bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of the daily administration of gonadotrophin-releasing hormone on the anterior pituitary gland of rats with restricted feeding
Authors: Kotsuji F. , Hosokawa K. , Tominaga T. 
Published: December 2008

ABSTRACT
To investigate the influence of weight reduction on pituitary function and its modulation by gonadotrophin-releasing hormone (GnRH), female rats were restricted to 10 g food/day for 60 days. GnRH (5 μg) or saline (0·2 ml) were administered daily between days 31 and 60 of the period of underfeeding. Underfeeding brought about a decrease in the pituitary gonadotrophin content, serum levels of gonadotrophins and oestradiol, and the number and size of both LH- and FSH-positive pituitary cells. The administration of GnRH to underfed rats produced an increase in the pituitary and serum gonadotrophin levels and the number and size of both LH- and FSH-positive pituitary cells. These observations suggest that underfeeding and/or weight loss diminish the number and activity of the pituitary gonadotrophs, and that daily administration of GnRH both increases the number of gonadotrophs and augments their activity.
Journal of Endocrinology (1992) 134, 177–182
Lung to blood passage of human growth hormone after intratracheal instillation: stimulation of growth in hypophysectomized rats
Authors: Folkesson H. G. , Hedin L. , Weström B. R. 
Published: December 2008

ABSTRACT
The passage from the lower respiratory tract into the blood of human GH (hGH; Mr = 22 000) and bovine serum albumin (BSA; Mr = 67 000) was assessed after intratracheal instillation in adult rats. The plasma level of immunoreactive hGH reached its maximum at 0·5–1 h after instillation and had almost disappeared within 24 h. Higher plasma levels were obtained in male rats than in female rats resulting in a higher total lung passage of hGH in male rats than in female rats (means±s.d.; 6·0± 1·7% vs 3·3±1·2%, P <0·01). The plasma level of BSA showed a different pattern, with a maximum at 16–24 h after instillation and a total lung passage of 4·3 ± 1·7% of the given dose for both sexes. The plasma levels of hGH increased non-linearly with increasing dose instilled in the dose range 36–720 μg/kg body weight. When hGH was instilled daily at a dose of 720 μg/kg body weight to hypophysectomized rats for 1 week, they responded with a significant increase in body weight when compared with hypophysectomized control rats (16·8±4·2 g vs −1·8±2·4 g, P <0·001).
The results demonstrate that, despite their different molecular weights, hGH and BSA pass through the lower respiratory tract into the circulation with similar efficiencies in the rat. However, the lung passage of hGH, unlike that of BSA, showed sexual dependency, an earlier plasma concentration maximum and a tendency of the passage to saturation with increasing dose instilled. Since hGH was shown to be biologically active after the passage through the lungs, the lung may be a potential new route for hGH administration.
Journal of Endocrinology (1992) 134, 197–203
Pituitary-testis function in rats treated neonatally with a gonadotrophin-releasing hormone agonist: short- and long-term effects
Authors: Garnelo P. , Pinilla L. , Gaytan F. , Aguilar E. 
Published: December 2008

ABSTRACT
Acute and long-term effects of neonatal and prepubertal treatments with an LH-releasing hormone agonist (LHRH-A) were studied in Wistar male rats. Animals injected with d-Ala6-d-Gly10-LHRH ethylamide (2 μg/kg per day) or vehicle from days 1 to 15 or from days 16 to 29 were killed at different ages. Treatment between days 1 and 15 induced a decrease in both pituitary FSH and LH content as well as a reduction in plasma FSH and blockade of the response to LHRH. These effects were apparent on day 16 after treatment. Basal and human chorionic gonadotrophin (hCG)-stimulated progesterone and testosterone secretion in vitro was similar in testes from male rats treated with LHRH-A or vehicle. Reduced testicular weight was observed until day 90, whereas puberty, spermatogenesis and fertility were unaffected. The decrease in plasma FSH concentrations after neonatal treatment with LHRH-A was also found in groups of animals killed on day 10 and was possibly the cause of reduced testicular weight, since treatment with FSH from day 1 to day 15 blocked the effect of LHRH-A. Likewise, treatment with LHRH-A from day 1 to day 15 also reduced FSH and LH secretion in males orchidectomized on day 1 of life.
Animals injected with LHRH-A from day 15 to day 29 exhibited, at the end of the treatment period, reduced testicular weight, and decreased pituitary gonadotrophin content and plasma FSH concentrations, whereas LH plasma concentrations were normal. In adulthood, the pituitary-testis function did not vary from normal. Our results demonstrate that: (1) administration of LHRH-A from day 1 to day 15 of life desensitized the gonadotrophs, which in turn lowered plasma gonadotrophin concentrations and caused a long-term reduction in testis weight without changes in the quality of spermatogenesis or reproductive activity in adulthood; (2) chronic treatment with LHRH-A during the neonatal period did not result in a steroidogenic lesion; and (3) administration of LHRH-A from day 15 to day 29 produced only a transient reduction in testicular weight and in spermatogenesis.
Journal of Endocrinology (1992) 134, 269–277
Bioactive and immunoreactive FSH and immunoreactive inhibin concentrations in the ovine fetus
Authors: Phillips D. J. , Smith P. R. , Heath D. A. , Condell L. A. , McNatty K. P. 
Published: December 2008

