Acta endocrinologica
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Acta endocrinologica · Jan 1976
Studies on the pattern of circulating steroids in the normal menstrual cycle. I. Simultaneous assays of progesterone, pregnenolone, dehydroepiandrosterone, testosterone, dihydrotestosterone, androstenedione, oestradiol and oestrone.
In an attempt to analyze the multiple changes and interactions in circulating steroid levels in the peri-ovulatory and peri-menstrual periods, the plasma levels of immunoreactive luteinizing hormone (LH), progesterone and unconjugated pregnenolone, dehydroepiandrosterone, testosterone, oestradiol and oestrone were assayed daily during a complete cycle in 17 normally menstruating women. In 14 of the 17 subjects studied androstenedione and unconjugated dihydrotestosterone were also estimated. The day of the LH-peak and the first day of menstruation, respectively, were used to synchronize the peri-ovulatory and peri-menstrual plasma levels of the various steroids. ⋯ The combination of several steroidal signals did not improve the predictive value of the analyses. However, an increase of individual progesterone values by at least 0.35 ng/ml from the day preceding the LH-peak to the day of the LH-peak was observed in 13 of the 17 subjects. It is suggested that for the early detection of the LH surge and prediction of the subsequent ovulation daily assays of plasma progesterone are of more value than the assay of the other steroids investigated.
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The effect of various ergot alkaloids on prolactin (Pr) secretion in adult female rats was determined by radioimmunoassay. Ergocorine (ECO) and ergocristine (ECR) in doses of 0.25 to 1.0 mg lowered serum Pr markedly by 1 h with the effect persisting for 24 h at the larger doses. Several other ergots had similar effects while the dihydro derivatives had diverse responses. ⋯ ECO 1 or 2 mg produced a regression of dimethyl-benz(a)anthracene (DMBA) induced rat mammary tumours which could not be reversed by OeB 5 mug, with persisting low serum Pr. PE 1 mg was able to raise serum Pr and stimulated tumour growth. Several of the ergot alkaloids have a profound inhibiting effect on Pr secretion and may be used for studies on Pr action, as well as in medical therapeutics.
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Acta endocrinologica · Aug 1975
The sequence of pituitary responses to synthetic luteinizing hormone releasing hormone (LH-RH) throughout the normal menstrual cycle.
Thirty-one ovulatory women between 20 and 33 years of age were given 150 mug of synthetic LH-RH during different phases of the menstrual cycle. Five patients were studied during the early follicular phase (days 4-7); 10 patients during the late follicular phase (days 9-12); 6 patients during the "LH Surge"; 5 patients during the early luteal phase (days 14-16); 3 patients during mid-luteal phase (days 17-21); and 2 patients during late luteal phase (days 22-27). Oestrogen, progesterone, FSH and LH levels were determined from 30 min prior to LH-RH administration to 90 min thereafter in all cases. ⋯ Maximum pituitary responsiveness appears to occur in a gonadal steroid milieu of high oestrogen levels in association with rising but low progesterone levels. Progesterone or a crucial oestrogen: progesterone ratio may in fact potentiate pituitary release of LH during the early stages of corpus luteum formation. Pituitary responsiveness to LH-RH correlates positively with basal LH and oestrogen levels during the menstrual cycle and with the oestrogen:progesterone ratio during the luteal phase.
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Acta endocrinologica · Mar 1975
Studies on the inhibitory effect of somatostatin on glucose induced insulin release in the isolated perfused rat pancreas.
Somatostatin, the recently discovered growth hormone release-inhibiting hormone in the hypothalamus, also inhibited glucose induced insulin release from the isolated perfused rat pancreas. The lowest effective dose of somatostatin was 1 ng/ml of perfusate. By increasing the dose to 100 ng/ml an almost complete inhibition of basal as well as stimulated insulin release was obtained. The inhibition of glucose stimulated insulin release mediated by somatostatin might be of competitive nature since somatostatin seemed to dislocate the glucose-insulin dose-response curve to the right.