bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for the involvement of central conversion of testosterone to oestradiol-17β in the regulation of luteinizing hormone secretion in the cockerel
Authors: Wilson S. C. , Knight P. G. , Cunningham F. J. 
Published: December 2008

Treatment of intact cockerels with the synthetic antioestrogen tamoxifen caused a significant increase in the plasma concentration of LH. In contrast, passive immunization with an antiserum raised against oestradiol-17β did not lead to an increase in plasma LH. A pronounced depressive effect of injections of 0·1 mg testosterone propionate (TP) or 0·1 mg oestradiol benzoate (OB) on plasma concentrations of LH was prevented by tamoxifen. Furthermore, a pronounced rise in the concentration of LH releasing hormone in the posterior hypothalamus after the injection of cockerels with OB was completely inhibited by tamoxifen. Neither 0·1 nor 0·5 mg androstenedione modified the concentration of LH in plasma.
A dose of 0·05 mg TP, which failed to depress the concentration of LH in plasma of intact cockerels, caused a marked fall in plasma LH in castrated cockerels. Tamoxifen itself exhibited weak oestrogen agonist activity in castrated cockerels by causing a reduction in the concentration of LH in plasma. However, tamoxifen prevented any further depressive effect on LH resulting from the injection of TP. These findings suggest that testosterone exerts an inhibitory influence on LH secretion at the central neural level, partially at least, by means of the product of its aromatization, oestradiol-17β.
Response of transcortin and α2u-globulin to turpentine-induced inflammation in the rat: influence of corticosteroids and prolactin
Authors: Faict D. , Vandoren G. , De Moor P. , Lesaffre E. , Verhoeven G. 
Published: December 2008

Evidence is presented that transcortin and α2u-globulin react as negative acute-phase proteins in the rat. Thirty-six hours after turpentine injection, the serum concentration of these proteins showed a two- to threefold decrease. Thereafter, transcortin rapidly returned to normal values, whereas α2u-globulin remained low.
This reaction pattern was still present after adrenalectomy, adrenalectomy and administration of glucocorticoids, and after treatment with bromocriptine, a suppressor of prolactin secretion. It is concluded that changes in the secretion of glucocorticoids and prolactin are not required for the observed turpentine-induced decrease of transcortin and α2u-globulin.
Sustained oestrogen-induced hyperprolactinaemia results from a pituitary defect
Authors: Willoughby J. O. , Pederick H. J. , Jervois P. M. , Menadue M. F. 
Published: December 2008

Pituitary enlargement and hyperprolactinaemia were induced in male rats by a single subcutaneous injection of 2 mg oestradiol benzoate in oil. Two months after treatment, when oestrogen levels were normal, serial blood samples for determination of plasma concentrations of prolactin were obtained from undisturbed animals through an indwelling right atrial cannula which had been implanted 7–10 days before.
Basal concentrations of prolactin were obtained in treated and control rats, and responses of prolactin to intravenous injections of thyrotrophin releasing hormone (TRH), apomorphine, butaclamol and fenfluramine were measured.
Sustained hyperprolactinaemia with pituitary hyperplasia was achieved in only 20% of animals. Responses of prolactin to TRH were the same in control, oestrogen-treated hyperprolactinaemic and non-hyperprolactinaemic rats, indicating normal pituitary responsiveness to one prolactin releasing factor.
Complete suppression of prolactin concentrations by apomorphine occurred in hyperprolactinaemic animals, whereas no suppression could be demonstrated in animals with normal (low) basal prolactin levels, indicating good responsiveness of hyperplastic pituitary glands to dopamine inhibition.
Dopamine receptor blockade by butaclamol resulted in a vigorous prolactin response in animals with sustained hyperprolactinaemia, indicating that dopaminergic prolactin inhibitory mechanisms remain qualitatively intact, but the response was quantitatively less than in controls, suggesting insufficient hypothalamic release of dopamine.
Responses of prolactin to certain doses of fenfluramine were completely abolished in hyperprolactinaemic animals, indicating diminished sensitivity of serotoninergic prolactin releasing factor mechanisms.
Prolactin releasing factor unresponsiveness and relative insufficiency of dopaminergic activity could be regarded as physiologically appropriate responses to chronic hyperprolactinaemia. Thus oestrogen-induced chronic hyperprolactinaemia appears to be entirely of pituitary origin.
Changes in testosterone metabolism by the brain and cloacal gland during sexual maturation in the Japanese quail (Coturnix coturnix japonica)
Authors: Balthazart J. , Schumacher M. 
Published: December 2008

