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ABSTRACT
Because human adrenocortical cells from different adrenal disorders exhibit pathologically altered corticosteroid synthesis, and free radical mechanisms may induce pathological changes in the activities of corticosteroid biosynthetic enzymes (cytochrome P-450), we examined the effect of an antioxidant, silibinin, on basal and ACTH-stimulated secretion of several corticosteroids in isolated adrenal cells from an aldosterone-producing adenoma, atrophied adrenal tissues surrounding the adenoma, and hyperplastic adrenals from Cushing's syndrome. In the presence of a high concentration (100 μmol/l) of silibinin, variably diminished secretion of basal aldosterone, corticosterone, cortisol, 18-OH-corticosterone and 11-deoxycorticosterone was found. In contrast, the addition of 0·01 μmol silibinin/l, which failed to produce a clear effect on basal corticosteroid secretion, resulted in a potentiation of ACTH-stimulated secretion of several corticosteroids in the adenomatous and hyperplastic adrenocortical cells. These results suggest that the dose-dependent dual effect of silibinin on corticosteroid secretion may be attributed to corresponding changes in the activities of cytochrome P-450 enzymes, and that stimulation of ACTH-induced corticosteroidogenesis by silibinin is presumably due to the antioxidant property of the drug.
Journal of Endocrinology (1990) 124, 341–345
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Histamine is synthesized in cells by histidine decarboxylase (HDC). HDC-deficient knockout (KO) mice lack functional HDC and histamine in the tissues. In the present study we used this in vivo model for studying the role of HDC deficiency in the regulation of male steroid hormone metabolism. In agreement with earlier studies showing the lack of effects of central histamine on the basal secretion of gonadotrope hormones, we found no difference with in situ hybridization in the expression of GnRH in the hypothalamus of wild type and KO mice. The tissue concentrations of testosterone and several androgenic steroids were significantly elevated in the testes but not in the adrenal glands of HDC-KO mice. In contrast, serum estradiol levels failed to show a significant difference between the two groups. The weight of the testes was significantly smaller in both 7-day-old and adult KO mice. The ultrastructure of the adult testis indicated elevated steroid synthesis with more tightly coiled membranous whorls in Leydig cells. The present results suggest that changes in reproductive functions and sex steroid secretion in male HDC-KO mice are not due to altered hypothalamic GnRH expression but are probably related to definite modifications during fetal development of KO mice reinforced later by the lack of the effect of peripheral histamine. This may provide in vivo evidence that peripheral histamine is an important regulatory factor of male gonadal development during embryogenesis and of sex steroid metabolism later in adulthood.
