Toxic effects of the antifertility agent gossypol in male rats

In the present investigation the influence of gossypol on the male sex function and toxicology in the rat have been studied. Gossypol was injected daily for 5 weeks to adult male rats of the Sprague-Dawley strain with 1 or 10 mg/kg body wt. The low dose of gossypol (1 mg/kg body wt.) did not have any effect on the following parameters: plasma testosterone concentrations, body growth, kidney weights, sex organ weights (ventral prostate, seminal vesicle, epididymis), testicular weights, blood flow to testes, epididymides and ventral prostate as measured with the microsphere technique, intraarterial blood pressure and morphology of testis and epididymis. The plasma testosterone response to acute LH-injection was not significantly different in gossypol-treated rats when compared to control rats. The high dose of gossypol (10 mg/kg body wt) caused signs of tubular degeneration, retarded body growth, markedly reduced testosterone concentrations, involutions of the ventral prostate and seminal vesicles and gastrointestinal disturbances. After 5 weeks of treatment the mortality rate was 13%. It is concluded that gossypol is a very toxic substance in rats, since only a 10-fold increase of a non-effective dose caused serious side effects in addition to its antifertility effects.