Anticonvulsant action of a NMDA receptor antagonist CGP 40116 varies only quantitatively during ontogeny in rats.

Anticonvulsant action of CGP 40116, a competitive antagonist of N-methyl-D-aspartate type of excitatory amino acid receptors, was studied in rats during development (7, 12, 18, 25 and 90 days old). Two types of motor seizures were elicited by a subcutaneous injection of pentylenetetrazol. Pretreatment with CGP 40116 did not influence minimal, predominantly clonic seizures in any age group. Generalized tonic-clonic seizures were at first modified--their tonic phase was restricted to forelimbs, then selectively suppressed--and with increasing dosage the clonic phase was blocked too. This effect exhibited only minor quantitative changes during development.