Alterations in spermatogenic activity and hormonal status in a seasonally breeding rat, Rattus fuscipes.
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Androgens↗
Biomedical subjects
G T Whipp
Publications and source records attributed to G T Whipp.
Regulation of aldosterone in the rat. Effect of oestrous cycle, pregnancy, and sodium status.
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Aldosterone↗
Regulation of aldosterone in the guinea-pig--effect of oestrus cycle, pregnancy and sodium status.
The blood concentrations of aldosterone, corticosterone and cortisol were measured in conscious, non-stressed guinea-pigs using a double isotope dilution derivative assay procedure. Aldosterone levels in the guinea-pig were high when compared with those of other species. The concentration of aldosterone, 37-7 +/- 15-9 ng/100 ml (x +/- SD), and cortisol, 31-8 +/- 10-1 mug/100 ml, found in non-pregnant females on a moderate sodium intake was significantly greater than in males (aldosterone 22-2 +/- 2-4 ng/100 ml and cortisol 19-3 +/- 5-7 mug/100 ml). There was no sex difference in corticosterone concentrations; females, 0-25 +/- 0-06 mug/100 ml and males, 0-23 +/- 0-10 mug/100 ml. The oestrus cycle had no effect on levels of the three steroids measured. Two thirds of the way through the 68-day gestation period aldosterone levels were significantly elevated compared with non-pregnant values (68-7 +/- 50-9 ng/100 ml, p less than 0-05). Values at day 20 (33-2 +/- 11-7 ng/100 ml) and day 60 of gestation (51-9 +/- 21-7 ng/100 ml) were similar to those of non-pregnant animals. Cortisol and corticosterone levels were significantly elevated at 20 days gestation and they continued to rise until, at day 60, cortisol was 9 times and corticosterone 4 times higher than the non-pregnant values. Compared with a moderate Na intake, salt loading suppressed aldosterone levels and Na restriction raised them.
Aldosterone↗
The ontogeny and regulation of corticosteroid secretion by the ovine foetal adrenal.
Adrenal glands of foetal sheep of 40 days gestation to term were incubated with and without ACTH or an increased [K-+]. With ACTH, the 40 day foetal adrenal was capable of producing more cortisol and aldosterone per g body weight than was the term adrenal. ACTH was a potent stimulus to aldosterone and cortisol production in foetuses aged 60-90 days, and this effect declined significantly in the 91-120 day period. An increased [K-+] was stimulatory to aldosterone production only after 120 days gestation. Peripheral blood levels of aldosterone, corticosterone, cortisol, 11-deoxycortisol and 11-deoxycorticosterone were measured in foetuses 60 days to term and the levels of aldosterone and cortisol were significantly lower in 90-120 day foetuses than in the younger or older ones. Direct adrenal vein cannulation proved all five steroids to be secretory products of the foetal adrenal.
Adrenal Glands↗
The effect of pregnancy on mineralo- and gluco-corticoid secretion in the sheep.
1. The peripheral blood concentrations of aldosterone, corticosterone and cortisol were measured during pregnancy in conscious, undisturbed sheep. 2. Aldosterone levels did not change during pregnancy and the mean pregnant value, 1-2 s.d. 1-4 ng/100 ml(n = 12) was not significantly different from the non-pregnant value, 2-1 s.d. 1-7 (n = 16). 3. Cortisol levels likewise were unchanged by pregnancy-non-pregnant values were 0-56 s.d. 0-50 mug/100 ml (n = 12) compared with 0-46 s.d. 0-40 mug/100 ml (n = 16) in pregnant sheep. 4. Sheep of 110-140 days gestation had a 400 mmol greater total exchangeable sodium than non-pregnant sheep. Plasma volume and plasma renin concentration tended to be elevated near to term. 5. Very high aldosterone secretion rates and peripheral blood levels could be produced in pregnant sheep by stress, intravenous ACTH or angiotensin II infusions, and by sodium deficiency. It is suggested that the pregnant sheep may show increased sensitivity in contrast to non-pregnant sheep to these stimuli and the enlarged size of their adrenals may be a contributing factor.
Adrenocorticotropic Hormone↗