Facilitating effects of some chlorpromazine-D-amphetamine mixtures on avoidance learning

Effects of amphetamine and haloperidol on avoidance behavior and exploratory activity

The effect of graded doses of D-amphetamine and haloperidol were tested on retention of a one trial learning passive avoidance response, on extinction of pole-jumping active avoidance behavior and on open-field activity. Low doses of amphetamine (10 microgram/animal) increased passive avoidance latency when given s.c. 1 h prior to the retention test. Higher doses (20 and 1000 microgram/animal) caused a bimodal distribution of avoidance latencies. Haloperidol (0.03 or 1.0 microgram/animal) significantly attenuated passive avoidance behavior. Amphetamine caused a delay of extinction of pole-jumping avoidance behavior in a dose-dependent manner (10, 30 or 90 microgram per rat). Conversely, haloperidol induced a dose-dependent facilitation of extinction (0.03 or 0.1 microgram per rat). Open-field activity was not significantly affected by 30 microgram amphetamine or 0.03 microgram haloperidol; 90 microgram amphetamine significantly increased rearing activity and 0.1 microgram haloperidol decreased ambulation. The data show that passive and active avoidance behavior are sensitive measures to test the activity of psychomotor stimulant and neuroleptic drugs. Exploratory behavior allows more specific behavioral effects to be dissociated from locomotor influences.

Facilitation of avoidance learning by chlordiazepoxide-amphetamine combinations in mice

Chlordiazepoxide and amphetamine, given separately or in combination, were tested in mice subjected to 5 100-trial avoidance sessions in the shuttle-box. Facilitation of avoidance responding was much more evident and statistically significant when the two drugs were combined. Drug mixtures produced effects which could not be obtained when the drugs were given separately.