ABSTRACT
Testosterone metabolism in the brain and pituitary and cloacal glands of male and female Japanese quail was studied in vitro during sexual maturation (from 1 day to 5 weeks after hatching).
The production of 5α-dihydrotestosterone in the hyperstriatum and cloacal gland and that of androstenedione in the cloacal gland of males was highest at 1 day after hatching, which could be related to the peak of plasma androgens previously demonstrated in neonatal quail. 5β-Reductase activity was very high in the brain, but not the pituitary or cloacal glands of young chicks and decreased markedly, especially in the hypothalamus, during sexual maturation. As 5β-reduced metabolites of testosterone are inactive androgens, it is suggested that the decrease of 5β-reductase activity with age corresponds to a potentiation of the effects of testosterone at the level of the brain.
J. Endocr. (1984) 100, 13–18
Neonatal exposure to a progestin via milk alters subsequent LH cyclicity in the female rat
Authors: Holzhausen C. , Murphy S. , Birke L. I. A. 
Published: December 2008

ABSTRACT
Medroxyprogesterone acetate (MPA; 5 μg/g body wt) or norethisterone oenanthate (NET-OEN; 4 μg/g body wt) was given to lactating female rats by subcutaneous injection 1 day after parturition. Each female suckled ten female pups which had been randomly allocated to her and at 21 days of age the pups were weaned. In this way female pups were exposed to either MPA or NET-OEN via milk during suckling. The patterns of LH and progesterone secretion at pro-oestrus were investigated using radioimmunoassay. When these pups reached adulthood it was found that neonatal exposure to MPA via milk significantly reduced the pro-oestrous LH peak by 45% as well as the total amount (by 27%) of LH secreted during pro-oestrus. Neonatal exposure via milk to NET-OEN had no effect on LH secretion during pro-oestrus. Pro-oestrous progesterone secretion was unaffected by either MPA or NET-OEN treatment.
J. Endocr. (1984) 100, 149–154
Studies on the control of gonadotrophin release in the gonadectomized male rat: evidence for a lack of involvement of the hypothalamic noradrenergic system in the long-term castrated rat
Authors: Herdon H. J. , Everard D. M. , Wilson C. A. 
Published: December 2008

ABSTRACT
The effects of castration with or without testosterone replacement in the adult male rat were studied to investigate possible hypothalamic mechanisms by which changes in gonadotrophin secretion occur at different times after castration, with particular reference to the continuing LH rise and its lack of suppression by testosterone in the long-term castrated rat. Castrated rats received either subcutaneous silicone elastomer implants containing testosterone or empty implants at the time of castration, and a sham-operated group served as controls.
At 1, 10 and 40 days after castration, there were six-, 15- and 25-fold rises respectively in LH and 1·5-, two-and fivefold rises in FSH. However, there were no significant changes in hypothalamic noradrenaline concentration and turnover or in α-adrenoceptor density and affinity at any time after castration. Testosterone implants were effective in suppressing gonadotrophin release at 1 and 10 days, but not at 40 days after castration, and did not significantly affect hypothalamic noradrenaline turnover or α-adrenoceptors at any time.
Neither acute inhibition of the noradrenergic system, using either the α-adrenoceptor blockers phenoxybenzamine and phentolamine or the synthesis inhibitor α-methyl-p-tyrosine, nor chronic depletion of hypothalamic noradrenaline by 6-hydroxydopamine had any significant effect on the normal rise in LH levels seen on days 10 and 40 after castration, and did not alter the ability of testosterone to suppress LH levels. This indicates that, in the long-term castrated rat, the noradrenergic system may not be involved in the control of gonadotrophin release. However, at 16 h after castration, α-adrenoceptor blockers and α-methyl-p-tyrosine did reduce LH levels, indicating that the noradrenergic system is likely to be involved in the short-term response to castration.
J. Endocr. (1984) 100, 235–244
Sex differences in behavioural androgen sensitivity: possible role of androgen metabolism
Authors: Mode A. , Gustafsson J.-Å. , Södersten P. , Eneroth P. 
Published: December 2008

