bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gonadotrophin surge-attenuating factor attenuates in-vitro LH secretion induced by gonadotrophin-releasing hormone from cultured ovine pituitary cells only during the breeding season
Authors: Fowler P. A. , Townsend C. , Messinis I. E. , Cunningham P. , Templeton A. 
Published: December 2008

ABSTRACT
Primary cultures of ovine pituitaries from adult ewes were used to investigate aspects of gonadotrophin surge-attenuating factor (GnSAF) bioactivity in human follicular fluid (hFF) from superovulated women. During the autumn and first half of the winter, LH secretion induced by gonadotrophinreleasing hormone (GnRH) was markedly reduced (43·5 ± 5·2% of control GnRH-induced LH secretion) by incubation for 48 h with steroid-free hFF. For the rest of the year, treatment with the same batch of steroid-free hFF resulted in non-significant reduction or stimulation of GnRH-induced LH secretion (71·3± 13·2 to 117·8±11·2% of control GnRH-induced LH secretion). Incubation of pituitary cells for 48 h with oestradiol (1 pmol/l to 1 μmol/l), progesterone (1 pmol/l to 1 μmol/l) or oestradiol and progesterone combined (1 pmol/l to 1 μmol/l) in a two-way titration for 48 h had no significant effect on GnRH-induced LH secretion (83·4±7·6 to 110·6±5·0% of control secretion). Separating hFF into fractions of different molecular mass by ultrafiltration demonstrated that GnSAF bioactivity was present in a form 10–30 kDa in size. Incubation for 48 h with these fractions had no significant effect on basal FSH secretion but significantly attenuated GnRH-induced LH secretion during the autumn. The same fractions had little effect on GnRH-induced LH secretion from pituitary cells collected during the summer. We conclude that ovine pituitaries display at least partial reduction in sensitivity to GnSAF outside the breeding season. In addition, neither oestradiol nor progesterone singly or in combination caused the observed attenuation of GnRH-induced LH secretion that is ascribed to GnSAF bioactivity.
Journal of Endocrinology (1992) 135, 221–227
The role of thromboxane in the uterotrophic response in the gravid normotensive and spontaneously hypertensive rat
Authors: Kerr M. B. , Marshall K. , Senior J. 
Published: December 2008

ABSTRACT
The role of thromboxane in the gravid normotensive (CD) and hypertensive (SHR) rat was investigated (by utilizing two thromboxane receptor-blocking drugs, EP092 and AH23848) both at mid-gestation and at term. The parameters examined were uterine blood flow (blood flows were measured by the microsphere technique) and uterine weight and placental blood flow at term, fetal mass and number.
At mid-gestation EP092 significantly (P< 0·005) increased uterine blood flow in both strains whilst the increases seen with AH23848 were not statistically significant. At term (day 22 in the CD and day 23 in the SHR rat) the antagonists increased uterine blood flow in the CD rats alone. However, at this time the antagonists caused an increase in placental blood flow in both strains.
Thromboxane appears to be involved in the regulation of uteroplacental blood flow. The observation that the antagonists were able to potentiate blood flow by mid-gestation may provide a clinical indication with respect to potential prophylactic use of this class of compounds in cases of pregnancy-induced hypertension in women.
Journal of Endocrinology (1992) 135, 257–261
Passive immunization against circulating insulin-like growth factor-I (IGF-I) increases protein catabolism in lambs: evidence for a physiological role for circulating IGF-I
Authors: Koea J. B. , Gallaher B. W. , Breier B. H. , Douglas R. G. , Hodgkinson S. , Shaw J. H. F. , Gluckman P. D. 
Published: December 2008

ABSTRACT
Primed constant infusions of [14C]urea were used to determine the acute effect of passive immunization against circulating free and protein-bound insulin-like growth factor-I (IGF-I) on the rate of net protein catabolism (NPC) in castrated male lambs fasted for 48 h. Following an intravenous bolus of 50 ml IGF-I antiserum, the rate of NPC increased to a peak 30 min after injection of 1·69 ± 0·16 g/kg per day from a baseline value of 1·45±0·22 g/kg per day (P<0·05, n = 4). In three animals given 50 ml equivalents of the purified immunoglobulin fraction, NPC increased from 1·31 ±0·20 to 1·59±0·16 g/kg per day (P<0·05). A similar trend was observed in animals given 25 ml antiserum (n = 4). The rate of NPC did not increase following a bolus of non-immune serum in control animals and the rate of NPC in the treated lambs returned to control levels within 60 min of antibody injection. Plasma insulin and glucose concentrations in both the treated and control groups were unchanged throughout the study. These data suggest that circulating IGF-I has a physiological role in regulating whole body protein turnover during starvation and possibly other catabolic states. The effect of immunoneutralization of circulating IGF-I is transient and this suggests that while IGF-I has an endocrine role in the regulation of protein turnover, other regulatory mechanisms are involved.
Journal of Endocrinology (1992) 135, 279–284
Immunochemical detection of the major vitelline envelope proteins in the plasma and oocytes of the maturing female rainbow trout, Oncorhynchus mykiss
Authors: Hyllner S. J. , Haux C. 
Published: December 2008

