the start of physical changes at the placental junction. Provided the foetus and corpora lutea are ipsilateral, the early releases of PGF effect luteolysis and a withdrawal of progesterone from the maternal circulation. When progesterone concentrations are sufficiently low, labour is initiated and its progress reflected by further release of PGF. The control mechanisms, which also provide for the final maturation of the foetus, clearly enable a close synchronization of the various perinatal events which are essential for the transition from foetal to postnatal life.
CHANGES IN AGGRESSIVE AND SEXUAL RESPONSIVENESS OF MALE GOLDEN HAMSTERS AFTER NEONATAL ANDROGEN ADMINISTRATION
Authors: PAYNE A. P. 
Published: December 2008

SUMMARY
On day 1 after birth, male golden hamsters received either 300 μg of an androgen (testosterone propionate, testosterone, dihydrotestosterone or androstenedione) in 0·03 ml arachis oil, or oil alone. As intact adults, their aggressiveness towards unreceptive females was measured. After this, all animals were castrated. At least 3 weeks after the operation all animals received oestradiol benzoate (10 μg + progesterone (500 μg), after which their capacity to show patterns of female sexual behaviour towards a stud male was tested. Control hamsters which had received oil as neonates showed less aggression than the females with which they interacted; these controls also readily assumed lordosis after castration and priming with ovarian steroids. Conversely, animals which had received testosterone propionate or androstenedione neonatally were as aggressive as the female hamsters, and showed a markedly decreased ability to display lordotic behaviour after castration. The behaviour of male hamsters which received testosterone or dihydrotestosterone was unaffected. Thus, at the level of treatment used, increased aggressiveness appeared to co-vary with a decreased capacity to show female sexual behaviour patterns. However, within each treatment there was little evidence of such a relationship at the level of the individual animal.
AN HOMOLOGOUS RADIOIMMUNOASSAY FOR CHICKEN FOLLICLE-STIMULATING HORMONE: OBSERVATIONS ON THE OVULATORY CYCLE
Authors: SCANES C. G. , GODDEN PATRICIA M. M. , SHARP P. J. 
Published: December 2008

SUMMARY
A highly purified FSH preparation has been used to develop a specific homologous radioimmunoassay for chicken FSH which is sufficiently sensitive and precise to measure the hormone in small samples (10–100μl) of plasma. The assay was used to measure plasma FSH in the chicken and turkey.
The FSH concentration was higher in sexually mature chickens than in juvenile birds and further elevated after castration or ovariectomy. In turkeys, it was lower in birds held on a short daily photoperiod than in birds held on a long daily photoperiod. FSH rose in sexually quiescent female turkeys after injection of synthetic LH-releasing hormone and was increased in laying hens after injection of progesterone.
No major changes were observed in FSH concentration during the chicken ovulatory cycle, although there was a small increase between 15 and 14 h before ovulation.
CHANGES IN PITUITARY RESPONSIVENESS TO LUTEINIZING HORMONE RELEASING HORMONE IN RAMS EXPOSED TO ARTIFICIAL PHOTOPERIODS
Authors: LINCOLN G. A. 
Published: December 2008

SUMMARY
Six adult Soay rams were subjected to an artificial lighting régime of alternating 4 month periods of long days (16 h light: 8 h darkness) and short days (8 h light: 16 h darkness) which induced a seasonal cycle in testicular development and regression during a period of 32 weeks. On 15 occasions during the study pituitary responsiveness was assessed by measuring the concentration of luteinizing hormone (LH) in jugular blood samples collected at frequent intervals after the intravenous injection of 1 pg synthetic luteinizing hormone releasing hormone (LH-RH).
It was shown that both the magnitude and duration of the induced release of LH changed in relation to the photoperiod; the magnitude was greatest during long days when the rams were sexually quiescent, while the duration of the LH release was greatest during short days at the peak of testicular activity. This pattern of responsiveness was modified by implantation of the rams with testosterone.
ANTERIOR PITUITARY SENSITIVITY IN IMMATURE FEMALE RATS STIMULATED WITH GONADOTROPHIN RELEASING HORMONE IN VIVO: EFFECT OF PRIMING WITH OESTROGEN, PREGNANT MARE SERUM GONADOTROPHIN OR BRAIN LESION
Authors: DE ZIEGLER D. , WILKINSON M. , CASSARD DANIELLE , RUF K. B. 
Published: December 2008

An investigation of pituitary sensitivity, assessed in terms of increments in plasma LH and FSH concentrations, to stimulation with one or two injections of gonadotrophin releasing hormone (GnRH) was carried out on 26-day-old immature female rats which had received one of the following priming treatments: 10 μg oestradiol benzoate (OB) as a single injection on day 23 or day 25, or on both days; 10 i.u. pregnant mare serum gonadotrophin (PMSG) on day 24; an electrochemical brain lesion placed in the mediobasal hypothalamus on day 23; control animals received either vehicle alone or a sham lesion.
Pituitary sensitivity assessed at 10.00 h on day 26, after one or two injections of GnRH (100 ng/100 g body weight, s.c.), was enhanced to a similar degree in the three groups treated with OB in terms of LH (P < 0-01). The FSH response also increased after OB treatment but was not statistically significant. In contrast, 48 h after the injection of PMSG (i.e. when the rats were in a 'pro-oestrous-like' condition) pituitary sensitivity in terms of both LH and FSH dropped sharply (P < 0·001). In lesioned animals, pituitary sensitivity to one injection of GnRH was unchanged. A second GnRH injection administered after a 60 min interval induced a slightly larger LH response in control animals. In contrast, the ratio of the second response to the first increased in animals treated with PMSG, despite the state of overall decrease in sensitivity, being 4·5:1 in PMSG-treated rats versus 1·4:1 in controls.
In a second set of experiments, we investigated the variation of pituitary sensitivity in conjunction with an experimentally induced gonadotrophin surge. In animals treated with OB on day 23 and with 1 mg progesterone at 12·00 h on day 26, pituitary sensitivity was increased at both 14.00 and 17.00 h as compared with that in the day 23 OB-treated group at 10.00 h. The PMSG-treated animals maintained their state of decreased responsiveness at 14.00 h, but exhibited increased pituitary sensitivity at the time of the gonadotrophin surge (17.00 h).
These results show that OB increases pituitary sensitivity to GnRH in 26-day-old female rats and that the induction of a gonadotrophin surge further increases this sensitivity. In contrast, PMSG-treated rats displayed a state of decreased responsiveness 48 and 52 h, but not 55 h, after the injection. Pituitary sensitivity on the second day after PMSG treatment thus clearly differs from that observed during pro-oestrus in the adult cyclic female rat.