Influence of chronic morphine exposure on serum LH, FSH, testosterone levels, and body and testicular weights in the developing male rat

Opiate abuse has been a matter of serious concern in male adolescents. This study investigates the effects of chronic morphine administration on serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone levels, testicular histology, and body and testes weight in developing mal e rats. Animals were subcutaneously injected with morphine (5 mg/kg) or sal ine (1 mL/kg) twice daily for 30 days. Body weight determinations and injec tions were carried out under light ether anesthesia. At the end of the expe riments, the rats were decapitated and blood samples were collected. Serum levels of LH and FSH were measured. Chronic morphine administration signifi cantly decreased serum testosterone (p <.02) and LH (p <.01) levels, but no t FSH release compared to controls. Morphine exposure reduced body weight ( p <.01), but bad no significant effect on the testicular weight. When the t esticular tissue was histologically examined, structural features of the se miniferous tubules and Leydig cells were similar in both saline and morphin e-treated animals. The results suggest that opiates affect testosterone rel ease through the hypothalamo-hypophyseal-gonadal axis rather than by a loca l testicular mechanism. Chronic morphine exposure during sexual maturation may have long-term endocrine disturbances in male rats.