ABSTRACT
The major vitelline envelope proteins were detected in the plasma of female rainbow trout maturing under natural conditions by using the Western blot technique. Females were sampled every month from July until ovulation in January. The amount of vitelline envelope proteins in plasma increased markedly as the gonads increased in size from 0·4 to about 15% of the total body weight. The plasma level of oestradiol-17β largely followed the alterations in the amount of vitelline envelope proteins, indicating the endocrine control of vitelline envelope protein synthesis. In addition, plasma vitellogenin changed in a manner that resembled the changes in the amount of plasma vitelline envelope proteins. The appearance and growth of the vitelline envelope during oocyte development was demonstrated using immunohistochemical methods. The vitelline envelopes from oocytes at different stages of development were immunoreactive with the antibodies directed against the major vitelline envelope proteins. No immunoreactivity could be observed in the ooplasm or in the surrounding follicular cells, which indicated that the major vitelline envelope proteins were of extraovarian origin. The present study further supports the hypothesis that the major protein constituents of the vitelline envelope in teleosts are under the endocrine control of oestradiol17β and that the site of synthesis is outside the ovary.
Journal of Endocrinology (1992) 135, 303–309
Activation of phospholipase A2 and phospholipase C by endothelin-1 in human endometrium
Authors: Ahmed A. , Cameron I. T. , Ferriani R. A. , Smith S. K. 
Published: December 2008

ABSTRACT
Human endometrium contains specific binding sites for iodinated endothelin (ET)-1, ET-2 and ET-3, and ET-1 stimulates prostaglandin (PG) F2α synthesis from explants of proliferative endometrium in short-term culture. This study has investigated the cellular responses of normal proliferative endometrium to ET-1. Radioimmunoassay was used to measure PG release and Dowex anion-exchange column chromatography was utilized to assess the accumulation of inositol phosphates. Endothelin-1 induced a significant increase in PGF2α release (basal median: 1465 pg/mg per 60 min (range: 541–3935 pg/mg per 60 min); ET-1-stimulated: 1813 pg/mg per 60 min (1021–5714 pg/mg per 60 min); P < 0·04 using Wilcoxon signed rank test). The effect of ET-1 was attenuated in the presence of the phospholipase A2 inhibitor quinacrine. Endothelin-1 induced a rapid, transient and concentration-dependent hydrolysis of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), measured by the accumulation of tritiated inositol phosphates. Following a 1-min stimulation with ET-1 (100 nmol/l), [3H]inositol mono-, bisand trisphosphate fractions increased from median values of 490·0 d.p.m./mg dry wt (range: 348·0–807·0 d.p.m./mg dry wt), 120·0 d.p.m./mg dry wt (93·6–144·1 d.p.m./mg dry wt) and 67·0 d.p.m./mg dry wt (54·2–85·0 d.p.m./mg dry wt) to 939·0 d.p.m./mg dry wt (635·9–1596·0 d.p.m./mg dry wt; P < 0·03), 145·0 d.p.m./mg dry wt (127·0–293·9 d.p.m./mg dry wt; P < 0·05) and 146·0 d.p.m./mg dry wt (77·5–187·0 d.p.m./mg dry wt; P < 0·03) respectively. These results suggest that ET-1 activates the phospholipase A2 and PtdIns(4,5)P2-specific phospholipase C in human proliferative endometrium, resulting in the generation of PGF2α and second messengers respectively which are pivotal to endometrial function.
Journal of Endocrinology (1992) 135, 383–390
Plasma atrial natriuretic peptide in vasopressin deficiency the effects of acute water deprivation in rats
Authors: Burgess W. J. , Balment R. J. 
Published: December 2008