ABSTRACT
The bioactive (B) and immunoreactive (I) pituitary contents/concentrations of FSH, together with the plasma concentrations of B-FSH, I-FSH and I-inhibin were determined in ovine fetuses at days 55, 75, 90 and 135 of gestation (day 145 = term). The pituitary contents and concentrations of B-FSH and I-FSH increased in both sexes with gestational age. The female fetuses had significantly (P <0·01) higher pituitary contents/concentrations of B-FSH and I-FSH than the male fetuses at days 75 and 135. The pituitary B/I ratios of FSH were not significantly different with age or sex. The plasma concentrations of B-FSH remained relatively constant from days 75 to 135, with no significant differences between sexes or with age. In contrast, the plasma concentrations of I-FSH reached a peak at day 90 and then declined towards term in both sexes. At all gestational ages except day 55, the female fetuses had significantly (P <0·05) higher plasma concentrations of I-FSH than the males. In both sexes, the plasma B/I ratios of FSH were lowest at day 90 and had increased again by day 135, with the male fetuses having significantly (P <0·05) higher B/I ratios compared with the female group at days 75 and 135 but not at day 90. At all gestational ages, the plasma concentrations of I-inhibin declined throughout gestation in the female fetuses, whereas in the males they reached a nadir at day 75 and then increased towards term. The concentrations of I-inhibin were significantly (P <0·01) higher in the male fetuses compared with the females. Collectively, these data suggest that there are changes in the forms of FSH present in the pituitary gland and plasma throughout gestation in the ovine fetus. Moreover, they infer that the difference between the sexes in FSH synthesis and/or secretion may be attributed in part to the circulating concentrations of inhibin.
Journal of Endocrinology (1992) 134, 287–295
Inhibitory action of somatostatin-14 on hormone-stimulated cyclic adenosine monophosphate induction in porcine granulosa and luteal cells
Authors: Rajkumar K. , Kerr D. E. , Kirkwood R. N. , Laarveld B. 
Published: December 2008

ABSTRACT
Somatostatin-14 (SRIF-14) inhibited, in a concentration-dependent manner, LH- and forskolin-stimulated cyclic adenosine monophosphate (cAMP) induction in porcine granulosa and luteal cells. The inhibitory effect of SRIF-14 on hormone-induced cAMP generation was more potent in porcine ovarian cells than in the GH-3 pituitary cell line. The inhibitory effect of SRIF-14 was impeded by neutralizing its biological activity with specific antiserum. Preincubation of luteal and granulosa cells with phorbol 12-myristate 13-acetate (PMA) enhanced LH- and forskolin-stimulated cAMP levels. SRIF-14 failed to inhibit LH- or forskolin-stimulated cAMP levels in cells preincubated with PMA. It is concluded that SRIF-14 inhibits hormone-stimulated cAMP induction in the porcine ovary. LH-induced protein kinase C activation may be physiologically important to alleviate the inhibitory effects of SRIF-14.
Journal of Endocrinology (1992) 134, 297–306
Distribution of relaxin between human maternal and fetal circulations and amniotic fluid
Authors: Johnson M. R. , Abbas A. , Nicolaides K. H. , Lightman S. L. 
Published: December 2008

