bluuebunny/crossref_metadata_2025_split huggingface dataset:
Treatment with bovine follicular fluid suppresses follicular development in gonadotrophin-releasing hormone-treated anoestrous ewes
Authors: Hunter M. G. , Hindle J. E. , McLeod B. J. , McNeilly A. S. 
Published: December 2008

ABSTRACT
The role of FSH in gonadotrophin-releasing hormone (GnRH)-induced follicular development in anoestrous ewes was investigated using injections of bovine follicular fluid (bFF) to reduce plasma FSH levels. Groups of five animals were treated for 12 h with GnRH (250 ng at 2-h intervals) alone, GnRH plus bFF or saline alone, or for 36 h with GnRH alone, GnRH plus bFF or bFF alone. The administration of bFF (1·5 ml s.c. at 8-h intervals) significantly (P<0·05) reduced mean plasma FSH levels, but with the exception of animals treated with bFF alone, had no effect on LH levels. Treatment with bFF alone for 36 h resulted in a significant (P<0·05) increase in LH concentrations. There was considerable variation in the number of follicles ≥2 mm in diameter in the treatment groups. The mean diameter, oestradiol secretion and number of 'oestrogenic' follicles were significantly (P<0·01) reduced in ewes treated with GnRH plus bFF or bFF alone for 36 h compared with those treated with GnRH alone. Testosterone secretion by the follicles was not affected by treatment.
These results confirm previous findings that treatment with bFF decreases circulating FSH levels in anoestrous ewes and, moreover, that concurrent administration of bFF and GnRH inhibits the follicular maturation that is induced by treatment with GnRH alone, suggesting that FSH as well as LH is required for follicular maturation in the ewe.
J. Endocr. (1988) 119, 95–100
Characteristics of milk ejection, associated intramammary pressure changes and oxytocin release in the mare
Authors: Ellendorff F. , Schams D. 
Published: December 2008

ABSTRACT
The neuroendocrine reflex theory of milk ejection was investigated in the horse under natural suckling conditions. To this end 12 lactating mares were provided with acute jugular catheters and with intramammary pressure (IMP) recording catheters. The foal had free access to the contralateral mammary complex. Intramammary pressure could thus be recorded while blood was drawn simultaneously for oxytocin analysis from the undisturbed animal. Suckling periods associated with a characteristic increase in IMP lasted significantly longer than unsuccessful nursing attempts. Elements of successful sucklings involved physical stimulation of the mammary gland, a quiet phase and a sudden increase in IMP. Successful suckling took place at about 20-min intervals with a wide range from < 5 min to > 100 min. Between 5 and 10 mU oxytocin i.v. were sufficient to evoke an increase in IMP identical in shape and duration to a naturally induced increase in IMP. Mean peak oxytocin levels reached 15·8 pmol/l plasma, with a maximal release of 39 pmol/l. In the majority of cases (> 80%) peak oxytocin release did not occur until after the increase in IMP; in some cases an oxytocin surge was not detectable at all, despite a milk ejection-associated increase in IMP. In three cases increase in IMP could be observed while the foals were away from the mother with no signs of any intention to suckle. The data indicate that in the horse some elements of the neuroendocrine reflex, such as tactile stimulation of the teat and a surge of oxytocin before an increase in IMP, are facultative and not essential for normal milk ejection.
J. Endocr. (1988) 119, 219–227
Facilitated calcium mobilization and inositol phosphate production in the priming effect of LH-releasing hormone in the rat
Authors: Mitchell R. , Johnson M. , Ogier S.-A. , Fink G. 
Published: December 2008

ABSTRACT
The ability of LHRH to induce Ca2+ mobilization and production of inositol phosphates in rat anterior pituitary tissue in vitro was investigated in relation to the self-priming effect of LHRH. Prior exposure to LHRH (which caused a characteristic potentiation of subsequent secretory responses) specifically enhanced LHRH-induced inositol phosphate production and mobilization of intracellular Ca2+ stores. LHRH-induced influx of Ca2+ through dihydropyridinesensitive Ca2+ channels was unaltered, as was ligand binding to LHRH receptors. These data suggest that a novel facilitation of signalling may occur in the phospho-inositide-Ca2+ mobilization response mechanism during LHRH priming, and that this may represent an important means of regulating cellular responsiveness in gonadotrophs.
J. Endocr. (1988) 119, 293–301
Effect of tamoxifen on oestrogen binding, lipid and lipoprotein concentrations and blood clotting parameters in premenopausal women with breast pain
Authors: Caleffi M. , Fentiman I. S. , Clark G. M. , Wang D. Y. , Needham J. , Clark K. , La Ville A. , Lewis B. 
Published: December 2008

