bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of lactation and season on plasma prolactin concentrations and response to bromocriptine during lactation in the Bennett's wallaby (Macropus rufogriseus rufogriseus)
Authors: Curlewis J. D. , White A. S. , Loudon A. S. I. , McNeilly A. S. 
Published: December 2008

ABSTRACT
Prolactin concentration was measured in plasma collected each week for 13 months from lactating and non-lactating Bennett's wallabies (Macropus rufogriseus rufogriseus). In non-lactating animals, prolactin concentrations decreased towards the end of the study but such changes did not appear to fit a seasonal pattern. Prolactin concentrations were low during early lactation and at a similar level to non-lactating animals, increased significantly during late pouch life (February–May), and then returned to non-lactating levels at a time coincident with permanent exit of the joey from the pouch. Temporary removal of joeys from their mothers in April was followed by a rapid decline in prolactin concentrations which remained low for 24 h until the joey was returned to its mother, whereupon prolactin concentrations increased significantly within 2 h.
The effect of a single injection of bromocriptine (5 mg/kg) on lactation, embryonic diapause and plasma prolactin concentrations was examined at two stages of lactation. In November (lactational diapause), bromocriptine had no effect on prolactin concentrations but two out of four suckling joeys died on days 13 and 14 after treatment, and three out of four females gave birth on days 27, 27 and 28. Bromocriptine treatment in April (seasonal diapause) was followed by a significant reduction in prolactin concentrations and reduced growth rate of joeys belonging to treated females. New births were not observed.
In view of the effect of bromocriptine on plasma prolactin concentrations in late lactation and the demonstration that domperidone (a dopamine antagonist) significantly increases plasma prolactin concentrations, it would seem that dopamine can act as a prolactin inhibitory hormone in this as in other mammalian species.
J. Endocr. (1986) 110, 59–66
Differential potency of oestradiol-17β and diethylstilboestrol on separate groups of responses in the rat uterus
Authors: Grunert G. , Porcia M. , Tchernitchin A. N. 
Published: December 2008

ABSTRACT
The present study describes the effects of oestradiol-17β and diethylstilboestrol (DES) on several oestrogenic responses in the immature rat uterus Diethylstilboestrol was (1) weaker than oestradiol in inducing uterine eosinophilia, water imbibition and mitoses, (2) as strong as oestradiol in eliciting epithelial hypertrophy at 24 h after treatment, and (3) stronger than oestradiol in eliciting the reduction of epithelial cell height at 6 h after treatment and myometrial cell hypertrophy at 24 h after treatment. In addition, differences among the mitotic responses to oestrogen of the different uterine cell types were also detected. The above dissociation of the effects of DES and oestradiol-17β is in agreement with the hypothesis that eosinophil-mediated non-genomic responses, genomic responses and cell proliferation are mediated by independent mechanisms, involving different receptors which may have different affinities for both compounds. The eosinopenia and eosinophil degranulation under DES treatment suggest an explanation for the effect of DES on water imbibition. The dissociation among genomic responses from the different uterine cell types supports the hypothesis that different kinds of cytosol-nuclear oestrogen receptors exist.
J. Endocr. (1986) 110, 103–114
Ontogeny of prolactin receptors in rat decidual tissue: binding by a locally produced prolactin-like hormone
Authors: Jayatilak P. G. , Gibori G. 
Published: December 2008

ABSTRACT
The objectives of this investigation were to determine whether decidual tissue possesses specific binding sites for prolactin, and to examine whether the locally produced prolactin-like hormone binds to these receptors. Characterization of the binding of prolactin to decidual tissue from rats at day 9 of pseudopregnancy revealed specific, high-affinity sites. Binding approached saturation with increasing concentrations of either the ligand or the protein. Cytosolic extracts of day-9 decidual tissue, containing various amounts of decidual luteotrophin which possesses several of the physiological and biochemical characteristics of prolactin, displaced the binding of 125I-labelled prolactin to decidual membranes in a linear fashion. Prolactin-binding sites were detectable 72 h after induction of decidualization and 48 h after the appearance of decidual luteotrophin in the decidua. Prolactin receptor concentrations increased significantly between days 8 and 9, reached a plateau between days 9 and 12 and declined abruptly on days 14 and 15, accompanied by a similar decline in decidual luteotrophin concentration in the tissue. Thus rat decidual tissue possesses specific receptors for prolactin to which decidual luteotrophin locally produced can bind, thereby suggesting an auto/paracrine role for this substance.
J. Endocr. (1986) 110, 115–121
Superior cervical ganglionectomy prevents gonadal regression and increased plasma prolactin concentrations induced by long days in goats
Authors: Maeda K.-I. , Mori Y. , Kano Y. 
Published: December 2008

