Seizures elicited by subcutaneous injection of metrazol during ontogenesis in rats.

Metrazol administered subcutaneously at a dose of 80 mg . kg-1 elicited genuine minimal seizures (predominantly clonic) in adult, 45- and 25-day-old rats. The same dose of metrazol resulted in long-lasting generalized tonic-clonic seizures in rats aged 15 days and younger. Eighteen-day-old rats represented a transitory stage in which both types of seizures were present: minor seizures at first and then, after a short resting period, major seizures. A different seizure pattern in young rats was not induced by their higher sensitivity to metrazol, but was caused by the level of neural maturation.