Effects of sildenafil treatment on the development of tolerance to diazepam-induced motor impairment and sedation in mice.

We studied the effects of sildenafil, a selective inhibitor of PDE5, on the development and the expression of tolerance to diazepam (DZ)-induced motor impairment and sedation in mice. DZ-induced motor incoordination was assessed by the rotarod and chimney tests, and DZ-induced sedation was examined using a photocell apparatus. Sildenafil treatment enhanced the development of tolerance to the motor impairing effects, but not to the sedative effects, of DZ. Sildenafil treatment did not affect the expression of tolerance to DZ-induced motor impairment and sedation in mice. Our results suggest that sildenafil treatment, at least in part, affects the development of DZ tolerance.