bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental manipulations of prolactin following removal of pouch young or bromocriptine treatment during lactational quiescence in the Bennett's wallaby
Authors: Curlewis J. D. , Loudon A. S. I. 
Published: December 2008

ABSTRACT
Experiments were conducted to investigate whether prolactin suppresses the corpus luteum during lactational quiescence in the Bennett's wallaby. In the first experiment, pouch young were removed from lactating wallabies (day 0) which were then treated daily for 7 days with either saline, or 8 mg domperidone or 2 mg ovine prolactin. In the saline-injected animals there was a transient peak in progesterone concentrations on day 4 and birth on day 28. The transient progesterone peak and births were significantly (P <0·01) delayed by 5 and 8 days in animals treated with domperidone and ovine prolactin respectively. In the second experiment, four groups of lactating wallabies were treated on day 0 with either 60 mg bromocriptine (groups C and D) or the vehicle (groups A and B). On days 0–6, groups B and D were injected daily with 2 mg ovine prolactin while groups A and C received the vehicle. In group C, three pouch young died 14–29 days after administration of bromocriptine, and there was a transient rise in progesterone on day 4 in all animals, indicating that bromocriptine resulted in immediate reactivation of the quiescent corpus luteum. New births occurred in two animals on day 28. In group D, which received bromocriptine followed by ovine prolactin for 7 days, all the original pouch young remained alive at the end of the experiment. Four of the animals from this group showed a transient progesterone peak on day 11, with births in two animals on days 35 and 36 indicating that the effects of bromocriptine were prevented whilst ovine prolactin was being administered. In one animal given ovine prolactin alone (group B), there was a transient progesterone peak and birth on days 12 and 35 respectively, suggesting that removal of exogenous prolactin may also act to terminate reproductive quiescence in some animals. In summary, these results support the hypothesis that prolactin suppresses the corpus luteum during lactational quiescence, and that the effects of bromocriptine are due to suppression of endogenous prolactin.
J. Endocr. (1988) 119, 405–411
Effects of chronic long-acting bromocriptine treatment on liveweight, voluntary food intake, coat growth and breeding season in non-pregnant red deer hinds
Authors: Curlewis J. D. , Loudon A. S. I. , Milne J. A. , McNeilly A. S. 
Published: December 2008

ABSTRACT
Seventeen red deer hinds were housed in individual pens and from 28 February until 11 November were injected each week with vehicle (group A; n = 6) or 5 (group B; n = 6) or 12·5 mg (group C; n = 5) of a long-acting formulation of bromocriptine. Liveweight and voluntary food intake (VFI) were recorded for each hind, and blood was collected for determination of progesterone, prolactin, tri-iodothyronine (T3) and cortisol concentrations by radioimmunoassay. Treatment with the high dose of bromocriptine was associated with a significant (P <0·05) reduction in VFI, with the effect being greatest between March and July. There was no treatment effect on liveweight, but there was a significant (P <0·01) interaction between time and treatment due to the faster rate of weight gain in control animals at the beginning of the experiment. Changes in liveweight could be explained by changes in VFI rather than by changes in the efficiency of utilization of intake. Termination of the breeding season was significantly (P <0·01) delayed by 54 days in group C hinds. Growth of the summer coat and subsequent winter coats was delayed by 1 and 3 months respectively in group C hinds, and in groups B and C the duration that animals were in summer coat was increased by about 1 month. The seasonal increase in prolactin concentrations was seen in all groups, but levels were significantly (P <0·05) lower in group C hinds. Concentrations of T3 and cortisol were not affected by bromocriptine.
J. Endocr. (1988) 119, 413–420
Conformational transition of thyroid hormone receptor upon hormone binding: demonstration by aqueous two-phase partitioning
Authors: Ichikawa K. , Hashizume K. , Miyamoto T. , Nishii Y. , Yamauchi K. , Ohtsuka H. , Yamada T. 
Published: December 2008