ABSTRACT
Plasma concentrations of atrial natriuretic peptide (ANP) and other renally active hormones were measured in Long–Evans (LE) rats and vasopressin-deficient Brattleboro rats with diabetes insipidus (DI) in conditions of water repletion and deprivation, and in DI rats following chronic vasopressin replacement.
In water-replete rats, vasopressin deficiency was associated with elevated circulating ANP and angiotensin II (AII) concentrations, while plasma adrenal steroid concentrations were depressed by comparison with LE rats. These differences were fully reversed after 7 days of vasopressin replacement in DI rats to restore normal water turnover.
Water deprivation for 4 h had little effect on plasma tonicity or hormone profile in LE rats. In contrast, however, the unreplaced fluid loss during 4-h water deprivation in the DI rat was associated with a marked increase in plasma tonicity evident within 30 min. Plasma ANP concentrations fell substantially to levels below those in LE rats, coincident with a rise in adrenal steroid levels and independent of any clear change in AII. These changes in circulating ANP concentration were directly correlated with changes in plasma Na+ concentration, osmolality and tissue water content in the DI rats, underlining the importance of body fluid status in modulating the secretion of ANP.
These data clearly show that plasma ANP concentration is increased in vasopressin deficiency, but emphasize the sensitivity of circulating hormone levels in vasopressin-deficient animals to acute changes in the state of hydration, underscoring the complex and labile interaction between body fluid and hormonal factors involved in the control of ANP secretion.
Journal of Endocrinology (1992) 135, 431–438
Growth hormone (GH)-binding protein in normal and GH-deficient dwarf rats
Authors: Carmignac D. F. , Wells T. , Carlsson L. M. S. , Clark R. G. , Robinson I. C. A. F. 
Published: December 2008

ABSTRACT
There are GH-binding proteins (GHBPs) present in the blood of many species, and these correspond to the extracellular GH-binding domain of the GH receptor. In the rat, GHBP arises by alternative splicing of the GH receptor mRNA, but little is known of the physiological role of circulating GHBP, or its relationship with episodic GH secretion. We have developed a sensitive radioimmunoassay based on recombinant GHBP, and have measured rat GHBP levels in small samples of plasma from normal and GH-deficient dwarf rats. In normal adult rats, GHBP levels were two- to threefold higher in females than in males (16·6 ± 0·8 vs 6·4 ± 0·4μg/l, P < 0·001), but this sex difference was not seen in dwarf rats. A continuous infusion of human GH in dwarf males raised plasma GHBP to 23·5 ± 3·5 μg/l compared with 6·7 ± 0·5 μg/l in sham-infused animals, whereas suppression of GH by continuous infusion of a long-acting somatostatin analogue in female dwarf rats had no effect on GHBP. In anaesthetized rats, large changes in plasma GH caused by i.v. administration of rat GH, somatostatin or GH-releasing factor did not affect GHBP acutely. Both GH and GHBP were also measured in serial blood samples from conscious normal and dwarf rats. A sexually dimorphic GH secretory pattern was observed in both strains. Males showed peaks and troughs of GH every 3 h varying over a 100-fold range, whereas females exhibited more continuous GH secretion. Despite the large fluctuations in endogenous GH, GHBP levels remained relatively constant in individual normal or dwarf males, as well as in females of both strains, and there was no significant correlation between GH and GHBP either in individual rats or as a group. Our results suggest that GHBP is GH-dependent in the longer term, and that the higher GHBP levels in female rats require their continuous GH secretory pattern. However, plasma GHBP levels remain stable and are not affected by acute changes in endogenous or exogenous GH.
Journal of Endocrinology (1992) 135, 447–457
Immunization with human thyrotrophin receptor peptide induces an increase in thyroid hormone in rabbits
Authors: Ohmori M. , Endo T. , Ikeda M. , Onaya T. 
Published: December 2008

ABSTRACT
Eight rabbits were immunized with a synthetic peptide corresponding to the unique N-terminal region (termed N peptide; amino acid residues 29–57) in the extracellular domain of the human thyrotrophin (TSH) receptor. After 10 weeks, all of the eight rabbits produced anti-N peptide antibodies. Western blot analysis revealed that the antibodies recognized rabbit TSH receptor as an approximately 100 kDa protein. We compared the level of thyroid hormone in serum taken before immunization (preimmune sera) with that of serum taken after immunization (postimmune sera) in these immunized rabbits. Postimmune sera from the eight rabbits had higher mean (± s.d.) levels of tri-iodothyronine (T3) and thyroxine (T4) than did preimmune sera (T3, preimmune 0·82 ± 0·26 μg/l vs postimmune 1·33 ± 0·35, P < 0·01; T4, preimmune 33·7 ± 10·0 μg/l vs postimmune 41·0 ± 6·0, P < 0·05). T3 levels in four rabbits and T4 levels in four rabbits after immunization were over the normal range obtained from six age-matched control rabbits. Seven rabbits exhibited thyroid-stimulating antibody (TSAb) activity with various degrees (241–545%). The concentration of T3 and T4 did not increase over 10 weeks in either non-immunized rabbits (T3, preimmune 0·89 ± 0·34 μg/l vs postimmune 0·82 ± 0·22; T4, preimmune 31·1 ± 7·3 μg/l vs postimmune 30·3 ± 5·1) or other peptide-immunized rabbits (T3, preimmune 0·68 μg/l (n = 2) vs postimmune 0·69; T4, preimmune 33·1 μg/l vs postimmune 26·4). These results indicate that experimentally produced anti-TSH receptor antibody with TSAb activity induces an increase in thyroid hormone in rabbits.
Journal of Endocrinology (1992) 135, 479–484
Effects of FSH on Leydig cell morphology and function in the hypogonadal mouse
Authors: O'Shaughnessy P. J. , Bennett M. K. , Scott I. S. , Charlton H. M. 
Published: December 2008