ABSTRACT
As part of a controlled trial of the use of tamoxifen for the treatment of mastalgia, some of the metabolic and haematological effects of this agent were measured. A panel of haemostatic variables including prothrombin time, kaolin cephalin clotting time, fibrinogen, euglobulin lysis time, factor VII, factor VIII, protein C and anti-thrombin III were determined. In addition, levels of sex hormone-binding globulin and both total and free oestradiol were estimated. No alteration in clotting function was found during the administration of tamoxifen, although hepatic function did alter during this period with an increase in concentration of sex hormone-binding globulin. There was a significant increase in total oestradiol and free oestradiol although the percentage of biologically available free oestradiol fell slightly during the course of tamoxifen treatment. There was a slight reduction in low-density lipoprotein cholesterol with an increase in HDL2, a subclass of high-density lipoprotein (HDL) cholesterol, consistent with an oestrogen-agonist effect. These data suggest that tamoxifen administration does not adversely influence haemostatic mechanisms or lipoprotein metabolism in the short term.
J. Endocr. (1988) 119, 335–339
Sensitization and desensitization of human thyroid cells in culture: effects of thyrotrophin and thyroid-stimulating immunoglobulin
Authors: Kraiem Z. , Alkobi R. , Sadeh O. 
Published: December 2008

ABSTRACT
Using an in-vitro system of cultured human thyroid cells and cyclic AMP (cAMP) accumulation as an index of cell stimulation, we compared TSH and thyroid-stimulating immunoglobulin (TSI) with regard to thyrocyte sensitization and desensitization. The smallest dose of TSH (0·05 mU/ml) capable of stimulating thyroid cells was the same as the minimum dose required to induce desensitization upon subsequent rechallenge with the hormone. In contrast, about 30-fold higher doses of TSI were needed to cause cell refractoriness compared with doses capable of eliciting stimulation. Moreover, significant stimulation of the thyroid with TSI was apparent much later than with TSH. A longer time-lapse was also necessary for TSI to induce densensitization. Likewise, thyrocytes recovered more slowly from TSI compared with TSH desensitization. Although at high doses TSI induced homologous desensitization, at lower doses the antibody, unlike TSH, potentiated the cAMP response to subsequent exposure to the antibody. The stimulatory doses of TSI were in the range usually encountered in active Graves' disease, which may explain why prolonged TSI in vivo sustains a hyperthyroid condition. In addition, we found that under conditions in which TSH leads to desensitization of the cAMP response, the thyroid cells maintained their responsiveness in terms of triiodothyronine secretory activity. Pre-exposure of human thyrocytes to TSI induced heterologous desensitization towards the TSH-stimulated cAMP response. Moreover, addition of the antibody to maximally desensitizing doses of TSH decreased cell sensitivity to the hormone even further. In sharp contrast, preincubation of cells with TSH, or TSH plus TSI, potentiated by four- and twofold respectively the cAMP response to subsequent challenge with TSI. Taken together, the data reveal marked differences between the action of TSH and TSI, and raise interesting questions concerning the mechanism whereby TSH potentiates the cAMP response to TSI.
J. Endocr. (1988) 119, 341–349
Biopotency of highly purified porcine FSH and human LH on gonadal function
Authors: Closset J. , Hennen G. 
Published: December 2008

