¹Groupe de Recherche en Urologie, UPRES, 1602 EA, Medical University of Paris South, France

²PELVIPHARM Laboratories, Domaine INRA, rue de la Guyonnerie, 91440 Bures-sur-Yvette, France

³Laboratoire de Neurobiologie des Fonctions Végétatives, Institut National de la Recherche Agronomique, 78352 Jouy-en-Josas Cedex, France

Correspondence to: F Giuliano, Department of Urology, CHU de Bicêtre, 78 rue du Général Leclerc, 94270 Le Kremlin Bicêtre Cedex, France. E-mail: giuliano@cyber-sante.org

Considering the presence of dopaminergic receptors in the lumbosacral spinal cord, we tested whether apomorphine could exert a proerectile effect by acting at the spinal level. Intracavernous (ICP) and blood pressures (BP) were measured in anesthetized rats. ICP rises were quantified (duration, percentage of ICPmaximum/meanBP (ICPmax/BP´100), area under ICP curve (AUC/BP) and sum of AUC/BP after intravenous (i.v.) and intrathecal (i.t.) injections of apomorphine alone or in presence of i.t. oxytocin (10 ng). Both 10 and 30 µg i.v. apomorphine dosings elicited erectile events evidenced by ICP rises. Upon the 30 µg i.v. injection, duration of ICP rises were increased from 25±10 to 69±18 s (P<0.001), ICPmax/BP´100 from 21±3 to 50±14% (P=0.001), AUC/BP from 3±1 to 14±6 s (P=0.002) and sum of AUC/BP from 5±7 to 34±35 s (P=0.021). Upon 30 µg i.t. injections of apomorphine at the lumbosacral level, the number of ICP rises was increased from 0.2±0.4 to 3.0±1.5, ICPmax/BP´100 from 16±9 to 43±12 and sum of AUC/BP from 1±3 to 31±15 s compared to vehicle injection (P<0.05 for all parameters). Injection of 30 µg i.v. or i.t. apomorphine non-significantly enhanced the number and amplitude of the ICP rises induced by 10 ng i.t. oxytocin. However, the enhancement of the amplitude of the ICP rises elicited by i.t. oxytocin was more pronounced with i.t. apomorphine than with i.v. apomorphine. These results suggest the existence of a spinal site of action for apomorphine which may (1) participate to generation of erection and (2) exerts a facilitator effect on erection of supraspinal origin.

International Journal of Impotence Research (2001) 13, 110-115

apomorphine; erection; spinal cord; rat