Differentiation of Steroid Metabolism in the Rat and Mechanisms of Neonatal Androgen Action

Sexual dimorphism in adrenal activity appeared during the pubertal period of the guinea-pig with plasma levels and binding of cortisol lower in male guinea-pigs compared with female, and metabolic clearance rate (MCR) of cortisol higher in male than in female animals. Gonadectomy of female guinea-pigs did not change the values of the parameters regulating adrenal activity. Castration of male guinea-pigs caused a rise in plasma cortisol levels by increasing the binding capacity of transcortin for cortisol and by decreasing cortisol MCR. Treatment of females with testosterone from day 24 produced a drop on day 50 in plasma cortisol levels following a decreased binding capacity of transcortin for cortisol and at the same time as cortisol MCR increased. Furthermore, the adrenal response to stress was higher in castrated than in control males and lower in testosterone-treated females compared with control females. Testosterone appeared to be the hormone responsible for sexual dimorphism in adrenal activity in the pubertal guinea-pig.

Section: Discussionmentioning

confidence: 47%

Role of Testosterone in the Sexual Dimorphism of Adrenal Activity at Puberty in the Guinea-Pig

Hani¹,

Dalle²,

Delost³

1980

“…In liver the effect of neonatal intervention is to change both the age-dependent develop¬ ment and sexual differentiation of enzymes of steroid metabolism (see De Moor, Verhoeven & Heyns, 1973;Denef, 1973). Enzyme activities which show an age-dependent development, with or without sexual differentiation, are not only found in liver, but also occur in kidney , adrenal and gonadal tissues (Kitay, 1968;Tamaoki, Inano & Nakano, 1969;Wiest & Kidwell, 1969;Björkhem, Eriksson, Gustafsson, Karlmar & Stenberg, 1972;Ghraf, Vetter & Schriefers, 1974).…”

Section: Introductionmentioning

confidence: 99%

Enzyme Activity in Kidney, Adrenal and Gonadal Tissue of Rats Treated Neonatally With Androgen or Oestrogen

Ghraf¹,

Hoff²,

Lax³

et al. 1975

A single injection of 300 mug oestradiol benzoate (OEB) or 1.25 mg testosterone propionate (TP) on day 1 of life led to significant changes in the activity of enzymes involved in steroid hormone metabolism in kidney, adrenal and gonadal tissues of adult rats. In the kidney, the enzyme activities of male rats reacted to OEB, but not TP, by the development of normal female levels. With one exception the enzyme activities of the kidney of female rats did not respond to either steroid. In the adrenal of both sexes 5alpha-reductase reacted to OEB, but not TP treatment, by a fourfold increase in activity. In the ovary all the enzymes investigated responded both to OEB and TP treatment by a fall in activity; 20alpha-hydroxysteroid dehydrogenase activity fell to undetectable levels. In the testis, OEB and TP treatment led to contrasting effects. With the exception of 5alpha-reductase all the enzymes tested in this organ responded to OEB by a rise in activity. Where TP had any effect, it produced a slight decrease in activity.

“…Investigations of the regulation of the sex differences found in the enzyme activities of hepatic steroid metabolism in the rat have demonstrated both permissive and active involve¬ ment of hypophysial secretions (Colby, Gaskin «fe Kitay, 1973;Denef, 1973Denef, , 1974Gustafsson & Stenberg, 1974;Lax, Hoff, Ghraf, Schröder & Schriefers, 1974;Lax, Ghraf, Schrief¬ ers, Herrmann & Petutschnigk, 1976). The permissive role of the hypophysis is reflected by the fact that administration of sex hormones (testosterone or oestradiol) to gonadectomized rats only causes the expected changes in sex hormone-dependent enzyme activities when the pituitary is intact.…”

Section: Introductionmentioning

confidence: 99%

ENDOCRINE REGULATION OF SEX-DEPENDENT HYDROXYSTEROID DEHYDROGENASE ACTIVITIES IN RAT KIDNEY: NADP-DEPENDENT MICROSOMAL 3α- AND 20β-Hydroxysteroid DEHYDROGENASE

Ghraf¹,

Lax²,

Wagner³

et al. 1977

The NADP-dependent microsomal kidney enzymes, 3alpha- and 20beta-hydroxysteroid dehydrogenase (HSDH), which exhibit considerable sex differences in their activities (male:female activity ratios, 16:1 and 30:1 respectively), were investigated after interference with the pituitary-gonad and pituitary-adrenal systems. Prepubertal gonadectomy as well as hypophysectomy of mature male rats led to a decline in HSDH activity to almost that found in the normal female rat, whereas activities in female rats were unaffected. Testosterone induced typical male 3alpha-HSDH activity in both gonadectomized and hypophysectomized rats of either sex. Administration of 5alpha-dihydrotestosterone (5alpha-DHT) or 5alpha-androstane-3alpha, 17beta-diol to hypophysectomized male rats was equally effective in restoring full 3alpha- and 20beta-HSDH activities whereas 5alpha-androstane-3beta, 17beta-diol was less effective and dehydroepiandrosterone was ineffective. Simultaneous administration of cyproterone acetate did not block the inductive action of 5alpha-DHT. Administration of chorionic gonadotrophin, pregnant mare serum gonadotrophin or a combination of luteinizing hormone and follicle-stimulating hormone to hypophysectomized male rats all led to parallel increases in the weight of the seminal vesicles and in both renal enzyme activities; administration of growth hormone, prolactin or thyroid-stimulating hormone was ineffective. Adrenalectomy of gonadectomized, but not of hypophysectomized male rats, caused a further drop in activity to the normal female level. Adrenalectomy of otherwise intact rats did not affect either enzyme activity. The hypophysis was involved in the regulation of the two NADP-dependent renal HSDH activities through its gonadotrophic function in male rats; adrenal secretions were of little physiological significance.