ABSTRACT
The effects of the abolition of the diurnal change in melatonin secretion on the photoperiodic response of the gonadal axis and prolactin secretion to long days were examined in female goats. Female Saanen goats, reared under short-day conditions (8 h light: 16 h darkness; lights on at 05.00 h) at 22±2 °C for 5 months, were bilaterally superior cervical ganglionectomized (SCGX). One month after surgery, both SCGX and intact control goats were divided into two groups. Animals in group 1 were maintained under short days and those in group 2 moved to long days (16 h light: 8 h darkness; lights on at 05.00 h). In group 1, both SCGX and intact goats ovulated periodically and basal plasma prolactin levels were maintained throughout the day. In intact controls, exposure to long days suppressed ovulation and increased prolactin secretion for the first 150–200 days of exposure. The animals became photorefractory after this time; ovulation recurred and prolactin secretion returned to basal levels. Superior cervical ganglionectomy abolished or weakened the suppression of gonadal function and eliminated the increase in prolactin secretion induced by exposure to long days in the intact controls.
These results suggest that the pattern of melatonin secretion under long days is necessary to induce the photoperiodic response of gonadal function and prolactin secretion to long days and that, under natural conditions, melatonin regulates the seasonal changes in gonadal function and prolactin secretion by mediating the effect of long days.
J. Endocr. (1986) 110, 137–144
Somatomedin C/insulin-like growth factor I: simplified purification procedure and biological activities of the purified growth factor
Authors: Morrell D. J. , Ray K. P. , Holder A. T. , Taylor A. M. , Blows J. A. , Hill D. J. , Wallis M. , Preece M. A. 
Published: December 2008

ABSTRACT
Human somatomedin C has been purified from Cohn fraction IV paste by a simplified procedure using chromatofocusing, hydroxylapatite chromatography and reverse-phase high performance chromatography. The purified material has a specific activity by somatomedin C radioimmunoassay of 9160 units/mg (1 unit is defined as the amount of somatomedin present in 1 ml normal adult male human serum), representing a 650 000-fold purification, and possesses sulphation, mitogenic and insulin-like activities (specific activities of 3388 units/mg, 832 units insulin equivalents/mg and 1122 units/mg respectively). Somatomedin C is shown to be a potent stimulator of DNA synthesis (50% maximum stimulation at 150 fmol/ml) in isolated chondrocytes derived from costal cartilage, a major physiological target tissue.
J. Endocr. (1986) 110, 151–158
Ultrastructural modifications provoked by tamoxifen either alone or combined with oestradiol in the uteri of fetal or newborn guinea-pigs
Authors: Pasqualini J. R. , Lecerf F. 
Published: December 2008

ABSTRACT
The ultrastructural changes in the uterine epithelial cells of fetal and newborn guinea-pigs were examined by transmission electron microscopy after the administration of tamoxifen, oestradiol or a combination of tamoxifen and oestradiol.
Tamoxifen provoked a substantial alteration of the mitochondria and the rough endoplasmic reticulum with the formation of numerous vacuoles and secretory granules, indicating an enhancement of synthetic and secretory activities. The mixture of oestradiol and tamoxifen increased the effect and most organelles became irreversibly altered, particularly in the uteri of newborn animals after a long treatment.
It is concluded that, in addition to the agonistic oestrogen effects of tamoxifen on uterine growth, DNA and protein contents, tamoxifen also acts as an agonist on the ultrastructural changes of the uterine epithelial cells during the perinatal period of the guinea-pig.
J. Endocr. (1986) 110, 197–202
Effects of iodide and thyroxine on iodine-deficient mouse thyroid: a morphological and functional study
Authors: Many M.-C. , Denef J.-F. , Hamudi S. , Cornette C. , Haumont S. , Beckers C. 
Published: December 2008