ABSTRACT
Masculine sexual behaviour was induced in castrated sexually inactive but experienced male rats by testosterone-filled constant-release implants or daily injections of the synthetic androgen 17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (methyltrienolone, R 1881), which resists metabolism by target organs. Feminization of the hepatic androgen metabolism by subcutaneous implantation of osmotic minipumps, which delivered a constant amount of human GH, did not affect the behavioural response of castrated rats to testosterone. Testosterone implants were only minimally effective in inducing male behaviour in ovariectomized female rats, but R 1881 was as effective in stimulating male behaviour in females as in males. Testosterone-treated but not R 1881-treated females showed pronounced female sexual behaviour in response to progesterone treatment despite the absence of measureable amounts of oestradiol-17β in peripheral blood. The results provide evidence that masculine sexual behaviour can be activated by an androgen in the absence of oestrogenic stimulation and suggest that the sex difference in the behavioural response to testosterone may be due to a sex difference in the metabolism of androgens by the brain.
J. Endocr. (1984) 100, 245–248
Inhibitory effect of androgen on the synthesis of proteinase F in the male mouse submandibular gland
Authors: Hosoi K. , Tanaka I. , Murai T. , Ueha T. 
Published: December 2008

ABSTRACT
Androgenic regulation of one of the esteroproteinases (proteinase F) in the mouse submandibular gland was studied using specific antiserum. In contrast to esteroproteinases such as proteinases A, D or P-esterase, proteinase F content in male but not in female mice was increased by gonadectomy and decreased by the injection of various androgens. In-vivo incorporation of [3H]leucine into proteinase F in males was increased after castration and decreased by the injection of testosterone propionate; androgens inhibited the denovo synthesis of proteinase F in male mice. The dose–response curves for testosterone propionate and time-courses following castration or after the injection of testosterone propionate were reciprocal between proteinase F and total esteroproteinase activity. Proteinase F, like other esteroproteinases in the submandibular gland of the mouse, was localized in granular convoluted tubular cells. These data indicate that granular convoluted tubular cells of the male mouse submandibular gland synthesize both androgen-inducible proteinases and androgen-inhibitory proteinase (proteinase F).
J. Endocr. (1984) 100, 253–262
Effect of stress on tissue and plasma levels of immunoreactive β-endorphin in ovariectomized rats primed with oestrogen and progesterone
Authors: Hulse G. K. , Coleman G. J. 
Published: December 2008

ABSTRACT
The aim of this study was to investigate the effect of oestrogen and progesterone on levels of immunoreactive β-endorphin (Ir-β-EP) in the hypothalamus, anterior pituitary gland, neurointermediate lobe and plasma under normal conditions and conditions of stress. The injection of oestrogen + progesterone into ovariectomized rats increased Ir-β-EP levels in extracts of anterior pituitary tissue and in plasma, under both normal and stressed conditions. Exposure to a stress reduced the content of anterior pituitary Ir-β-EP in ovariectomized rats treated with oestrogen + progesterone and also with sesame oil. Such treatment only resulted in increments in plasma Ir-β-EP in oil-treated but not in oestrogen + progesterone-treated overiectomized rats. It was concluded (1) that oestrogen and progesterone are involved in the regulation of resting levels of anterior pituitary Ir-β-EP during the rat oestrous cycle, (2) that stress reduces levels of anterior pituitary Ir-β-EP and (3) that increased levels of plasma oestrogen + progesterone inhibit plasma Ir-β-EP increments which normally accompany exposure to stress.
J. Endocr. (1984) 100, 277–280
Simultaneous production of monoclonal antibodies to dehydroepiandrosterone, oestradiol, progesterone and testosterone
Authors: Fantl V. E. , Wang D. Y. 
Published: December 2008

ABSTRACT
Mice were immunized with a mixture of four steroid antigens: dehydroepiandrosterone (DHA), oestradiol, progesterone and testosterone linked to bovine serum albumin through the 7, 6, 11α and 17β positions respectively. The response to immunization varied widely with no one mouse producing an optimal response to all four steroids. In the two fusion experiments performed, antibodies to all four antigens were developed. Data are presented which show that the immune response of the spleen donor is related to the relative numbers and quality of the antibodies produced to each steroid. Despite the structural identity of the progesterone and testosterone haptens, antibodies elicited in response to their respective antigens could readily be distinguished from each other.
From the large number of monoclonal antibodies obtained those most useful for radioimmunoassay were three high affinity antibodies to oestradiol and two antibodies raised against DHA but with high affinity for DHA sulphate.
J. Endocr. (1984) 100, 367–376
Induction of germinal vesicle breakdown in Xenopus laevis oocytes: synergistic action of progesterone and insulin
Authors: Le Goascogne C. , Hirai S. , Baulieu E.-E. 
Published: December 2008