ABSTRACT
Relaxin was measured in maternal blood and amniotic fluid samples at 9–40 weeks and in fetal blood samples at 19–41 weeks of pregnancy. In amniotic fluid, concentrations of relaxin rose from 58 ng/1 (geometric mean) at 10 weeks to 142 ng/l at 14 weeks and declined subsequently to 55 ng/l at 22 weeks. In maternal blood, mean relaxin concentrations were ten times greater than in amniotic fluid, and concentrations decreased with gestation. Since there was no significant association between the relaxin concentrations in the two compartments, relaxin in the amniotic fluid may be derived from the decidualized endometrium rather than the maternal circulation, alternatively its metabolism may be different in the two compartments. The absence of detectable concentrations of relaxin in any of the fetal blood samples demonstrates that there is no significant placental transfer or fetal synthesis of this peptide.
Journal of Endocrinology (1992) 134, 313–317
The effect of gonadotrophin surge-inhibiting factor on the self-priming action of gonadotrophin-releasing hormone in female rats in vitro
Authors: Koppenaal D. W. , Tijssen A. M. I. , de Koning J. 
Published: December 2008

ABSTRACT
The present study was designed to explore further the functional antagonism between gonadotrophin-releasing hormone (GnRH) and the ovarian factor, gonadotrophin surge-inhibiting factor (GnSIF). In all experiments, pituitary tissue was exposed to various amounts of GnSIF, after which the self-priming action of GnRH was studied. GnSIF was increased in vivo by FSH treatment and increased in vitro by adding various amounts of follicular fluid (FF) to cultured pituitary cells.
Treatment with 3 or 10 IU FSH suppressed the initial LH response and delayed the maximally primed LH response to GnRH. Treatment with FSH was only effective in intact rats on days 1 and 2 of dioestrus. There was no difference in the rate of maximal LH release irrespective of treatment with either FSH or saline. Since FSH treatment was ineffective in long-term ovariectomized rats, it was concluded that the initial suppressive effect of FSH on LH release was mediated by GnSIF.
Cycloheximide prevented the self-priming action of GnRH by inhibiting GnRH-induced protein synthesis. The initial protein synthesis-independent GnRH-stimulated LH release, which was already suppressed by FSH treatment, remained suppressed in the presence of cycloheximide. Pretreatment with GnRH in vivo increased the protein synthesis-independent GnRH-induced LH release during subsequent incubation of the glands. This increase did not occur after FSH treatment.
Pituitary cells, cultured for 20 h in medium only, failed to elicit the self-priming effect of GnRH. Preincubation with FF maintained the self-priming effect. This was independent of the concomitant presence of various amounts of oestradiol. Preincubation with bovine FF suppressed the initial GnRH-stimulated LH release dose-dependently. Porcine FF, human FF and testicular extract suppressed the release of LH in a similar way.
It was concluded that GnSIF suppresses the initial LH response to continuous GnRH stimulation. Increased levels of GnSIF caused by FSH treatment also delayed the primed LH release. The mechanism of functional antagonism between GnSIF and GnRH could give rise to the occurrence of the phenomenon of GnRH self-priming.
Journal of Endocrinology (1992) 134, 427–436
The effects of systemic insulin, insulin-like growth factor-I and growth hormone on bone growth and turnover in spontaneously diabetic BB rats
Authors: Verhaeghe J. , Suiker A. M. H. , Visser W. J. , Van Herck E. , Van Bree R. , Bouillon R. 
Published: December 2008

ABSTRACT
Spontaneously diabetic BB rats have a markedly depressed longitudinal bone growth and bone formation/turnover. In this study, male diabetic BB rats were infused intraperitoneally or subcutaneously for 2 weeks with hormones that are believed to stimulate skeletal growth and/or trabecular bone formation: insulin (3 or 4 U/day), human GH (hGH; 400 mU/day), recombinant human insulin-like growth factor-I (rhIGF-I; 300 or 600 μg/day) and testosterone (80 μg/100 g body weight per day).
Saline-treated diabetic BB rats had decreased plasma concentrations of IGF-I and osteocalcin (OC) (OC, 3·7 ±0·3 vs 13·1 ± 0·8 (s.e.m.) nmol/l in controls); bone histomorphometry showed decreased epiphyseal width, osteoblast surface (0·04±0·04 vs 1·5±0·3%) and osteoid surface, and mineral apposition rate (MAR) (1·8±0·5 vs 7·9±0·6 μm/day).
Testosterone and hGH infusions had no effect on weight loss or on decreased skeletal growth and bone formation of diabetic rats, nor did they increase plasma IGF-I concentrations. Insulin infusions into diabetic rats resulted in hyperinsulinaemia and accelerated weight gain. The epiphyseal width, osteoblast/osteoid surfaces and OC levels of insulin-treated rats were normalized or stimulated well above control values (osteoblast surface, 4·3 ±0·8%; plasma OC, 16·1 ± 1·4 nmol/l); the MAR (4·0 ± 0·9 μm/day) was only partly corrected after the 2-week infusion. Infusions of rhIGF-I into diabetic rats doubled but did not restore plasma IGF-I levels to normal; weight gain, however, was similar to that in control rats. IGF-I treatment had no effect on epiphyseal width, osteoblast/osteoid surfaces and OC concentrations, but improved the decreased MAR (4·6±1·2 μm/day).
These results indicate (1) that the decreased epiphyseal width and osteoblast recruitment of diabetic BB rats are directly related to their insulin deficiency, and (2) that IGF-I, administered systemically, corrects, in part, the decreased MAR in diabetes, suggesting a role in osteoblast function and/or mineralization.
Journal of Endocrinology (1992) 134, 485–492
11β-Hydroxysteroid dehydrogenase in the rat ovary: high expression in the oocyte
Authors: Benediktsson R. , Yau J. L. W. , Low S. , Brett L. P. , Cooke B. E. , Edwards C. R. W. , Seckl J. R. 
Published: December 2008