ABSTRACT
An aqueous two-phase partitioning study of partially purified nuclear thyroid hormone receptor from rat liver was performed. Stability of 3,5,3′-tri-iodo-l-thyronine (T3)–receptor complex and T3-binding activity in the presence of dextran or polyethylene glycol were assessed in order to determine the amount of occupied or unoccupied receptors in each phase. Partition coefficients were calculated as the ratio of receptor concentration in the upper polyethylene glycol-rich phase H2O and that in the lower dextranrich phase H2O. The partition coefficient was a sensitive function of the salt at pH above 6·1 and below 5·1. The salt had no effect on the partition coefficient at pH around 5·6. These results suggest that the isoelectric point of the thyroid hormone receptor is about 5·6, confirming previous determinations using isoelectric focusing. The partition coefficient of the receptor decreased upon T3 binding, regardless of the salt composition. In contrast, the partition coefficient of thyroxine-binding globulin increased upon T3 binding. Free T3 preferentially partitioned into the upper polyethylene glycol-rich phase and gave a partition coefficient higher than 1·0. These results strongly suggest that the decrease in the partition coefficient of the receptor upon hormone binding reflects conformational changes or changes in electrostatic properties of the receptor upon hormone binding. Such an alteration may be involved in biological activation of the receptor upon hormone binding.
J. Endocr. (1988) 119, 431–437
Accelerated recovery of Leydig cells of the immature rat testis after administration of the cytotoxic ethylene dimethanesulphonate
Authors: Edwards G. , Lendon R. G. , Morris I. D. 
Published: December 2008

ABSTRACT
A single injection of ethane-1,2-dimethanesulphonate (EDS; 100 mg/kg) selectively destroys Leydig cells in the testis of the adult rat; however, unconfirmed reports indicate that Leydig cells in the immature rat are not affected. In this study the effect of EDS was examined 2 days after treatment of rats aged 20, 25 or 35 days. There was a large reduction in the in-vitro binding of 125I-labelled human chorionic gonadotrophin (hCG) to the homogenates of testes from EDS-treated immature rats. EDS reduced the testosterone content of the testes at all ages studied, but 2 days after injection had only significantly lowered the serum testosterone concentration of 25- or 35-day-old animals. Light microscopic examination of the testis of the 22-day-old rat, 2 days after treatment with EDS, indicated that there were still many cells staining for 3β-hydroxysteroid dehydrogenase. The interstitium also contained numerous atypical cells which did not stain for 3β-hydroxysteroid dehydrogenase. Electron microscopy of testes from the 22-day-old EDS-treated rat showed that Leydig cells were still present in the interstitium together with macrophages and fibroblast-like cells. Six days after EDS treatment of 20-day-old rats, but not 35-day-old rats, there was an increase in the binding of 125I-labelled hCG to testis homogenate to 70% of control value. Testicular testosterone content 6 days after treatment of the 20-day-old rat had risen to 50% of the control testis value. These changes documented in the 20-day-old rat after EDS treatment can be explained by either a cytocidal effect with subsequent repopulation of new Leydig cells which has been described in the adult rat or by a reversible cytotoxic action which has not previously been documented.
J. Endocr. (1988) 119, 475–482
Insulin-like growth factor-I and its association with binding proteins in bovine milk
Authors: Campbell P. G. , Baumrucker C. R. 
Published: December 2008

ABSTRACT
Immunoreactive insulin-like growth factor-I (IGF-I) in bovine milk was quantified. IGF-I was principally association with an ∼45 kDa binding protein. In addition, a small fraction of IGF-I occurred at a molecular weight approximately the same as that of unbound IGF-I. Available binding sites existed on the ∼45 kDa binding protein. Bound IGF-I was readily dissociated from binding protein by acid treatment. When IGF-I was estimated in milk obtained from primiparous and multiparous cows, multiparous cows had a higher concentration (40 μmol/l) at parturition than primiparous cows (19·2 μmol/l). By day 2 of lactation, IGF-I concentrations were 30 and 50% of initial estimates for multiparous and primiparous cows respectively. The final IGF-I concentration, on day 56 of lactation, was 4·5 μmol/l for combined parity groups. At parturition in multiparous cows, the mass of IGF-I was estimated at 183 and 157 μmol for blood and milk pools respectively. Milk, therefore, represents a substantial pool of IGF-I in the cow. The mechanism of the appearance of IGF-I in bovine milk is unknown.
Journal of Endocrinology (1989) 120, 21–29
Endometrial responses to a deciduogenic stimulus in ovariectomized rhesus monkeys treated with oestrogen and progesterone
Authors: Ghosh D. , Sengupta J. 
Published: December 2008