ABSTRACT
The hypogonadal (hpg) mouse has a congenital deficiency in gonadotrophin-releasing hormone and the gonads consequently lack exposure to endogenous gonadotrophins during development. To determine the effect of FSH on Leydig cell function in these animals adult hpg mice were injected twice daily with FSH (2 μg injections) or LH (40 ng injections, the presumed LH contamination of FSH used). Following FSH treatment there was a clear stimulation of the seminiferous epithelium and in animals injected with FSH plus [3H]thymidine, the incorporation of label was largely confined to the germ cells with no apparent uptake by the Sertoli cells. In FSH-treated testes the Leydig cells contained numerous large lipid droplets, similar to the unstimulated hpg testis. There was no evidence of the interstitial hyperplasia which is observed following injection of high doses of LH (2 pg twice daily).
There was no change in basal androgen content of the testis in vivo following FSH treatment but injection of a maximal dose of human chorionic gonadotrophin (hCG), 1 h before death, markedly increased testicular androgen content only in the FSH-treated group. Testicular androgen production in vitro was significantly increased following FSH treatment both under basal conditions (FSH-treated, 17·4 pmol/testis; control, 1·46 pmol/testis) and during stimulation by hCG (FSH-treated, 940 pmol/testis; control, 81 pmol/testis). Associated with the increased androgen production following FSH treatment there were significant increases in the activities of three steroidogenic enzymes; cholesterol side-chain cleavage (186-fold increase over control), 17α-hydroxylase (103-fold increase) and 17-ketosteroid reductase (177-fold increase). The fourth enzyme involved in androgen synthesis, 3β-hydroxysteroid dehydrogenase, shows relatively high activity in the control hpg testis and was only increased by sixfold following FSH treatment. There was no effect of FSH on 5α-reductase activity.
Results show that FSH causes a marked stimulation of the steroidogenic capacity of the hpg testis. Leydig cells do not contain FSH receptors and it is assumed that FSH acts through paracrine factors released by the Sertoli cells.
Journal of Endocrinology (1992) 135, 517–525
Expansion of plasma volume by intragastric isotonic saline inhibits supraoptic neurones in rats
Authors: Pendlebury S. T. , Dyball R. E. J. , Honda K. 
Published: December 2008

ABSTRACT
To determine whether an increase in plasma volume might directly influence supraoptic neurones, single cell extracellular recordings were made from magnocellular neurones of the supraoptic nucleus in urethane-anaesthetized rats as plasma volume was expanded by intragastric injection of isotonic saline. Continuous ratemeter records taken before, during and after intragastric injections of 10 ml isotonic saline showed that the firing rate of putative vasopressin cells was reduced by 2·21 spikes/s (P < 0·02; n = 9; paired t-test) after 50 min. Putative oxytocin cells, after an initial increase in firing rate which lasted approximately 30 min, showed a decrease of 0·98 spikes/s (P < 0·02; n = 6; paired t-test). A population of 93 control cells of both types had a median firing rate of 4·69 spikes/s, a comparable group of 65 cells recorded 1 h after intragastric injection had a median firing rate of 3·15 spikes/s and another group of 68 cells recorded 1 h after a second injection had a median firing rate of 2·5 spikes/s. These differences were significant (P < 0·04 and P < 0·01; Mann–Whitney U test). The haematocrit of plasma samples taken from five similarly anaesthetized control animals was 49·7%. One hour after one intragastric injection the value was significantly (P < 0·02; paired t-test) reduced to 46·7% and 1 h after a second injection it was further reduced to 42·1% (P < 0·01). Thus a modest increase in plasma volume was associated with a reduced firing rate of both vasopressin and oxytocin cells so that it is probable that an increase in plasma volume inhibits the secretion of both neurohypophysial hormones.
Journal of Endocrinology (1992) 135, 527–533
DIRECT STIMULATION OF BOVINE OVARIAN PROGESTERONE SECRETION BY LOW CONCENTRATIONS OF a-INTERFERON
Authors: Luck M.R. , Shale J.A , Payne J.H. 
Published: December 2008

