Inhibition of testosterone synthesis by ethanol: Role of luteinizing hormone

Abstract

The effects of acute ethanol intake (1.5 g/kg) on plasma testosterone and luteinizing hormone (LH) concentrations were examined in male Long-Evans rats. Ethanol decreased the serum LH concentrations by 21% and 42% 30 and 60 minutes after ethanol administration respectively. The testosterone concentrations decreased later (30 min: +8%; 60 min; −30%). The LH concentrations were highly correlated with subsequent (60 min later) testosterone concentrations (LH 30min: r = .688, p<0.001, n = 25; LH 60 min: r = .678, p<0.001), but less so with concurrent testosterone concentrations (30 min: r = .187, N.S.; 60 min: r = .552, p<0.004). To further test the influence of LH, naloxone (11 mg/kg) was administered, which elevated the LH levels within 30 min by 103% in controls. Naloxone also increased serum LH concentration by 34% in ethanol-treated rats at 30 min, but these animals nevertheless had lower ( p<0.01) testosterone levels at 60 min than did control animals without naloxone and ethanol treatment. It is concluded that although ethanol-induced changes in serum LH levels may play a role in the decrease of serum testosterone concentrations in rats, there are also other mechanisms by which ethanol may produce these effects.