Postnatal development of a cholinergic influence on neuroleptic-induced catalepsy.

The development of cholinergic influence on neuroleptic-induced catalepsy was investigated in 10-, 15- and 20-day-old rat pups. It was found that the antimuscarinic atropine was ineffective in decreasing the catalepsy produced by spiroperidol treatment at 10 and 15 days. By day 20, however, atropine attenuated cataleptic behavior in a dose-dependent manner. Atropine alone was shown paradoxically to elicit mild to moderate cataleptic responses in 10- and 15-day-olds, but not at day 20. Clozapine by itself produced the same age dependent pattern of catalepsy response as the spiroperidol and atropine combination treatment. These results suggest that cholinergic mechanisms which interact antagonistically with the dopamine systems underlying cataleptic behavior are not functionally mature until after day 15 in the rat.