Influence of sildenafil on copulatory behaviour in sluggish or normal ejaculator male rats: a central dopamine mediated effect?
The present study investigates the effects induced by sildenafil (1 mg/kg, p.o.) and the dopamine agonist, SND 919 (0.1 mg/kg, i.p.) on copulatory behaviour of male rats, categorized, on the basis of seven consecutive mating pre-tests, as sluggish and normal ejaculators (SE and NE, respectively). The data obtained show that sildenafil modifies both sexual arousal and ejaculatory mechanisms of copulation. It appears that, although it induced a facilitatory effect on ejaculation of all rats, similarly to SND 919, the lowering of ejaculatory threshold was achieved by means of a reduction of mount frequency and intromission frequency in SE and NE groups, respectively. Differently from SND 919, sildenafil increased sexual arousal, diminishing post ejaculatory interval in SE animals and inter-intromission interval in both SE and NE rats. As the dopamine antagonist, (-)eticlopride (0.02 mg/kg, s.c.), significantly inhibited sildenafil-induced enhancement of sexual arousal in SE rats, it is suggested that the drug acts both peripherally and centrally.
Giuliani
D
D
Department of Biomedical Sciences, Division of Pharmacology, University of Modena and Reggio Emilia, via G. Campi 287, 41100, Modena, Italy.
Ottani
A
A
Ferrari
F
F
D000818:Animals; D052160:Benzothiazoles; D003307:Copulation / Q000187:drug effects* / Q000502:physiology; D018491:Dopamine Agonists / Q000494:pharmacology; D004542:Ejaculation / Q000187:drug effects* / Q000502:physiology; D005260:Female; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010879:Piperazines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000077487:Pramipexole; D011687:Purines; D051381:Rats; D017208:Rats, Wistar; D012457:Salicylamides / Q000494:pharmacology; D000068677:Sildenafil Citrate; D013450:Sulfones; D013844:Thiazoles / Q000494:pharmacology
D052160:Benzothiazoles; D018491:Dopamine Agonists; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D012457:Salicylamides; D013450:Sulfones; D013844:Thiazoles; D000077487:Pramipexole; D000068677:Sildenafil Citrate; C045989:eticlopride