Pentylenetetrazol-induced spike wave discharges in rats: a polygraphic study.

14 male Wistar rats were studied, before and after pentylenetetrazol (PTZ) 20 mg/kg i.p., since a petit mal-like electroclinical pattern, either spontaneous or PTZ-induced was recently described in a breeding station where this strain is raised. In particular, surface EEG, muscular, respiratory and cardiac activities were recorded in order to detect possible clinical-electroencephalographic correlations. Spontaneous epileptic phenomena were never observed. In all the animals PTZ-induced short, usually generalized and synchronous spike wave discharges often concomitant with rhythmic twitches of the vibrissae. Epileptic bursts were related to arousal level, disappearing during motor behavior and arousing stimuli. Moreover individual discharges could be interrupted by a sudden noise. Photosensitivity was not present. Muscular tone and autonomic functions were not affected. The features of PTZ-induced generalized nonconvulsive seizures in rats are compared to those of cat penicillin epilepsy and human petit mal.