ABSTRACT
Progesterone is the hormone that reinitiates the meiotic division of amphibian oocytes and insulin and insulin-like growth factors are also active on defolliculated oocytes in vitro. We have studied Xenopus laevis oocytes (stage 5–6) of different hormonal sensitivities, obtained from unstimulated and from human chorionic gonadotrophin-stimulated females. Some oocytes from unstimulated females were also precultured with a subthreshold level of progesterone. A dose-dependent potentiating effect of the action of progesterone was observed with insulin, and this was particularly remarkable in low-sensitivity oocytes. Since in the presence of insulin, the optimally effective concentration of progesterone was much reduced (as an example from 1 μmol/l to 50 nmol/l), it is suggested that an insulin-like growth factor may play a physiological role in the reinitiation of meiosis in ovaries.
J. Endocr. (1984) 101, 7–12
Involvement of prolactin in the onset of puberty in female rats
Authors: Gonzalez M. D. , López F. , Aguilar E. 
Published: December 2008

ABSTRACT
Pimozide (1 mg/kg per day), bromocriptine (1 mg/kg per day) or domperidone (0·1 mg/kg per day) administered daily to rats from day 21 did not change the age at which vaginal opening occurred, nor did they affect the body weight at that age. Therefore the evolution of prolactin levels was different in these three groups. The pimozide-treated group showed high prolactin levels measured on day 23, at vaginal opening and at first oestrus. In the bromocriptine-treated group, levels were undetectable on the day of vaginal opening. Chronic treatment with domperidone failed to increase prolactin levels on day 23 and at vaginal opening. Nevertheless, large increases were observed after a single injection of domperidone at both 21 and 30 days of age.
A significant increase in LH observed on day 23 in the pimozide-treated group was the only effect on gonadotrophin levels which was detected. Ovarian weights were unaffected by the treatments, whereas adrenal weight was increased in the bromocriptine-treated group and decreased in the pimozide- and domperidone-treated groups.
Female rats grafted on day 21 with one additional pituitary gland from adult (90 days) or young (21 days) donors showed a similar advancement in the time of vaginal opening, although the animals bearing an adult pituitary gland showed higher prolactin levels than those observed in animals grafted with young pituitary glands.
This study suggested that the onset of puberty is not closely linked with the evolution of prolactin levels and that the hormone itself is not indispensible for the process.
J. Endocr. (1984) 101, 63–68
Effect of changes in litter size at mid-lactation on lactation in rats
Authors: Grigor M. R. , Sneyd M. J. , Geursen A. , Gain K. R. 
Published: December 2008

ABSTRACT
The effect of altering the number of pups per litter from ten to two or two to ten at day 14 of lactation in rats was investigated. Reducing litter size had no effect on the daily live weight gain whereas increasing the litter size resulted in an initial weight loss followed by an impaired weight gain. Maternal food consumption decreased to values appropriate for rats feeding two pups within 2 days after litter reduction, but required at least 5 days after the increase in litter size to increase to values appropriate for rats feeding large litters from parturition. Altering the litter size resulted in maternal serum insulin concentrations that were intermediate between those expected for rats feeding two or ten pups from parturition. Maternal serum prolactin concentrations increased after litter sizes were increased and decreased initially after litter reduction before being restored to normal levels. The activities of the lipogenic enzymes, fatty acid synthase, glucose-6-phosphate dehydrogenase and 'malic' enzyme in the mammary gland all decreased within 72 h of litter reduction to levels appropriate for rats feeding two pups. Although all three enzymes increased in activity after litter size increase, only fatty acid synthase had reached values appropriate for rats feeding ten pups by 72 h.
J. Endocr. (1984) 101, 69–73
Effects of continuous administration of oxytocin by an Accurel device on parturition in the rat and on development and diuresis in the offspring
Authors: Boer G. J. , Kruisbrink J. 
Published: December 2008