ABSTRACT
The gonadotrophin preparations that have been used previously to study different aspects of testis function are of limited purity. We have, therefore, purified existing gonadotrophin preparations further. The demonstration of their purity and biological activity are reported as well as their suitability for in-vivo use.
After separation of the subunits of the intact hormones by high-performance liquid chromatography followed by analytical sodium dodecylsulphatepolyacrylamide gel electrolphoresis, no contaminating proteins could be detected in either the FSH or LH preparation. After immunoadsorption, contamination by other pituitary hormones (TSH, prolactin, FSH, LH and GH) was found to be less than 0·002% by weight for all the hormones tested. The biological activity of porcine FSH (pFSH) measured in a Steelman–Pohley assay was 150–170 times more potent than the NIH-FSH-P1 reference preparation. The biopotency of human LH (hLH) in the ovarian ascorbic acid depletion test was measured and appeared to be 8100–8300 IU/mg against the 68/40 International Standard.
The dose-dependent effects of pFSH and hLH on testis weight and the number of FSH and LH receptors were measured in immature (22-day-old) hypophysectomized rats treated for 7 consecutive days. Treatment with FSH induced a dose-dependent increase in testis weight (threefold) when compared with the control. The concentration and total number of LH receptors were increased (two- to sixfold) in a dose-dependent manner. The number of FSH receptors per testis increased while the number of FSH receptors per mg of protein remained unchanged. Administration of human LH to immature hypophysectomized rats had no effect on either LH or FSH receptors, regardless of the dose administered. The plasma concentration of testosterone measured after seven injections of FSH remained at the level of (0·31 nmol/l) found in saline-injected control rats. After 7 days of treatment with hLH, the plasma concentration of testosterone had increased in a dose-dependent manner (three- to tenfold). These results indicate that the gonadotrophin preparations are both highly purified and retained full biological activity and, therefore, are ideal for in-vivo physiological studies.
Journal of Endocrinology (1989) 120, 89–96
Osmotic regulation of hypothalamo-neurointermediate lobe corticotrophin-releasing factor-41 in the rat
Authors: Jessop D. S. , Eckland D. J. A. , Todd K. , Lightman S. L. 
Published: December 2008

ABSTRACT
We have detected significant amounts of corticotrophin-releasing factor-41 (CRF-41) in the rat hypothalamo-neurointermediate lobe system using a radioimmunoassay and reversed-phase high-performance liquid chromatography. Total amounts of CRF-41 in extracts of median eminence (ME), supraoptic nucleus (SON), paraventricular nucleus (PVN) and neurointermediate lobe (NIL) from control animals were 1076 ± 132, 196 ± 44, 22 ± 7 and 147 ± 50 fmol respectively (means ± s.e.m., n = 6). In animals given 340 mmol NaCl/l instead of tap water to drink for 12 days, no significant changes occurred in the CRF-41 content of the ME, SON or PVN, but CRF-41 content increased more than twofold in the NIL (362 ± 58 fmol). Plasma concentrations of CRF-41 and ACTH in control animals were 23 ± 6 and 51 ± 8 pmol/l respectively. After saline treatment no significant change in plasma CRF-41 was detected (20 ± 8 pmol/l) but concentrations of circulating ACTH were decreased (15 ± 2 pmol/l). The CRF-41 content of both the ME and the NIL was significantly depleted after intracerebroventricular injection of colchicine (414 ± 81 and 34 ± 7 fmol respectively). These data suggest that NIL CRF-41 is of hypothalamic origin and can be regulated by an osmotic stimulus.
Journal of Endocrinology (1989) 120, 119–124
Effects of porcine growth hormone and insulin-like growth factor-I (IGF-I) on immunoreactive IGF-binding protein concentration in pigs
Authors: Walton P. E. , Etherton T. D. 
Published: December 2008

ABSTRACT
A specific radioimmunoasay (RIA) was established for an acid-stable insulin-like growth factor-binding protein (IGF-BP) isolated from porcine serum. The RIA recognizes a GH-dependent 150 kDa protein in porcine serum; therefore we postulate that the acid-stable IGF-BP is a component of the high molecular weight IGF-BP in porcine serum.
The IGF-BP concentration was assayed in porcine serum (normal, 2·44 mg/l; hypophysectomized, 0·83 mg/l; serum from a GH-treated pig, 4·72 mg/l), porcine colostrum (2·55 mg/l), milk (0·91 mg/l), and amniotic (1·82–3·14 mg/l), allantoic (2·94–3·58 mg/l) and follicular (2·28 mg/l) fluids.
Serum concentrations of IGF-BP were significantly increased (63%) in pigs chronically injected with porcine GH (pGH) (70 μg/kg body weight per day for 17 days). Concentrations of IGF-BP did not change in porcine serum following acute challenges with pGH (10–1000 μg/kg body weight) or IGF-I (4 or 8 mg per pig).
This is the first report of a specific RIA for the porcine GH-dependent IGF-BP. Our results indicate that this IGF-BP is found in a wide variety of biological fluids and that its concentration appears to be regulated by pGH but not by IGF-I.
Journal of Endocrinology (1989) 120, 153–160
Effects of the new prolactin-producing tumour 7315b on gonadotrophin secretion in adult male and female rats
Authors: Kooy A. , Weber R. F. A. , Ooms M. P. , Vreeburg J. T. M. 
Published: December 2008

