Influence of sildenafil on central dopamine-mediated behaviour in male rats.
Two experiments were performed to evaluate the effects of sildenafil on spontaneous or dopamine agonist-induced behaviour in male rats. Data obtained in experiment 1 show that oral administration of the drug, at 1 mg/kg, significantly increased the occurrence of penile erections, anogenital self-grooming and homosexual mounting in grouped sexually-experienced, but not inexperienced, animals. In experiment 2, pre-treatment with sildenafil (0.5, 1 or 10 mg/kg) dose-dependently modified several behavioural signs, centrally evoked by the D2/D3 dopamine agonists, 7-OH-DPAT or B-HT 920 (both at 0.1 mg/kg), in experimentally naive male rats. While sildenafil at 1 mg/kg significantly increased the number of penile erection and stretching-yawning episodes induced by 7-OH-DPAT or B-HT 920, at 10 mg/kg it elicited low stereotyped behaviour, antagonizing stretching-yawning and sedation in 7-OH-DPAT treated rats. Discussion centres on the modulatory activity of sildenafil on central dopaminergic pathways and, possibly, on nitric oxide production.
Ferrari
F
F
Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy.
Ottani
A
A
Giuliani
D
D
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000284:Administration, Oral; D000818:Animals; D001381:Azepines / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D010052:Ovariectomy; D010410:Penile Erection / Q000187:drug effects; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D011687:Purines; D051381:Rats; D017208:Rats, Wistar; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D000068677:Sildenafil Citrate; D013239:Stereotyped Behavior / Q000187:drug effects; D013450:Sulfones; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*
D001381:Azepines; D018491:Dopamine Agonists; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D013764:Tetrahydronaphthalenes; C024763:talipexole; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases; C031349:7-hydroxy-2-N,N-dipropylaminotetralin