Interaction of sulpiride with morphine in induction of infertility in male rat

Background and Objective: Male fertility depends on the proper function of a complex system of organs. Harmful effects of morphine on male reproduction and fertility are well documented. Dopamine facilitates sexual behavior in different animal species. Antagonizing of dopamine D2 receptors with sulpiride was aimed to investigate the interaction of dopaminergic system with morphine-induced infertility. Materials and Methods: A total of 48 adult male Wistar rats with a weight range of 220-320 g were used. In the first category, morphine (5 mg/kg) was injected i.p. The next groups received sulpiride (1-4 mg/kg) alone and prior (20 min) to morphine (5 mg/kg). The control group received only saline (1 ml/kg). All rats were sacrificed under deep anesthesia after one week. Their testicles were collected for examination. LH, FSH and testosterone were measured in the sera. Data were analyzed by ANOVA test. Results: Significant decreases in dimensions of testicles were observed in those rats that received morphine or sulpiride prior to the morphine. Seminiferous tube destruction was observed in morphine group and in the group that received sulpiride prior to morphine; destruction was increased with increasing dose of sulpiride. Significant decrease of serum testosterone level was observed in rats receiving morphine and a high dose of sulpiride. Significant increase in serum testosterone level was observed in the group receiving sulpiride prior to morphine. Conclusion: It seems that dopamine has an interacting effect with morphine on induction of male infertility and its mechanism is probably carried out through dopamine D2 receptors.