ABSTRACT
To establish an artificial model for the study of decidual cell reaction in the rhesus monkey, long-term ovariectomized animals were treated with oestrogen followed by progesterone and an artificial deciduogenic stimulus was applied on day 16 of the treatment cycle. Histological examinations of the endometrial samples on different days following stimulation showed prominent epithelial plaque reaction by day 20. Marked subepithelial oedema surrounding plaque cells was also noted. On day 32, degenerating plaque cells with leucocytic infiltration were found. Beginning on day 24 of hormone treatment, stromal fibroblasts adjacent to plaque and glands showed swelling with rounding-up and enlargement of nuclei; these stromal cells appeared more decidual-like with moderate amounts of hypertrophy and few were binucleate by day 28. Endometrial granular cells became more conspicuous and appeared to increase in numbers adjacent to glands and blood vessels. Endometrial glands showed no notable changes, and were mostly tortuous with columnar epithelium and apocrine-type secretions. Around days 40 and 48 of the treatment cycle, the luminal margins of the glands became bosselated, and significant amounts of secretion were present in the glandular lumen. Measurement of immunoreactive concentrations of oestradiol-17β and progesterone in endometria from traumatized, hormone-treated monkeys revealed significant (P < 0·01) decreases in levels of oestradiol with time while the level of progesterone remained unchanged (P > 0·02). The corresponding profiles of concentrations of nuclear receptors for oestrogen and progesterone reflected the status of ligand availability in the endometrium; nuclear levels of progesterone receptors were maintained but significant decreases in cytoplasmic progesterone receptors (P < 0·03) and nuclear oestrogen receptors (P < 0·05) were evident with the period of treatment.
Journal of Endocrinology (1989) 120, 51–58
Effects of immunization against recombinant bovine inhibin α subunit on circulating concentrations of gonadotrophins in ewes
Authors: Findlay J. K. , Doughton B. , Robertson D. M. , Forage R. G. 
Published: December 2008

ABSTRACT
Immunization of ewes against a pure recombinant preparation of the α subunit of bovine inhibin (α-bI) resulted in a three- to fourfold increase in ovulation rate, associated with antibodies in plasma recognizing pure native 31 kDa inhibin. The aim of this study was to examine the effects of this immunization on basal and GnRH-stimulated plasma concentrations of FSH and LH in ewes during the anoestrous and breeding seasons. The groups were untreated control ewes (n = 5), control ewes treated with keyhole limpet haemocyanin (KLH alone, n = 4), ewes treated with α-bI alone (n = 4) and α-bI–KLH conjugate-treated ewes (n = 3). There were no effects of immunization on basal FSH or LH in anoestrous ewes, despite the presence of antibodies recognizing 31 kDa inhibin. In the breeding season, immunization against α-bI resulted in increased basal (follicular phase, P < 0·1; luteal phase P < 0·05) and GnRH-stimulated (follicular phase only, P < 0·001) release of FSH, but not LH. The data are compatible with the hypotheses that the increase in ovulation rate in immunized ewes is due to an increase in circulating FSH concentrations and that inhibin may only have a major peripheral influence on FSH in sheep during the breeding season.
Journal of Endocrinology (1989) 120, 59–65
Effects of pure FSH and LH preparations on the number and function of Leydig cells in immature hypophysectomized rats
Authors: Teerds K. J. , Closset J. , Rommerts F. F. G. , de Rooij D. G. , Stocco D. M. , Colenbrander B. , Wensing C. J. G. , Hennen G. 
Published: December 2008

ABSTRACT
The effects of pure FSH and/or LH preparations on the number of Leydig cells and their function in immature hypophysectomized rats have been investigated. As a result of hypophysectomy at the age of 17–18 days, the number of recognizable Leydig cells per testis decreased, as did the steroidogenic capacity in vivo and in vitro. Treatment with 64 μg FSH on both 22 and 23 days of age, did not affect the number of recognizable Leydig cells. In contrast, two injections of LH (10 μg) caused a sixfold increase in the number of Leydig cells, but had a negative effect on spermatogenesis. These stimulatory and inhibitory effects of LH diminished when FSH was added. Treatment with FSH for 7 days caused a twofold increase in the number of Leydig cells when compared with hypophysectomized controls. 3β-Hydroxysteroid dehydrogenase (3β-HSD) and esterase activity in Leydig cells also increased under the influence of FSH. The pregnenolone production per Leydig cell in the presence of 5-cholesten-3β,22(R)-diol (22R-hydroxycholesterol) as substrate showed a sevenfold increase. Plasma testosterone levels 2 h after injection of human chorionic gonadotrophin in intact rats and hypophysectomized FSH-treated rats were the same. Following LH treatment for 7 days, the number of Leydig cells proved to be 11 times higher, and 3β-HSD and esterase activity were not different from intact controls. The testicular pregnenolone production was four- to fivefold higher when compared with untreated hypophysectomized rats. However, pregnenolone production per Leydig cell in LH-treated rats was only slightly different from the hypophysectomized controls.
In conclusion, FSH treatment caused an increase in the number and steroidogenic activity of Leydig cells, and LH had a major effect on the number of Leydig cells, but did not stimulate the steroidogenic capacity.
Journal of Endocrinology (1989) 120, 97–106
Long-term negative feedback effects of oestrogen and progesterone on the pituitary gland of the long-term ovariectomized ewe
Authors: Clarke I. J. , Cummins J. T. , Crowder M. E. , Nett T. M. 
Published: December 2008