ABSTRACT
The effects of iodide and thyroxine (T4) on female mice fed a low iodine diet (LID) for 8 weeks were analysed by morphological, stereological and biochemical methods. Iodide was given at a dose of 10 μg/day (HID) or 1 μg/day (MID), either alone or together with daily injections of 1 μg T4 for 8 or 40 days.
With HID, the thyroid weight and the numbers of follicles and cells remained higher than in controls, although cell necrosis occurred. Colloid volume increased and iodine was stored within the gland: a colloid goitre with non-functioning follicles was produced. With MID, the glands resumed an almost normal appearance. With T4 and LID, progressive normalization occurred, but after 40 days thyroid weight and numbers of follicles and cells remained higher than in controls. Glandular iodine content slowly increased and reached control value. The proportions of 125I-labelled tri-iodothyronine (T3) and T4 in thyroglobulin were reduced. With T4 and HID, the glands resumed a normal appearance. Neither necrosis nor folliculoneogenesis was noted. The proportions of 125I-labelled T3 and T4 in thyroglobulin were reduced, but T3 and T4 serum levels were higher than with HID. With T4 and MID, a normal state was obtained as early as day 8. After 40 days the gland was morphologically and functionally inactive.
In conclusion, the association of T4 and iodide seems to be the best way to obtain a rapid and complete involution of thyroid hyperplasia. The administration of T4 prevents the deleterious effects of an excess of iodine on follicular cells, and causes the gland to enter a slow-functioning state.
J. Endocr. (1986) 110, 203–210
Effect of underfeeding on testosterone–LH feedback in the bull
Authors: Gauthier D. , Coulaud G. 
Published: December 2008

ABSTRACT
This study was conducted to investigate the hypothesis that the low LH pulsatility induced by underfeeding may result from an altered negative-feedback response to testosterone in cattle.
Eight 21-month-old Aubrac bulls were divided into two equal groups. The first group (group H) received a high level of nutrition (producing a gain in weight of 570 g/day) and the second group (group L) a low level of nutrition (producing a loss in weight of 330 g/day). After 52 days of underfeeding the bulls were hemicastrated, castrated 7 days later and then injected with 30 mg testosterone daily for 14 days, 10 mg daily for 7 days and 2·5 mg daily for 7 days.
After hemicastration, LH pulsatility was higher (P < 0·001) in group H (9·0 pulses in 24 h) than in group L (5·3 pulses in 24 h). After castration this value was the same in the two groups (24 pulses in 24 h). When the bulls were injected daily with 30 or 10 mg testosterone, the number of LH pulses in 24 h was lower (P < 0·05) in group L (14·3 and 9·8 pulses in 24 h with 30 mg, and 17·3 pulses in 24 h with 10 mg) than in group H (27·8 and 25·5 pulses in 24 h with 30 mg, and 24·0 pulses in 24 h with 10 mg). When the animals received 2·5 mg testosterone daily, the number of LH pulses was the same in both groups (20·3 pulses in 24 h).
These results indicate that the negative-feedback response of the LH-releasing system to testosterone is modified by underfeeding in the bull.
J. Endocr. (1986) 110, 233–238
Evidence for the presence of the pituitary insulin secretagogue β-cell trophin in human plasma
Authors: Salvatoni A. , Dunmore S. J. , Morton J. L. , Etienne A. T. , Beloff-Chain A. , Abraham R. R. 
Published: December 2008

ABSTRACT
It has been demonstrated that the insulin secretagogue β-cell-trophin, ACTH(22–39), is present in human plasma. The hormone, separated from plasma by affinity chromatography on a corticotrophin-like intermediate-lobe peptide antibody column, behaves similarly to synthetic β-cell-trophin on a gel filtration column and on reverse-phase high-performance liquid chromatography. Sufficient amounts of the hormone were isolated from the plasma of two patients with Nelson's syndrome to demonstrate its biological activity on the perfused rat pancreas.
J. Endocr. (1986) 110, 303–307
Stress-induced prolactin release in female, male and androgenized rats: influence of progesterone treatment
Authors: Jahn G. A. , Deis R. P. 
Published: December 2008