ABSTRACT
A controlled-delivery module based on microporous Accurel polypropylene tubing, implanted subcutaneously in the rat, was used to release oxytocin for at least 40 days both in vitro and in vivo. Using a dosage rate of approximately 650 ng oxytocin per day and implanting the device in rats on day 17 of pregnancy, the known physiological action of oxytocin in advancing labour was confirmed. The increased concentrations of oxytocin in the mothers gave rise to adverse effects; the course of labour was protracted during expulsions of the first pups and the birth weight was reduced. Postnatally, body development of the pups was also affected, although there was partial recovery when the pups started to feed independently. Both pre- and postnatal exposure of pups to an oxytocin-treated mother reduced their body water turnover measured at 1 month of age.
The effects on the course of parturition and during lactation might be explained by a blockade of uterine and mammary gland oxytocin receptors respectively, thereby inhibiting a proper response to pulsatile endogenous oxytocin secretion. The changes in water metabolism, which are opposite to those described for the heterologous hormone vasopressin, are less easy to explain since maternal oxytocin is not supposed to pass the placenta. The results may indicate that clinical use of oxytocin for induction of labour and lactation may have hitherto unrecognized side-effects.
J. Endocr. (1984) 101, 121–129
Relationship between glucose and 20α-hydroxysteroid dehydrogenase in fetal sheep erythrocytes
Authors: Nancarrow C. D. , Connell P. J. , Stevens D. 
Published: December 2008

ABSTRACT
We have examined whether glucose supply to fetal sheep erythrocytes limits the rate of 20α-reduction of progesterone in blood and as such is associated with the progressive loss of 20α-hydroxysteroid dehydrogenase activity which has been observed from 30 days before term.
Enzyme activity in erythrocytes depleted of glucose by washing was regained in the presence of at least 0·167 mmol glucose/l. The cofactor NADPH was necessary to support the reaction in lysed cells. Addition of glucose to whole blood diluted 20-fold for assay of 20α-hydroxysteroid dehydrogenase did not increase the rate of reaction. Infusion of dextrose to increase fetal plasma glucose concentrations had no effect on 20α-hydroxysteroid dehydrogenase activity. Over the period from 114 to 137 days of gestation, both dextrose- and saline-infused fetuses showed a decline in enzyme activity from a combined mean of 1·45 ± 0·21 (s.e.m.) to a mean of 0·78 ± 0·18 μmol/ml erythrocytes per h. Fetal leucocytes did not contribute significantly to the activity of 20α-hydroxysteroid dehydrogenase in whole blood.
The rate of 20α-reduction of progesterone in the blood of eight fetuses with indwelling carotid catheters declined from 2·31 ± 0·09 μmol/ml erythrocytes per h at 90–95 days of gestation to 0·73 ± 0·04 μmol/ml per h at 141–145 days. However, a consistent decline was only observed after 116–120 days. The apparent equilibrium position for progesterone reduction to 20α-dihydroprogesterone varied between 83·9 ± 1·8 and 65·7 ± 4·2%.
Thus, it appears that the decline in 20α-hydroxysteroid dehydrogenase activity which occurs in whole blood of sheep fetuses during the last 30 days of gestation is due to dilution of the fetal erythrocytes with adult-type erythrocytes rather than development of limiting concentrations of plasma glucose.
J. Endocr. (1984) 101, 131–139
Decrease of morphine-induced prolactin release by a procedure causing prolonged stress
Authors: Fekete M. I. K. , Kanyicska B. , Szentendrei T. , Simonyi Á. , Stark E. 
Published: December 2008

ABSTRACT
The effects of morphine and fentanyl on plasma prolactin levels in rats have been measured. It was found that a prolonged immobilization stressful procedure for 5 h inhibited the response to morphine and fentanyl to increase prolactin secretion, but did not influence the increase in plasma prolactin caused by haloperidol. The injection of a large dose of cortisol (25 mg/kg, s.c.) also evoked an inhibition of morphine-induced prolactin release. The inhibition was maximal 24 h after the administration of the glucocorticoid. These results indicate that stress may induce prolonged alteration in endogenous opioid-mediated neuro-modulation via a prolonged release of glucocorticoids.
J. Endocr. (1984) 101, 169–172