ABSTRACT
The enzyme 11β-hydroxysteroid dehydrogenase (11β-HSD) catalyses the conversion of physiological glucocorticoids to inactive products, thus modifying the access of glucocorticoids to glucocorticoid and mineralocorticoid receptors. Glucocorticoids may affect ovarian function both indirectly and via binding to ovarian receptors. We have demonstrated 11β-HSD bioactivity and mRNA expression in rat ovary in vitro. The enzyme was localized to oocytes and luteal bodies immunohistochemically using two antibodies raised against purified rat liver 11β-HSD. These data are supported by in-situ hybridization studies, which also localized 11β-HSD mRNA expression to oocytes and luteal bodies. The results suggest that 11β-HSD may modulate the effects of glucocorticoid on ovarian function.
Journal of Endocrinology (1992) 135, 53–58
Fluid balance, electrolyte profiles and plasma parathyroid hormone concentrations in ewes treated with epidermal growth factor
Authors: Gow C. B. , Wilkinson M. , Silvapulle M. J. , Moore G. P. M. 
Published: December 2008

ABSTRACT
The infusion of low doses of epidermal growth factor (EGF) into lactating ewes stimulates water intake and urine volume. The plasma concentrations and daily output of various electrolytes in milk and urine are also affected. We have investigated this further by recording the effects of EGF infusion on fluid balance, electrolyte profiles and plasma concentrations of glucose and parathyroid hormone (PTH) in non-pregnant, non-lactating ewes. Twenty-four animals (n= 8 per group) received infusions of 100 ml saline/day into the jugular vein for 10 days (days 1–10) followed by EGF at a dose rate of either 1 (low dose), 5 (medium dose) or 10 (high dose) μg/kg liveweight per day in 100 ml saline for 5 days (days 11–15). All ewes then received an infusion of 100 ml saline/day for 10 days (days 16–25).
Most plasma and urine samples had undetectable concentrations of EGF-immunoreactive material during the periods of saline infusion. During EGF infusion, the highest amounts of EGF infusate excreted in urine were 1·6, 5·9 and 5·6% for ewes in low, medium and high dose groups respectively. Water intake increased by 17% (0·5 kg), 88% (2·5 kg) and 89% (2·3 kg) and urine volume increased by 29% (0·5 kg), 108% (2·2 kg) and 134% (2·1 kg) for the three groups respectively. Fluid balance and feed intake were not affected by EGF infusion, but the output of faecal dry matter was reduced in ewes receiving the two higher doses of EGF.
All levels of EGF resulted in hypocalcaemia, increased plasma PTH concentrations and hypermagnesaemia. There was no effect of EGF on plasma concentrations of K+ and glucose or on daily urinary excretion of K+ and Mg2+. The only response to the low dose was a reduced plasma concentration of Na+ and an increased daily urinary urate excretion. The two higher doses increased the daily urinary excretion of Na+, PO43− and urate, but had no effect on the respective concentrations in plasma. Urinary Ca2+ excretion was reduced only during infusion of the medium dose of EGF.
The responses of most variables were similar during infusion of the medium and high doses of EGF. All three doses of EGF induced polydipsic and diuretic responses in ewes, and infusions of 5–10 μg EGF/kg liveweight per day affected renal excretion of Ca2+, Na+ and PO3−4. We interpret the responses of the kidney and plasma PTH concentrations as a means of maintaining the homeostasis of plasma profiles of electrolytes.
Journal of Endocrinology (1992) 135, 91–101
Comparison of specific immunoassays for detection of the β-core human chorionic gonadotrophin fragment in body fluids
Authors: de Medeiros S. F. , Amato F. , Matthews C. D. , Norman R. J. 
Published: December 2008

