Effects of prolactin on aldosterone secretion in rat zona glomerulosa cells

Acute effects and action mechanisms of prolactin (PRL) on aldosterone secretion in zona glomerulosa (ZG) cells were investigated in ovariectomized rats. Administration of ovine PRL (oPRL) increased aldosterone secretion in a dose-dependent manner. Incubation of 3H]-pregnenolone combined with oPRL increased the production of 3H]-aldosterone and 3H]-deoxycorticosterone but decreased the accumulation of 3H]-corticosterone. Administration of oPRL produced a marked increase of adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in ZG cells. The stimulatory effect of oPRL on aldosterone secretion was attenuated by the administration of angiotensin II (Ang II) and high potassium. The Ca2+ chelator, ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA, 10(-2) M), inhibited the basal release of aldosterone and completely suppressed the stimulatory effects of oPRL on aldosterone secretion. The stimulatory effects of oPRL on aldosterone secretion were attenuated by the administration of nifedipine (L-type Ca2+ channel blocker) and tetrandrine (T-type Ca2+ channel blocker). These data suggest that the increase of aldosterone secretion by oPRL is in part due to (1) the increase of cAMP production, (2) the activation of both L- and T-type Ca2+ channels, and (3) the activation of 21-hydroxylase and aldosterone synthase in rat ZG cells.