bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for an increased opioid inhibition of LH secretion in hyperprolactinaemic ovariectomized rats
Authors: Carter D. A. , Cooper J. S. , Inkster S. E. , Whitehead S. A. 
Published: December 2008

ABSTRACT
The effects of acute and sub-chronic hyperprolactinaemia on the positive feedback action of progesterone in oestrogen-primed ovariectomized rats have been compared. A single injection of ovine prolactin administered with progesterone had no effect on the LH surge measured 5 h later although hyperprolactinaemia induced by 5-day treatment with the dopamine antagonist, domperidone, markedly attenuated the surge. Repeated injections of naloxone (5 mg/kg) during the development of the progesterone-stimulated LH surge completely reversed this inhibitory effect of hyperprolactinaemia, but had no apparent effect on the positive feedback action in control animals. In oestrogen-primed animals similar treatment with naloxone (0·4 and 5 mg/kg) stimulated LH secretion but the increase was significantly smaller than that observed after injecting progesterone. It is suggested that hyperprolactinaemia increases the inhibitory opioid modulation of LH release and that this effect is responsible for the impairment of the positive feedback action of progesterone.
J. Endocr. (1984) 101, 57–61
Pars distalis cell quantification in normal adult male and female rats
Authors: Dada M. O. , Campbell G. T. , Blake C. A. 
Published: December 2008

ABSTRACT
We analysed cell types in the pars distalis of normal young adult male and female rats with respect to their percentages and the relative volumes they occupy. In male rats the percentages of the cell types were: prolactin 49·80, GH 22·67, LH 5·04, FSH 4·22, ACTH 2·93 and TSH 2·09, The volume densities were: prolactin 20·48, GH 20·95, LH 7·34, FSH 6·73, ACTH 3·75 and TSH 3·19. In female rats the percentages of the cell types were: prolactin 52·40, GH 20·30, LH 5·89, FSH 4·06, ACTH 2·53, TSH 2·40 and the volume densities were: prolactin 28·09, GH 20·86, LH 8·11, FSH 5·46, ACTH 3·49 and TSH 2·91. The percentages of pars distalis cells which did not stain with the antisera to the six classical hormones were 17·47 in male and 16·48 in female rats.
The results suggest that (1) in both sexes the number (N) of prolactin cells > N of GH cells > N of gonadotrophs > N of TSH or ACTH cells, (2) the percentage of each cell type was similar in both sexes, (3) the volume density (Vv) of prolactin cells was greater than the Vv of GH cells in female but not in male rats and in both sexes the Vv of GH cells > the Vv of gonadotrophs > the Vv of TSH or ACTH cells, (4) in both sexes the volume (V) of prolactin cells < the V of GH cells < the V of gonadotrophs, the V of TSH cells or the V of ACTH cells, (5) the V of prolactin cells was greater in female than in male rats and (6) approximately 17% of the cells in the pars distalis of both sexes did not contain 'immunoreactive' prolactin, GH, LH, FSH, TSH or ACTH.
J. Endocr. (1984) 101, 87–94
Serum oestradiol and preovulatory follicular development before in-vitro fertilization
Authors: Hillier S. G. , Parsons J. H. , Margara R. A. , Winston R. M. L. , Crofton M. E. 
Published: December 2008

ABSTRACT
Twenty-three in-vitro fertilization (IVF) treatment cycles (four unstimulated and 19 clomiphene-stimulated) were assessed retrospectively to discern relationships among serum oestradiol (OE2) titre on the day that human chorionic gonadotrophin (hCG) was given and the number and size of ovulatory follicles available for aspiration of oocytes during laparoscopy 32–38 h after hCG injection. Since 12 of the cycles succeeded to the stage of embryo replacement and two normal term pregnancies resulted, the series as a whole offers a useful referent data base. When only one ovulatory follicle developed (n = 8) the average volume of aspirated follicular fluid was approximately 6 ml, equivalent to a follicular diameter between 22 and 23 mm. When multiple follicles developed (mean 2·7/patient, n = 15), average fluid volume/follicle was not significantly different, averaging approximately 5·5 ml. Serum OE2 titre on the morning before hCG was injected ranged between 0·9 and 5·5 nmol/l and corresponded to the number of follicles aspirated at laparoscopy. There was a highly significant linear correlation (r = 0·85, P <0·001) between this OE2 value (X nmol/l) and total aspirated fluid volume (Y ml) where Y = 2·07 + 3·65 X. Thus taking 6 ml as the 'typical' fluid volume, the calibration line and its 95% confidence limits could be used to establish provisional 'ideal' pre-hCG serum OE2 titre ranges corresponding to the development of one, two or three mature ovulatory follicles. This information, combined with a knowledge of the number of presumptive preovulatory follicles present (assessed by ovarian ultrasound), can aid the timing of the hCG injection before IVF.
J. Endocr. (1984) 101, 113–118
Inhibition of acetylcholine receptor synthesis by thyroid hormones
Authors: Shainberg A. , Brik H. , Bar-Shavit R. , Sampson S. R. 
Published: December 2008