ABSTRACT
The effects of long-term treatment with physiological doses of oestradiol or oestradiol plus progesterone on plasma gonadotrophin levels and pituitary content of LH and gonadotrophin-releasing hormone (GnRH) receptors were studied in ovariectomized–hypothalamo-pituitary disconnected ewes given 250 ng pulses of GnRH every 2 h (i.v.). A pilot experiment showed that 3 cm long Silastic implants (s.c.) reduced both LH pulse frequency and pulse amplitude in long-term (> 6 months) ovariectomized ewes. The main experiment was conducted over 3 weeks in ovariectomized–hypothalamo-pituitary disconnected ewes that had received pulsatile GnRH replacement for 1 week after pituitary surgery. Group 1 (n = 5) received GnRH pulses alone throughout the study. Group 2 (n = 6) received oestradiol in week 2 and oestradiol plus progesterone in week 3 and in group 3 (n = 6) the steroid treatments were reversed. Oestradiol reduced (P < 0·05) the mean (± s.e.m.) amplitude of LH in pulses in group 2 (from 8·2 ± 1·6 to 5·0 ± 0·5 μg/l) and group 3 (from 11·6 ± 1·2 to 9·3 ±1·0 μg/l); an additional effect of progesterone was seen in group 2 but not group 3. The amplitudes of the LH pulses did not change in the control ewes. Plasma concentrations of FSH were reduced by approximately 50% by the oestradiol treatments with no additional effects of progesterone. There was no effect of steroidal treatment on pituitary content of LH or pituitary levels of GnRH receptors.
We conclude that long-term oestradiol treatment, with or without progesterone, reduces plasma amplitudes of LH pulses by a direct pituitary effect, but the magnitude of this effect was less than that observed on GnRH secretion in short-term ovariectomized ewes in an earlier study. The reduction in plasma LH pulse amplitude is not due to a direct pituitary effect of these steroids on GnRH receptor number.
Journal of Endocrinology (1989) 120, 207–214
Atrial natriuretic peptide and sodium nitroprusside stimulate cyclic GMP accumulation by avian skin fibroblasts and epiphyseal growth-plate chondroprogenitor cells
Authors: Pines M. , Hurwitz S. 
Published: December 2008

ABSTRACT
Chondroprogenitor cells derived from avian tibia epiphyseal growth plate, and skin fibroblasts were cultured in vitro. In the fibroblasts, human (1–28) and rat (5–28) atrial natriuretic peptide (ANP) stimulated cyclic GMP (cGMP) production in a dose-dependent manner without affecting cAMP. Sodium nitroprusside also stimulated cGMP accumulation by chondroprogenitor cells and fibroblasts, but the maximum cGMP accumulation elicited by sodium nitroprusside was much lower than that obtained with ANP. The effects of ANP and sodium nitroprusside on chondroprogenitor cells and skin fibroblasts were additive. Human ANP increased cGMP production by the particulate fraction prepared either from chondroprogenitor cells or fibroblasts. Sodium nitroprusside, at concentrations of up to 1 mmol/l, did not affect cGMP production by the particulate fraction prepared from either cell type.
The present study provides additional evidence that avian growth-plate chondroprogenitor cells and skin fibroblasts are targets for ANP. ANP and nitroprusside activate different guanylate cyclase isoenzymes – the particulate and soluble forms of the enzyme respectively. The data suggest that most of the guanylate cyclase activity in these cells is localized in the particulate fraction.
Journal of Endocrinology (1989) 120, 319–324
Histamine, mast cells and ovarian function
Authors: Krishna A. , Beesley K. , Terranova P. F. 
Published: December 2008