ABSTRACT
The ruminant conceptus secretes proteins during early pregnancy which maintain the corpus luteum. These trophoblast proteins are related to the αII-interferons and prevent luteolysis indirectly by disrupting the secretion of endometrial prostaglandin. Although trophoblast interferons appear to be largely confined to the uterine lumen, it remains possible that they also act peripherally. This report describes in vitro studies which suggest that interferon may influence hormone secretion by the ovary directly. The study employed i) a well defined serum-free culture model in which bovine granulosa cells secrete the luteal hormones progesterone and oxytocin, and ii) serum-free and serum-supplemented cultures of cells from early CL. Dose-response experiments were performed using bovine recombinant α-interferon (brIFN). Progesterone and oxytocin secretions were measured over 4-5 days of culture and DNA content was also determined.
Low concentrations of brIFN (10−15 mol/l to 10−11 mol/l) stimulated progesterone secretion by granulosa cells by up to three fold, without significantly affecting oxytocin concentrations or culture DNA content. Concentrations of 10−10 mol/l to 10−7 mol/l suppressed progesterone secretion in a log dose-related manner (r=0.97) with evidence of toxicity (lower oxytocin concentrations and significantly reduced DNA compared with controls). Progesterone secretion by luteal cells in serum-free culture was stimulated in the presence of 10−15 mol/l brIFN, whilst high concentrations again caused inhibition. The data show that ovarian cells can respond directly to low concentrations of interferon-like proteins. They also demonstrate an inhibition by high doses which may mask the stimulatory effect in this model. The data suggest that the early corpus luteum may be directly influenced by α-interferon. A stimulation of progesterone, but not of oxytocin, secretion from ovarian cells would be consistent with a role for conceptus proteins in maintaining the corpus luteum of pregnancy.
Oxytocin receptor concentrations, inositol phosphate turnover and prostaglandin release by endometrium from ewes induced to ovulate during the early post-partum period
Authors: Wallace J. M. , Thompson M. G. , Aitken R. P. , Cheyne M. A. 
Published: December 2008

ABSTRACT
Induction of ovulation early post partum in sheep is associated with a high incidence (30–40%) of premature luteolysis. The present study was designed to characterize oxytocin receptor levels, oxytocin-stimulated inositol phosphate (IP) turnover (second messenger) and oxytocin-stimulated prostaglandin F2α (PGF2α) release in the endometrium of post-partum ewes induced to ovulate 21 days after parturition and expected to exhibit a range of corpus luteal functions subsequently.
Ovulation was induced on day 21 post partum using a controlled internal drug release device and pregnant mare serum gonadotrophin, and uterine tissues were collected on days 5, 10 or 15 of the cycle (n = 4/day). A further 12 ewes whose interval from previous parturition exceeded 150 days were similarly treated and acted as controls. Measurement of daily peripheral progesterone concentrations revealed that while all control ewes exhibited normal luteal function, abnormal luteal function was evident in two, two and one post-partum ewes studied on days 5, 10 and 15 of the cycle respectively. Oxytocin receptor binding was detected (by receptor-binding assay and in-vitro autoradiography) in the endometrium and myometrium of post-partum ewes at all three stages of the oestrous cycle but only at day 15 in control ewes. To determine IP turnover, 100 mg caruncular endometrium was incubated in duplicate for 2·5 h with 10 μCi [3H]inositol and treated with 0 or 2 μmol oxytocin/l for 30 min, then [3H]inositol mono-, bis- and trisphosphates were quantified. Oxytocin stimulated total IPs in all day-5 and day-15 post-partum ewes, in three of four day-10 ewes and in all day-15 control ewes. Basal endometrial PGF2α release measured in triplicate (100 mg/well) during a 2 h incubation was higher in post-partum versus control ewes on days 5 and 10 but not on day 15 of the cycle. Similarly, oxytocin stimulated PGF2α release to varying levels at all stages of the cycle in post-partum ewes but only on day 15 in control ewes. Irrespective of the treatment group endometrial oxytocin receptor number was significantly (P < 0·001) correlated with oxytocin-stimulated IP turnover and PGF2α release.
Thus the induction of ovulation and the subsequent luteal phase in post-partum ewes is against a back ground of high oxytocin receptor expression and enhanced PGF2α release which in some ewes may contribute to abnormal luteal function.
Journal of Endocrinology (1993) 136, 17–25