ABSTRACT
Studies were made on the effect of thyroid hormones on the level of acetylcholine receptors (AChR) in cultured rat skeletal muscle. Treatment of differentiated myotubes in vitro with thyroxine (T4; 2 × 10−7 mol/l) for 2–3 days caused a marked decrease in the amount of AChR (P<0·05) and an increase in activity of Na+-K+-ATPase (P<0·05). There was no significant effect of hormone treatment on other muscle proteins, such as creatine kinase and acetylcholinesterase. Measurements of the turnover rate of AChR in T4-treated myotubes showed only a very slight effect of T4 on the rate of AChR degradation. To study the mechanism by which the hormone exerts its effect, muscle cells were labelled with radioactive amino acid and the rate of its incorporation into AChR protein was measured. The AChR was then isolated using anti-AChR antibodies. The specific activity of labelled AChR was lower in hormone-treated cells. These experiments suggest that the decreased level of AChR in response to thyroid hormone treatment is due to a partial suppression of receptor synthesis.
J. Endocr. (1984) 101, 141–147
Ovariectomy does not abolish proceptive behaviour cyclicity in the common marmoset (Callithrix jacchus)
Authors: Kendrick K. M. , Dixson A. F. 
Published: December 2008

ABSTRACT
Unlike in other non-human primates, ovariectomy of the female marmoset did not alter heterosexual interactions. Proceptive behaviour bouts retained the same cyclicity, duration and frequency within tests as during the ovarian cycle. Significant rises in plasma levels of cortisol, progesterone, oestrone and testosterone were found during these proceptive behaviour bouts and in cortisol, progesterone and oestrone at their onset. Results suggest a role for adrenocortical steroids in both maintaining female sexuality and regulating its cyclicity during ovarian cycles in this primate.
J. Endocr. (1984) 101, 155–162
Ovarian steroid metabolism and oestrogens in the corpus luteum of the tammar wallaby
Authors: Renfree M. B. , Flint A. P. F. , Green S. W. , Heap R. B. 
Published: December 2008

ABSTRACT
Ovaries were obtained from tammar wallabies at various stages of the reproductive cycle to examine the occurrence of oestrogens in corpora lutea, and the synthesis and metabolism of steroids in the corpus luteum and ovarian cortical and interstitial tissues. Corpora lutea contained oestradiol-17β and oestrone during embryonic diapause and at all stages of pregnancy studied after blastocyst activation. Aryl sulphatase, 3β-hydroxysteroid dehydrogenase and 17β-oxidoreductase were shown to be present in luteal and other ovarian tissues by incubation in vitro with labelled substrates. Aromatase was undetectable in corpora lutea or in interstitial tissue, but was present in the ovarian tissues (including follicles) which remained after removal of corpora lutea. The probable source of the oestrogens detected in the corpus luteum is discussed in relation to their role in the inhibition of follicular development during embryonic diapause.
J. Endocr. (1984) 101, 231–240
Cyclic GMP phosphodiesterase and guanylate cyclase activities in rabbit ovaries and the effect of in-vivo stimulation with LH
Authors: Patwardhan V. V. , Lanthier A. 
Published: December 2008

ABSTRACT
The activities of guanylate cyclase and cyclic GMP (cGMP) phosphodiesterase, enzymes that are responsible for maintaining tissue levels of cGMP, were determined in the ovaries of rabbits killed without treatment or 4 h after administration of LH. Ovarian activities of the two enzymes were determined in the 100 000 g supernatant fraction (cytosol) and the resulting pellet (particulate fraction). Significant phosphodiesterase and cyclase activities were detected in both the cytosol and particulate fractions. Administration of LH had no significant effect on phosphodiesterase activity in either of the tissue fractions. On the other hand, LH caused a significant drop in guanylate cyclase activity in the cytosol and particulate fractions. This drop in the cyclase activity may be the cause of the decreased rabbit ovarian concentrations of cGMP that we have previously observed after LH stimulation.
J. Endocr. (1984) 101, 305–310
Histochemical studies on steroid dehydrogenases in the testis of the goat (Capra hircus)
Authors: Bilaspuri G. S. , Guraya S. S. 
Published: December 2008

