Effects of apomorphine and diazepam on a quickly learned conditioned suppression in rats.

Electric shock experienced rats exhibited a marked suppression of motor activity when placed in the same environment in which the animal received shocks. At 24 hr after electrical shocks, the shock frequencies of 1/10 Hz to 1/180 Hz equally produced a marked suppression of motility. However, electric shock experienced rats exhibited a similar degree of locomotor activity that was seen with the non-shocked rats, when the motility of the animals was measured by using Animex system at 24 hr after electrical shocks. Therefore, this suppression of motility was found to be a consistent response and to be a conditioned response to the environment. Diazepam (1.2.5 or 5 mg/kg, IP) did not show any effect on the conditioned suppression. Apomorphine-HCl (0.1, 0.5 or 1 mg/kg, IP) caused attenuation of the conditioned suppression in relation to dose, but did not increase motor activity of the non-shocked rats. Thus, conditioned suppression caused by a quick conditioning technique may not be associated with anxiety.