DIFFERENTIAL-EFFECTS OF SCH-23390 ON IMMOBILITY BEHAVIORS IN DEVELOPING RATS

The effects of a single injection of a dopamine D1 antagonist, SCH 233 90, at doses of 0, 0.05, 0.1, and 0.2 mg/kg on three different kinds o f immobility behavior were tested in rats of 10, 15, 20, and 30 day of age. Each animal was tested for the dorsal immobility response (DIR), vertical cling catalepsy, and bar catalepsy. A different pattern of r esults was found for each of the three immobility behaviors. SCH 23390 significantly increased the DIR at each age except 15 days; there was a progressive increase in effect from 10 to 20 to 30 days of age. At the lowest dose, drug-induced bar catalepsy peaked at 15 days of age a nd declined at 20 and 30 days of age. The effect of SCH 23390 on verti cal cling catalepsy increased with age, plateauing at 20 days. Thus, t he developmental pattern of immobility responses to this dopamine D1 a ntagonist differs with each behavior measured. (C) 1993 John Wiley & S ons, Inc.