ABSTRACT
Detailed histochemical localization of 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-HSD was made in the goat testis using both NAD and NADP coenzymes. The substrates used for 3β-HSD were dehydroepiandrosterone (DHA) and pregnenolone whereas 17β-HSD was localized with testosterone and oestradiol. In general, the activity of the enzymes varied with the cell type, substrate and coenzyme. In seminiferous tubules, DHA and NAD were the preferred substrate and coenzyme respectively for 3β-HSD. In addition, in interstitial tissue, NAD was the preferred coenzyme with DHA whereas no such preference existed with pregnenolone. 17β-Hydroxysteroid dehydrogenase showed a similar pattern in the two main compartments of the testis, as testosterone and oestradiol were equally utilized and NAD was the preferred coenzyme in both these compartments. The activities of the enzymes increased during the process of spermiogenesis and were higher in seminiferous tubules than in interstitial tissue, especially in elongated spermatids and spermatozoa.
J. Endocr. (1984) 101, 359–363
Ovarian oestrogen-dependent maturation of the LH/FSH surge mechanism during prepubertal development in the gilt
Authors: Foxcroft G. R. , Elsaesser F. , Stickney K. , Haynes N. B. , Back H. L. 
Published: December 2008

ABSTRACT
An involvement of ovarian secretions and in particular oestradiol-17β in the maturation of the positive feedback mechanism controlling gonadotrophin surge secretion was studied in prepubertal gilts. The LH/FSH responses to an intramuscular injection of age- and body weight-related doses of oestradiol benzoate (OB) were compared in intact gilts at 60 days of age with or without oestradiol-17β pretreatment from 30 to 52 days of age. Four further groups of gilts were challenged with OB at 160 days and were intact, ovariectomized at 60 days, ovariectomized at 60 days and given oestrogen therapy from days 60 to 130 or ovariectomized at 130 days.
A significant increase in the magnitude of LH surge responses to OB and a decrease in the time to the first consistent period of surge secretion in intact gilts at 160 compared to 60 days of age confirmed earlier studies and is considered to represent a real maturational change in positive feedback activity. A longer response interval was also present in the majority of ovariectomized gilts. Furthermore a significant reduction in the magnitude of OB-induced LH responses at day 160 occurred in gilts ovariectomized at day 60 compared to those ovariectomized at day 130 and with intact control animals. Oestrogen therapy after ovariectomy at day 60 effectively restored the magnitude of the LH response however.
It is concluded that maturation of the positive feedback mechanism is ovarian, and probably oestrogen, dependent.
J. Endocr. (1984) 101, 371–380
Anaesthesia with alphaxalone plus alphadolone acetate blocks the oestrogen-stimulated LH surge and impairs pulsatile LH secretion in ovariectomized female rats
Authors: Dyer R. G. , Mansfield S. 
Published: December 2008

ABSTRACT
Two experiments were undertaken to assess further the action of the steroid anaesthetic alphaxalone upon LH secretion in chronically ovariectomized female rats.
For the first experiment, 31 rats were given two injections of oestradiol benzoate (20 μg/100 g body weight), each 72 h apart, to stimulate an LH surge 6 h after the second injection. However, one group of seven rats was anaesthetized with alphaxalone throughout the 6-h period and a second group of eight was similarly anaesthetized only for the last 2 h of the 6-h period. The steroid-stimulated LH surge was blocked in both groups of rats anaesthetized with alphaxalone.
The second experiment involved a comparison of pulsatile LH secretion in animals which were either unanaesthetized (n = 8) or anaesthetized with alphaxalone (n = 9). In six out of nine rats the anaesthetic did not affect the maximum or minimum plasma LH concentrations but significantly slowed the frequency at which LH pulses were measured. In the remaining three anaesthetized rats the drug blocked pulsatile LH secretion.
The experiments confirm that some secretion of LH continues during alphaxalone anaesthesia but indicate also that the drug has a more deleterious action upon the oestrogen-stimulated LH surge than believed hitherto.
J. Endocr. (1984) 102, 27-31
Interaction of epidermal growth factor with receptors on human and porcine thyroid membranes
Authors: Humphries H. , MacNeil S. , Munro D. S. , Tomlinson S. 
Published: December 2008