ABSTRACT
Mast cells, endothelial cells, basophils and platelets are potential sources of histamine in the ovary. Little is known about the role of the latter three cell types in ovarian function. Several studies have revealed changes in the number and degranulation (release of histamine) of mast cells in the ovary during the cycle. Mast cells degranulate on pro-oestrus in the rodent ovary, and mast cells numbers increase in the theca externa of the dominant follicle in the bovine ovary. In rodents, mast cells are limited to the ovarian hilum and are not observed in follicles, corpora lutea and interstitium; this contrasts with larger species such as man, cows and monkeys where mast cells are observed throughout the ovary. Evidence is accumulating that mast cell degranulation in the ovary may be regulated by neuronal input. Neurones have been shown to have close morphological relationships with mast cells in the ovary. Histamine participates in regulating capillary permeability and blood flow in the ovary. These actions are induced by injections of LH, yet the mechanism by which LH induces mast cell degranulation is unknown. Histamine stimulates ovarian contractility, ovulation and follicular progesterone secretion in vitro. Whether these actions of histamine occur in vivo are currently unknown. This review gives a chronological description of the discoveries of the effects of histamine on ovarian function and makes suggestions for future research in this area.
Journal of Endocrinology (1989) 120, 363–371
Properly timed injections of cortisol and prolactin produce long-term reductions in obesity, hyperinsulinaemia and insulin resistance in the Syrian hamster (Mesocricetus auratus)
Authors: Cincotta A. H. , Wilson J. M. , deSouza C. J. , Meier A. H. 
Published: December 2008

ABSTRACT
Naturally obese female Syrian hamsters were injected daily with prolactin at 0 or 12 h after cortisol injections for 10 days while held in constant light. Controls were similarly injected with saline. Animals were then held on short daylengths (10 h light:14 h darkness) for 10 weeks. They were allowed free access to food and water from birth to time of death. Ten weeks after treatment, retroperitoneal fat stores, plasma concentrations of insulin and glucose, and hypoglycaemic responsiveness to exogenous insulin were determined. The control groups as well as the 12-h hormone treatment group were obese, hyperinsulinaemic and insulin resistant. However, the 0-h treatment dramatically reduced retroperitoneal fat stores (41–55%), plasma insulin concentration (60–70%) and the insulin to glucose ratio (63–68%) compared with controls. Values for these parameters in the 0-h treatment groups were similar to those of their lean litter-mates. Furthermore, the 0-h group but not the 12-h group was more sensitive than control animals to the hypoglycaemic effects of exogenous insulin at doses 0·2 and 2·0 U/kg body weight. These results demonstrate that timed daily injections of cortisol and prolactin in specific temporal relationships can produce marked reductions in obesity, hyperinsulinaemia and insulin resistance in the Syrian hamster that persist long after the termination of treatment. This study also suggests an important role for the interactions of circadian neuroendocrine systems in the regulation of these metabolic states.
Journal of Endocrinology (1989) 120, 385–391
Expression of human or bovine growth hormone gene with a mouse metallothionein-1 promoter in transgenic swine alters the secretion of porcine growth hormone and insulin-like growth factor-I
Authors: Miller K. F. , Bolt D. J. , Pursel V. G. , Hammer R. E. , Pinkert C. A. , Palmiter R. D. , Brinster R. L. 
Published: December 2008

ABSTRACT
Endocrine profiles were examined in swine that had integrated and expressed a fusion gene consisting of mouse metallothionein-1 (MT) promoter fused to either a human (h) or bovine (b) GH structural gene. Eleven of 18 pigs that had integrated MT-hGH and eight of nine pigs that had integrated MT-bGH expressed the genes. The level of expression varied widely among pigs (14–4551 μg/l for MT-hGH and 23–1578 μg/l for MT-bGH). The level of expression varied over time within each pig with no general pattern. Concentrations of porcine GH (pGH) were lower in MT-hGH pigs that expressed the gene than in non-expressors or in littermate controls. Insulin-like growth factor-I (IGF-I) concentrations increased with age in all pigs and were raised threefold in pigs expressing either the MT-hGH or MT-bGH genes. Measurement of the foreign GH in samples taken at 15-min intervals failed to reveal any short-term fluctuations in concentration. Administration of hGH releasing factor (GRF) to pigs expressing MT-bGH resulted in attenuated release of pGH compared with that of contemporary controls. Concentrations of bGH did not change after GRF injection. Human and bovine GH expressed in transgenic pigs appear to be biologically active in that they induce IGF-I and suppress endogenous pGH secretion. The failure to find short-term fluctuations and the lack of response to GRF injections are consistent with a non-pituitary and non-GRF regulatable site of production.
Journal of Endocrinology (1989) 120, 481–488