ABSTRACT
Ether stress applied at 10.00 h induced a 100% increase in serum prolactin in intact and ovariectomized androgenized rats. Ovariectomy significantly diminished the basal serum prolactin values observed in intact androgenized rats. Two doses of progesterone (5 mg) given to intact and ovariectomized androgenized rats 14 and 2 h before exposure to ether stress increased prolactin values in the control groups but completely prevented the effect of stress. Exposure to ether stress induced a 100% increase in serum prolactin values in androgenized rats with increased serum progesterone levels 4 days after the induction of ovulation and the luteal phase with human chorionic gonadotropin (hCG). A group of androgenized rats with induced maternal behaviour and which had been suckled for 6 days was given 100 i.u. hCG and suckled for another 6 days after the hCG-induced luteal phase had been established. The serum prolactin and progesterone values of these rats were significantly higher than those treated with hCG only and ether stress did not increase prolactin release. A greatly increased serum concentration of prolactin was obtained in pro-oestrous and oestrous virgin rats after exposure to ether stress. Serum prolactin was also increased by stress in male rats. Progesterone administration to these female and male rats prevented stress-induced prolactin release. To ascertain the part played by dopamine and serotonin in the effect of stress on prolactin release, groups of androgenized and oestrous female rats were treated with bromocriptine or p-chlorophenylalanine methylester hydrochloride (pCPA). The dopaminergic agonist bromocriptine markedly reduced prolactin levels in the unstressed androgenized rats, but did not prevent the prolactin increases induced by stress. Administration of pCPA had no effect on basal or stress-increased serum levels of prolactin. It is concluded that modifications of the ovarian steroid secretions, especially of progesterone, has profound effects on prolactin release in response to ether stress. The release of the hormone was not mediated by a dopaminergic or serotonergic regulatory pathway.
J. Endocr. (1986) 110, 423–428
Factors affecting prolactin secretion during the breeding cycle of the ring dove (Streptopelia risoria) and its possible role in incubation
Authors: Lea R. W. , Vowles D. M. , Dick H. R. 
Published: December 2008

ABSTRACT
Plasma prolactin began to increase significantly about 5 days after the onset of incubation in both sexes of the dove to reach a peak at the time of hatch. At this time, the concentration of prolactin in the plasma of the female was significantly higher than in the male. In the middle of the incubation period prolactin levels measured over a 24-h period remained constant in both sexes, although the male sits during the middle of the day and the female for the rest of the time. Nest deprivation resulted in a sharp, significant decline in the concentration of prolactin in both sexes. Newly hatched squabs stimulated the release of prolactin only in those doves which had been incubating eggs for several days.
A distinct sex difference was observed in the expression of nest defence behaviour of the ring dove during the breeding cycle. At the time of laying, the female was significantly more aggressive than the male and her aggression increased only slightly up to the time of hatching. In contrast, male aggression increased gradually from a low level at laying to reach a peak at the time of hatching. The levels of plasma progesterone in the female showed a significant increase around the time of lay. No significant changes occurred in the plasma concentration of either progesterone or 17α-hydroxyprogesterone in the male.
Administration of prolactin increased the length of time of incubation of infertile eggs. Nest manipulations which had the effect of inducing the doves to begin incubation 4 days before laying showed that (1) the length of time of incubation of infertile eggs is fixed and independent of events which occur at courtship or oviposition, (2) the initiation of the increase in plasma prolactin concentration during incubation is independent of events which occur at courtship and oviposition and (3) the termination of incubation is always preceded by a fall in the concentration of plasma prolactin.
It is concluded that the length of time of incubation is dependent upon sustained raised levels of plasma prolactin. The concentration of plasma prolactin increases several days after the onset of incubation in response to the tactile stimulation of sitting. High levels, if maintained by visual stimulation from the nest, maintain incubation for a fixed period. After this, if the eggs fail to hatch, prolactin levels fall and the doves cease incubation and begin a new cycle.
J. Endocr. (1986) 110, 447–458
Role of sodium influx in thyrotrophin action: effects of the sodium channel agonist veratridine and thyrotrophin on radioiodine turnover and membrane potential in cultured porcine thyroid cells
Authors: Manley S. W. , Huxham G. J. , Bourke J. R. 
Published: December 2008

