In order to know the contribution of adrenal and gonadal androgens to the development of the side gland of Suncus murinus, we studied the effects of gonadectomy and adrenalectomy on gland thickness and the plasma levels of testosterone, androstenedione (Δ
4-dione) and dehydroepiandrosterone (DHA). In males, castration decreased gland thickness to 71% of the control. The plasma level of Δ
4-dione and testosterone were also decreased from 4.16±0.50 and 0.65±0.10ng/m
l to 1.44±0.17 and 0.12±0.02ng/m
l, respectively. Adrenalectomy following castration caused no notable additional decrease in gland thickness, although the plasma levels of Δ
4-dione and DHA were further decreased by this treatment. In females, ovariectomy affected neither gland thickness nor plasma androgen levels, except for a peculiar rise in the plasma concentration of Δ
4-dione. In contrast, adrenalectomy in addition to ovariectomy decreased gland thickness to 63% of the control and the plasma concentrations of Δ
4-dione and DHA from 1.43±0.26 and 0.43±0.05ng/m
l to 0.37±0.11 and 0.10±0.04ng/m
l, respectively. Therefore, testicular androgens are required for the male side gland to fully develop, whereas in the female adrenal androgens are important for the maintenance of sebaceous gland activitiy and Δ
4-dione is quantitatively more important than DHA. One hour after the intraperitoneal administration of [
3H]Δ
4-dione, dihydrotestosterone was found to be the major androgen bound to nuclei of the side gland. Thus, the side gland can utilize Δ
4-dione as a precursor of a more active androgen. The side gland seems to be a useful model for understanding the role of adrenal androgens in target tissues.
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