Effect of haloperidol withdrawal on motor activity and circadian rhythm of rats.

The influence of haloperidol withdrawal on motor activity and circadian rhythm was observed in rats. Haloperidol was administered with the food at a concentration of 0.005%. Motor activity was recorded for 2 days on normal food, for 4 days on food with haloperidol addition and for another 5 days on normal food again in two groups of four rats each. Withdrawal of haloperidol raised the peak values during both phases impressively. The highest activity was observed on the day of haloperidol withdrawal but subsided again on the fifth day. The circadian rhythm remained unchanged.