ABSTRACT
Veratridine, a sodium channel agonist, depolarized cultured thyroid cells and increased the secretion of radioiodine from the organically bound pool. These effects were similar to those of TSH. Depolarization of the cells by increasing the potassium concentration of the medium failed to promote secretion, indicating that the sodium influx, rather than the depolarization itself, mediated the response. Veratridine, like TSH, also acutely reduced the cells' iodide uptake and inhibited the iodide transport pump. Unlike TSH, however, veratridine reduced, rather than increased, the fractional exit rate of iodide anion from the unbound pool. The data are consistent with the hypothesis that a sodium influx mediates some but not all of the actions of TSH on the thyroid gland, including the stimulation of secretion of thyroid hormones.
J. Endocr. (1986) 110, 459–466
Minimal effects of 17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (R1881) on sexual behaviour in prepubertally castrated rams
Authors: Parrott R. F. 
Published: December 2008

ABSTRACT
Ten adult prepubertally castrated rams were injected with 5α-dihydrotestosterone propionate (DHTP; 20 mg/day) for 3 weeks to stimulate genital development. Thereafter, half of the sheep were injected with testosterone (100 mg/day) for a further 4 weeks, while the remainder received the same dose of 17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (methyltrienolone; R1881). All the animals were tested for sexual behaviour on 15 occasions with ovariectomized ewes in which oestrous behaviour was induced by injections of 50 μg oestradiol-17β benzoate at 4- to 5-day intervals. Behavioural tests were of 10 min duration and were carried out thrice weekly over a 5-week period, starting in the final week of DHTP treatment. Animals treated with testosterone showed a highly significant increase in courtship behaviour (tongue-flicks; lunges and nudges) after only four daily injections and this level of activity was maintained to the end of the experiment. However, the incidence of courtship activity in sheep treated with R1881 was similar to that recorded during the period of DHTP treatment. All animals given testosterone displayed mounts with pelvic thrusts and erections, and achieved intromission with ejaculation. These activities remained significantly more frequent than in sheep treated with R1881, starting from tests 9, 8 and 12 respectively. Four of the five individuals in the group given R1881 showed occasional mounts with thrusts, three showed sporadic erections and one sheep intromitted in the final test. These results indicate that, in contrast to the rat, R1881 has only very weak effects on sexual behaviour in the castrated ram.
J. Endocr. (1986) 110, 481–487
Social behaviour and testicular activity of juvenile rats
Authors: Taylor G. T. , Frechmann T. , Royalty J. 
Published: December 2008

ABSTRACT
The juvenile stage of ontogeny is often characterized as a time of inactivity and quiescence for the immature reproductive system. The principle social behaviour by juveniles of many mammalian species is a rough-and-tumble activity known as play-fighting. An experiment is reported in which play-fighting by male rats was observed after various manipulations of gonadal steroids. Rats were housed in groups and castrated either on day 1 or day 10, times which are respectively during and after the sensitive period for androgeninduced organization of neural tissues in rats. Animals were injected with either 40 μg testosterone propionate or vehicle between 21 and 45 days of age, and play-fighting with unoperated, unfamiliar rats was examined. Castration on days 1 and 10 suppressed play-fighting. The behaviours remained suppressed in rats castrated on day 1 and injected with testosterone propionate, but testosterone propionate restored play-fighting to near-normal levels until 35 days of age in rats castrated on day 10. Moreover, gonadally intact juvenile males exposed to the androgen antagonist flutamide play-fought less than intact control males, although their social activity increased appreciably after day 35. It is concluded that the juvenile is not experiencing endocrine quiescence. Behavioural and physiological data suggest a reproductive system which is active, although differently from that in the adult. Hypersensitivity to testosterone and surges of gonadotrophin-releasing factors and LH at 35 days of age may be the events responsible for changes in play-fighting resulting from manipulations of gonadal steroids in juvenile rats.
J. Endocr. (1986) 110, 533–537