PARENT SESSION
Gonadal Steroids

EFFECTS OF TESTOSTERONE ON THE PRODUCTION OF ALDOSTERONE IN RAT ZONA GLOMERULOSA CELLS.

Lee, Hsaio-Wei¹, Kau, Mei-Mei^2,1, Tseng, Yi-Ching¹, Wang, Paulus¹, ^{1 2}

ABSTRACT- We previously found that administration of testosterone (T, 1-100 nM) dose- dependently decreased the production of aldosterone (A) by the adrenocortical cells of intact male rats. However, the role and mechanisms of T in regulating the production of A in castrated rats are not clear. In the present study the effect of T replacement in castrated rats on the production of A by rat zona glomerulosa (ZG) cells in vitro was examined. Male rats were orchidectomized (Orch) for two weeks and then subcutaneously (sc) injected with testosterone propionate (TP, 0.2 mg/kg body weight) daily for one week before decapitation. TP was dissolved in sesame oil. The control animals were sc injected with sesame oil. Rat ZG cells (100000 cells/ml) were prepared and incubated with or without angiotensin II (100 nM), A23187 (a calcium ionophore, 10 M), cyclopiazonic acid (CPA, an activator of intracellular calcium release, 10 M), corticosterone (substrate of aldosterone synthase, 1 M) or TP (10~100 nM) at 37 C for 1 h. At the end of incubation, the medium was collected and the concentration of A was measured by RIA. The production of A in vitro in rat ZG cells was enhanced (p<0.01) by administration of angiotensin II, A23187, CPA and corticosterone. The production of A in vitro by ZG cells of oil-injected Orch rats was decreased by administration of 100 nM TP, but unaffected by 10 nM TP. Compared with oil-injected Orch rats, replacement of TP in vivo resulted in an increase of the basal release of A by 103± 5 % (p<0.01), and the release of A in vitro in response to angiotensin II (42± 11 %, p<0.01), A23187 (142± 23 %, p<0.01), CPA (53± 18 %, p<0.05), and corticosterone (54± 10 %, p<0.01). These results suggest that testosterone in vivo increases aldosterone production by an indirect action on rat ZG cells via a mechanism in part involving an increase of the intracellular calcium and the activity of aldosterone synthase.

KEY WORDS: Aldosterone, Testosterone, ZG cells, Rat