Effects of single and long-term droperidol administration on open-field and stereotyped behavior of rats.

The effects of single and long-term droperidol administration on rat open-field and apomorphine-induced stereotyped behavior were studied. A single dose of droperidol decreased dose dependently not only locomotion and rearing frequencies in the open-field but also the apomorphine effects. Long-term droperidol administration induced significant tolerance to all parameters of activity recorded in the open-field. Unlike other dopamine blockers, droperidol withdrawn from long-term droperidol administration wasn't able to increase rats' open-field parameters significantly. However, like other dopamine blockers, droperidol withdrawn produced an augmented responsiveness to apomorphine-induced stereotyped behavior. These results suggest that the supersensitivity of central dopamine receptors developed after droperidol treatment may have peculiar characteristics.