ABSTRACT
Recent evidence suggests that epidermal growth factor (EGF) may play an important role in the regulation of thyroid growth and function. We have examined the interaction of murine EGF (mEGF) with human and porcine thyroid membranes and compared this with the binding of bovine TSH (bTSH) using 125I-labelled hormones as tracers. The characteristics of the binding of mEGF were found to be similar for human and porcine thyroid membranes. Epidermal growth factor bound with high affinity (affinity constant = 1·4 × 109 l/mol); the density of binding sites was low compared with the TSH receptor. At 37 °C, the binding of 125I-labelled EGF was maximal at 1 h and was saturable in the presence of unlabelled EGF; half-maximal inhibition was at 1 ng EGF/tube (0·5 nmol/l) using 0·5 mg membrane protein/tube. Unlabelled bTSH had no effect on the binding of labelled EGF. Similarly, unlabelled EGF did not affect the binding of labelled TSH; hence it was concluded that mEGF and bTSH bound to independent sites. Epidermal growth factor had no effect on adenylate cyclase activity in membranes prepared from human non-toxic goitre; increasing concentrations of EGF did not affect basal, TSH-stimulated or fluoride-stimulated enzyme activity.
J. Endocr. (1984) 102, 57–61
Release of oxytocin and vasopressin by magnocellular nuclei in vitro: specific facilitatory effect of oxytocin on its own release
Authors: Moos F. , Freund-Mercier M. J. , Guerné Y. , Guerné J. M. , Stoeckel M. E. , Richard Ph. 
Published: December 2008

ABSTRACT
The release of endogenous oxytocin and vasopressin by rat paraventricular and supraoptic nuclei in vitro during a 10-min period, 30 min after beginning the incubation, was measured radioimmunologically. Mean basal hormone release per 10 min and per pair of nuclei was: 128·4 ± 12·4 (s.e.m.) pg vasopressin (n = 15) and 39·0 ± 3·0 pg oxytocin (n = 66) for supraoptic nuclei from male rats; 273·9 ± 42·6 pg vasopressin (n = 11) and 34·2 ± 3·5 pg oxytocin (n = 15) for supraoptic nuclei from lactating rats; 70·0 ± 8·6 pg vasopressin (n = 52) and 21·8 ± 1·3 pg oxytocin (n = 68) for paraventricular nuclei from male rats; 59·1 ± 8·6 pg vasopressin (n = 10) and 27·0 ± 4·6 pg oxytocin (n = 16) for paraventricular nuclei from lactating rats.
In male and lactating rats, both nuclei contained and released more vasopressin than oxytocin. For oxytocin alone, the paraventricular nucleus of male rats contained and released significantly less hormone than the supraoptic nucleus. This difference was not apparent in lactating rats. For vasopressin alone, the paraventricular nucleus contained and released significantly less hormone than the supraoptic nucleus in both male and lactating rats. When the hormone released was calculated as a percentage of the total tissue content the release was about 0·9% for oxytocin from both nuclei in male and lactating rats and also for vasopressin in lactating rats, but was only about 0·5% for vasopressin from both nuclei in male rats.
The influence of oxytocin and analogues of oxytocin (including one antagonist) upon the release of oxytocin and vasopressin was studied. Adding oxytocin to the incubation medium (0·4–4 nmol/l solution) induced a dose-dependent rise in oxytocin release from both nuclei of male or lactating rats. A 4 nmol/l solution of isotocin had a similar effect to a 0·4 nmol/l solution of oxytocin, but arginine-vasopressin never affected basal release of oxytocin. In no case was vasopressin release modified.
An oxytocin antagonist (1 μmol/l solution) significantly reduced basal oxytocin release and blocked the stimulatory effect normally induced by exogenous oxytocin, as did gallopamil hydrochloride (D600, 10 μmol/l solution), a Ca2+ channel blocker, or incubation in a Ca2+-free medium.
These findings are discussed in relation to the literature on the central effects of neurohypophysial peptides. It may be concluded that the regulatory role of endogenous oxytocin in the hypothalamus on the milk-ejection reflex could result from its local release in the extracellular spaces of magnocellular nuclei.
J. Endocr. (1984) 102, 63–72
A novel oestrogen-binding species in rat granulosa cells
Authors: Kudolo G. B. , Elder M. G. , Myatt L. 
Published: December 2008