ABSTRACT
We have validated two new methods, one radioimmunoassay (RIA) and one immunoradiometric assay (IRMA), for the detection of β-core hCG fragment (βC-hCG) in body fluids. In addition, we have compared their performance with two other assays designed for βC-hCG quantification. The RIA uses a rabbit polyclonal antibody raised against pure βC-hCG which has a high affinity constant, is sensitive to 5 pmol/l, and has significant cross-reaction only with the free βLH subunit. The IRMA, designed in a liquid phase, uses the same polyclonal antibody associated with a 125I-labelled mouse monoclonal antibody (32H2) raised against βhCG, is sensitive to 1·5 pmol/l, and does not cross-react significantly with any related glycoprotein. Comparison between these two assays and two others previously published was made by measuring βC-hCG in urine from healthy pregnant women (n = 47) and gave correlation coefficients higher than r= 0·960 with any combination. Analysis of βC-hCG in urine of non-pregnant subjects (n= 238) showed measurable βC-hCG in 8·8% (levels ranged from 5 to 34 pmol/l) with the IRMA and 88·3% with the RIA (n=30; ranging from 28·4 to 228 pmol/l) (P = 0·05). We concluded that, despite different affinities of the antibody involved and different cross-reactivities with related glycoproteins, the four assays we examined may be equally employed to detect βC-hCG in pregnancy urine. However, the IRMA appears to be more appropriate for βC-hCG analysis in non-pregnant individuals, specifically in postmenopausal women because of the high cross-reactivity of the RIA with free βLH or β fragments of other glycoproteins. These studies have significance for our understanding of the physiology of βC-hCG in cancer, pregnancy and after the menopause,
Journal of Endocrinology (1992) 135, 161–174
Ectopic transcription of the parathyroid hormone gene in lymphocytes, lymphoblastoid cells and tumour tissue
Authors: Handt O. , Reis A. , Schmidtke J. 
Published: December 2008

ABSTRACT
Using reverse transcription polymerase chain reaction, steady-state levels of parathyroid hormone (PTH) mRNA were investigated in a number of human, bovine and rat tissues. Transcripts were consistently detected in parathyroid glands as well as in lymphocytes, lymphoblastoid cells and several tumours. Levels of transcription were not measurably increased in lymphoblastoid cells and tumour tissues compared with unstimulated peripheral lymphocytes. The level of 'ectopic' transcription of the PTH gene in lymphoblastoid cells appeared to be resistant to the administration of both vitamin D and phorbol esters.
Journal of Endocrinology (1992) 135, 249–256
Milking frequency alters the milk yield and mammary blood flow response to intra-mammary infusion of insulin-like growth factor-I in the goat
Authors: Prosser C. G. , Davis S. R. 
Published: December 2008

ABSTRACT
The milk yield and mammary blood flow responses to close-arterial, intra-mammary infusion of IGF-I were investigated in five Saanen goats milked frequently or normally the day before. Animals were infused for 6 h with recombinant human IGF-I (1·3 nmol/min) and milked hourly following i.v. injection of oxytocin beginning 2 h before infusion and then every 2 h. On one occasion animals were milked five times (after i.v. injection of oxytocin) on the day before infusion and on the other they were milked twice, without oxytocin. The ratio of milk yield from the infused to that from non-infused gland increased by 17 ±4% (mean ± s.e.m.) in goats milked twice the day before infusion and by 6 ± 2% when the infusion was preceded by frequent milking. Maximal responses were obtained 4 h after the start of the infusion and differed significantly (P<0·05), according to pretreatment milking. Blood flow through the infused gland rose in parallel to the milk yield response. At 5 h, when maximal levels were achieved, blood flow was 182 ±23% of the pre-infusion flow rate following twice-daily milking and 139 ± 3% of the pre-infusion flow rate following more frequent milk removal. Thus, more frequent milk removal on the day before close-arterial infusion of IGF-I attenuated both the milk yield and mammary blood-flow response to the infusion of IGF-I.
Journal of Endocrinology (1992) 135, 311–316