Effects of alpha-2 blockade on sexual response: experimental studies with Delequamine (RS15385)

The role of alpha-2 receptors and alpha-2 antagonists in central and periph eral mechanisms of sexual response are discussed. It is concluded that the predominant role of the alpha-a antagonist centrally is to increase arousal which in certain circumstances, is sexual. It is further concluded that th e predominant role of the alpha-2 antagonist peripherally is to modulate (b lock) the norepinephrine (NE)-induced contractility in the smooth muscle of the penis. How the central arousal mechanisms are specifically linked to s exual response is not understood. Experimental studies with a selective alpha-2 antagonist, delequamine, are briefly reviewed and their complex results discussed. Evidence from sleep s tudies was consistent with delequamine having both central excitatory and i nhibitory effects, dependent on dosage, The possibility that men with psych ogenic erectile dysfunction might have increased central alpha-2 tone was c onsidered. The apparent loss of responsiveness to the alpha 2 antagonist in older dysfunctional men was discussed. More questions are raised than answ ered; further research is needed in this area.