APOMORPHINE VERSUS MATING-BEHAVIOR IN TESTING ERECTILE CAPABILITIES OF DIABETIC RATS

Objectives. Diabetes mellitus (DM) is an important cause of organic impotence. It is estimated that 35% to 75% of diabetic patients are impotent. In the present study we investigated the effect of experimentally induced diabetes (streptozocin 60 mg/kg, intraperitoneally, for 9 weeks) on sexual behavior and compared it to the apomorphine (APO) bioassay test. Methods. Libido, genital refer excitability, and penile competence as measured by different parameters of mating behavior were reduced with DM (P < 0.05 versus control for each parameter). Results. Of 17 diabetic rats, 53% (9 rats) experienced positive mating behavior (either intromission or ejaculation) compared with 82.4% (14 rats) positive response to the APO bioassay test. Moreover, combined apomorphine injection and mating sexual testing in diabetic rats that achieved intromission but not ejaculation or those that did not achieve intromission in the initial mating, considerably improved the performance of these rats. Conclusions. We suggest that the APO test alone or, even better, combined APO injection and sexual testing are superior in eliciting maximum erectile capabilities of the diabetic rats than mating testing alone.