ABSTRACT
The effects of the transplantable purely prolactin-secreting tumour 7315b on serum gonadotrophins were studied in adult rats. Possible contributions of the adrenals to the tumour-induced inhibition of serum LH and FSH were evaluated. The suppressive actions of tumour 7315b on serum gonadotrophins in gonadectomized plus adrenalectomized male and female rats were compared.
Within 4 weeks after inoculation of tumour 7315b in intact male rats very high levels of prolactin and decreased serum levels of gonadotrophins and testosterone were recorded. At autopsy reduced weights of testes and accessory sex organs and slightly increased adrenal weights were found. In addition, in animals treated with a small testosterone-filled capsule after castration, tumour 7315b reduced serum concentrations of LH and FSH. Adrenalectomy did not prevent this suppressive action of the tumour on the post-castration rise of serum gonadotrophins. Suppression of serum gonadotrophins during hyperprolactinaemia was greater in gonadectomized plus adrenalectomized female rats than in male rats, indicating that the degree of the tumour-induced suppression of LH and FSH after castration is determined to a large extent by the sex of the animal.
The purely prolactin-secreting tumour 7315b has therefore been shown to be a suitable model for studying the effects of severe hyperprolactinaemia on the pituitary-gonadal axis in rats.
Journal of Endocrinology (1989) 120, 261–268
Adenosine 3',5-cyclic monophosphate phosphodiesterase activity in granulosa cells from Booroola × Romney ewes with and without the F gene
Authors: McNatty K. P. , Heath D. A. , Lun S. , Hudson N. L. 
Published: December 2008

ABSTRACT
Granulosa cells from ovarian follicles (≥ 1 mm diameter) in Booroola ewes which are homozygous (FF) or heterozygous (F+) for the F gene have previously been shown to produce significantly more cAMP in response to FSH or LH than those from similar sized follicles in ewes without the F gene (++). The aim of these studies was to test whether these F gene-specific differences arose because of differences in cAMP-phosphodiesterase (cAMP-PDE) activity.
In the first study using 1 μmol cAMP/1 as substrate, no F gene-specific effects were noted in cAMP-PDE activity in granulosa cells from small (1–2·5 mm diameter, n = 4 per genotype) or large (≥ 3 mm diameter, n = 4 per genotype) follicles from FF, F+ or ++ ewes, despite F gene-specific effects in FSH (1 μg/ml)and LH (0·1 μg/ml)-induced cAMP accumulation in these same cell preparations. The overall mean levels of cAMP-PDE across all genotypes in cells from small and large follicles were 0·47± 0·04 (s.e.m., n = 12) and 0·28 ± 0·03 pmol cAMP/106 cells per min respectively; the mean PDE activity in cells from small follicles was significantly (P < 0·05) higher compared with that in cells from large follicles. In a second study, granulosa cells from each genotype were pooled over all follicle sizes (≥ 1 mm diameter, one pool per genotype) and the rates of cAMP hydrolysis tested over a range of substrate concentrations (0–16 μmol/l) but no genespecific differences with respect to the Michaelis constant and maximum velocity were noted. In a third study, the rates of FSH-induced cAMP accumulation by granulosa cells from small and large follicles of FF and ++ ewes were examined in the presence of a PDE inhibitor, 1-methyl-3-isobutylxanthine (0·2 mmol/l). In this study FSH (1 μg/ml) stimulated significantly more cAMP in cells from FF compared with ++ ewes in both small and large follicles. In cells from small follicles, the mean ± s.e.m. FSHstimulated cAMP levels were 4·7 ± 0·8 (n = 6) for FF ewes and 1·8 ± 0·4 (n = 8) pmol/106 cells per h for ++ ewes (P < 0·025). In large follicles, the cAMP levels were 17·0 ± 3·5 (n = 6) for FF ewes and 6·3 ± 0·5 pmol/106 cells per h for ++ ewes (P < 0·05).
Collectively, these data suggest that the F genespecific difference in cAMP synthesis is probably the result of an event(s) associated with its formation rather than its degradation.
Journal of Endocrinology (1989) 120, 287–293
Age-related variation in circadian rhythms of mitosis in the adrenal cortex of the male rat
Authors: McNicol A. M. , Penman I. D. , Duffy A. E. 
Published: December 2008

