NEUROLEPTIC-INDUCED DEFECATION IN RATS AS A MODEL FOR NEUROLEPTIC DYSPHORIA

Two groups of 32 rats were challenged in a well-habituated environment with haloperidol (0.5 mg/kg), haloperidol (0.1 mg/kg), domperidone (0 .1 mg/kg), or saline to study the effect of these drugs on defecation- an index of emotionality and voluntary movements in the 2 hours after the injection. The haloperidol-treated rats in the high-dose condition had significantly more bolus counts in the 2 hours after the injectio n than were observed in the groups treated with domperidone (a periphe ral dopamine D2 receptor antagonist) or placebo. All movements were gr eatly reduced in the haloperidol-treated rats and, in this group, the ones with more bolus counts did not differ in their activity levels fr om those with fewer bolus counts. There was a trend for the rats that were less mobile at 10 minutes after the injection to produce more bol i in the 2-hour period. Our study, therefore, replicates the findings of Sanberg (1980) and Russell et al. (1987a, 1987b) that haloperidol i ncreases ''emotional'' defecation in rats in well-habituated environme nts, but the same model does not replicate the motor component of neur oleptic-induced akathisia seen in human subjects.