ABSTRACT
The dissociation constants (Kd) and steroid specificities of oestrogen-binding species in rat granulosa cell cytosol and nuclei have been studied. Preliminary work, where diethylstilboestrol was employed as competitor in binding assays, identified the oestrogen receptor in whole ovarian tissue nuclei (Kd 0·35 ±0.09 nmol/l) and cytosol (Kd 0·39 ± 0·03 nmol/l). Isolation of granulosa cells revealed that the majority of this receptor (75–96%) was present in these cells. Specificity studies on the binding of [3H]oestradiol in granulosa cell cytosol indicated the presence of an additional class of oestrogen-binding sites which were, however, not present in nuclei. Saturation analysis over an extended range of [3H]oestradiol concentrations and using unlabelled oestradiol as competitor revealed a binding species of Kd 45·8± 6·9 nmol/l (capacity 16·7 pmol/mg cytosol protein) for oestradiol in addition to the cytosol oestrogen receptor of Kd 0·58 ± nmol/l (capacity 2·8 pmol/mg cytosol protein). The low affinity of this novel species implies that the dextran-coated charcoal techniques used in previous studies on ovarian oestrogen-binding species would cause dissociation of ligand and not allow it to be measured.
The second oestrogen-binding species displayed affinity for oestradiol-17β, oestriol, oestrone, testosterone, 5α-dihydrotestosterone, methyltrienolone, progesterone and the antioestrogens tamoxifen, nafoxidine and clomiphene citrate. The species, however, did not bind diethylstilboestrol, a characteristic shared with other low affinity cytosol oestrogen-binding species which have been reported in dog prostate, chick oviduct and male rat liver but not shared with uterine type II oestrogen receptors. It can be further distinguished from the oestrogen receptor by differential ammonium sulphate precipitation and the stability of its ligand binding at temperatures above 55 °C where the oestrogen receptor–ligand interaction is rapidly lost.
Concentrations of nuclear oestrogen receptor in granulosa cells (2200 sites/cell) were similar to those found in other target tissues but a high proportion of this receptor (70%) was 'unoccupied' or available for binding at 4 °C and the majority (75%) was resistant to extraction with 0·4 m-KCl. As the second oestrogen-binding species could not be detected in granulosa cell nuclei it is unlikely to be involved directly in eliciting genomic responses to hormonal stimulation. It is more probable that it regulates the level of the free intracellular steroid to which the oestrogen receptor of the granulosa cell (the predominant site of oestrogen biosynthesis) is exposed.
J. Endocr. (1984) 102, 83–91
Sexual maturation in male mice treated with cyproterone acetate from birth to puberty
Authors: Jean-Faucher Ch. , Berger M. , De Turckheim M. , Veyssiere G. , Jean Cl. 
Published: December 2008

ABSTRACT
Cyproterone acetate was administered every 2 days from 1 to 39 days of age to male mice which were killed 24 h or 20 days after the last injection. Cyproterone acetate caused a significant reduction in the relative weights of the epididymis, vas deferens, seminal vesicle and preputial gland, which was still evident at 60 days after birth. Testicular and epididymal androgens (testosterone and dihydrotestosterone) and circulating LH and FSH concentrations were equal to or higher than those of controls at 60 days. Cyproterone acetate did not inhibit spermatogenesis but all males were infertile. The results suggest that the peripheral effects of testosterone are necessary, during early stages of sexual maturation, in order to obtain subsequent full development of the accessory sex organs.
J. Endocr. (1984) 102, 103–107
The inhibitory effect of opiates on gonadotrophin secretion is dependent upon gonadal steroids
Authors: Bhanot R. , Wilkinson M. 
Published: December 2008

ABSTRACT
We have attempted to clarify the physiological involvement of endogenous opiates in the steroid-mediated control of gonadotrophin release. Our studies showed that there was an acute reduction in the inhibitory effects of endogenous opiates on LH and FSH release following gonadectomy in the rat. This was indicated by a significant reduction in the ability of naloxone to stimulate serum LH/FSH levels (sampled at 15 min) in 26-day-old female rats 48 h after ovariectomy. Luteinizing hormone was highly sensitive to the inhibitory effects of the synthetic met-enkephalin analogue, FK 33-824, at this time (sampled at 90 min). An unexpected observation was that long-term absence of gonadal steroids also disrupted the ability of exogenous opiates, FK 33-824 and morphine, to influence LH release. This was seen as an inability of FK 33-824 (1·0 or 3·0 mg/kg) to inhibit LH secretion. The effects of gonadectomy on opiate control of LH occurred at all developmental stages and were not due to a disruption of sexual maturation. Opiate involvement in prolactin secretion did not appear to be adversely affected by an absence of gonadal steroids. Another novel aspect of this work was that the opiatergic component in the control of gonadotrophin secretion could be reinstated in long-term gonadectomized rats by treatment with oestradiol benzoate or testosterone propionate. Similarly, priming with increasing dosages of oestradiol benzoate which resulted in progressively lower LH levels gave larger naloxone responses. This steroid–opiate interdependency suggests that the negative feedback influence of gonadal steroids on LH secretion is conveyed, in part, by hypothalamic opiate peptides. Our results therefore provide a neurochemical basis for gonadal steroid negative feedback.
J. Endocr. (1984) 102, 133–141