ABSTRACT
Using a metaphase arrest technique, mitotic activity was quantified in the adrenal cortex over a 24-h period in 14-day-old male Sprague–Dawley rats before functional rhythmicity of the hypothalamic pituitary-adrenal (HPA) axis is established, and after its onset, in 6- to 7-week-old rats. At all times, proliferative activity was greater in the younger animals, as previously reported. A significant circadian rhythm was identified in both groups, but the timing of the peak differed, lying between 17.00 and 21.00 h at 14 days and 11.00 and 15.00 h at 6–7 weeks. These results raise the possibility that functional rhythmicity of the HPA axis may alter an inherent proliferative rhythm.
Journal of Endocrinology (1989) 120, 307–310
Effects of insulin, glucose and ACTH on corticosterone production by fetal adrenal cells from diabetic rats
Authors: Conliffe P. , Mulay S. 
Published: December 2008

ABSTRACT
Experiments were carried out on Sprague–Dawley rats to determine whether changes in fetal corticosterone levels during maternal diabetes were caused by the accompanying fetal hyperinsulinaemia or fetal hyperglycaemia. Diabetes was induced by injecting streptozotocin (30–45 mg/kg, i.v.) on day 2 of gestation. Fetal adrenals were removed on day 20 of gestation and cultured. Streptozotocin caused moderate (blood glucose 14–22·5 mmol/l) to severe (blood glucose >25 mmol/l) diabetes. Both moderate and severe diabetes caused a decrease in fetal body weights. Relative to non-diabetic controls, maternal and fetal plasma concentrations of corticosterone were higher in the severely and lower in the moderately diabetic rats. Corticosterone production by fetal adrenal cells from control and moderately diabetic rats was comparable, but cells from the severely diabetic animals produced significantly greater amounts of corticosterone than did control cells. Neither glucose (28 mmol/l) nor insulin (1 nmol/l) exerted significant effects on [3H]thymidine uptake or corticosterone production by fetal adrenal cells from non-diabetic, moderately diabetic or severely diabetic rats. Human ACTH (0·02–20 nmol/l) caused a concentration-dependent increase in corticosterone output of comparable magnitude by cells from all three groups of animals. These data suggest that fetal growth abnormalities during diabetic pregnancy are not directly related to changes in glucocorticoid levels and that changes in glucocorticoid levels are not caused by any direct action of fetal hyperinsulinaemia or hyperglycaemia on adrenal cells.
Journal of Endocrinology (1989) 120, 393–399
High-density lipoproteins (HDL) stimulate placental lactogen secretion in pregnant ewes: further evidence for a role of HDL in placental lactogen secretion during pregnancy
Authors: Grandis A. , Jorgensen V. , Kodack L. , Quarfordt S. , Handwerger S. 
Published: December 2008

ABSTRACT
Previous studies from our laboratory showed that high-density lipoproteins (HDL) stimulate the release of human placental lactogen (PL) from cultured trophoblast cells from normal pregnant women. To determine whether HDL stimulates PL secretion in vivo, ovine HDL was infused over 2–5 min into 11 pregnant ewes (22 separate experiments) at 86–130 days of gestation via an indwelling catheter into the maternal jugular vein. The HDL, freshly prepared from the plasma of pregnant ewes by differential flotation ultracentrifugation, was greater than 99% purified as judged by SDS-PAGE. Plasma samples were obtained from the ewes before and at 0·5-h intervals for 6 h following the infusions and were assayed for PL by a specific homologous radioimmunoassay. The maternal infusion of HDL at doses of 302–784 mg (5·3–13·8 mg/kg body weight) stimulated significant increases in maternal plasma PL concentrations in six out of eight experiments (six ewes), and the infusion of 108–264 mg (1·9–4·6 mg/kg) stimulated plasma PL concentrations in two out of six experiments. In contrast, HDL at doses < 100 mg were without effect in eight experiments. The response to the HDL infusions was characterized by a sustained increase in plasma PL concentrations beginning 1·5–2·5 h after the infusions, reaching a maximum 274·2 ± 21·9% of the baseline value (P<0·001). In contrast, the maternal infusion of lipoprotein-free plasma proteins or saline had no effect on maternal plasma PL concentrations. Although the infusion of HDL into pregnant ewes stimulated an increase in maternal plasma PL concentrations, the infusion of HDL (0·8–22·0 mg/kg) into three fetuses in seven separate experiments had no effect on fetal plasma PL concentrations. The demonstration that HDL stimulates an increase in plasma PL concentrations in pregnant ewes strongly supports a novel physiological role for HDL in the regulation of PL secretion.
Journal of Endocrinology (1989) 120, 423–427