Effect of chronic trifluoperazine administration and subsequent withdrawal on the production and persistence of perioral behaviours in two rat strains.

The effect of chronic administration of trifluoperazine on the perioral movement profile of Wistar and Sprague-Dawley rats was examined. Perioral movements were characterised by visual observations, coupled with electromyographic recording from the masseter muscle. In drug-naive animals from both strains the spectrum of perioral behaviours was essentially identical, primarily consisting of purposeless chewing, accompanied by occasional bursts of facial tremor and teeth chattering, with occasional yawning. Each burst of facial tremor was accompanied by a transient increase in the rate of purposeless chewing. Wistar rats exhibited a higher level of spontaneous purposeless chewing compared to Sprague-Dawley rats. In both strains, chronic administration of trifluoperazine (5 mg/kg per day, PO) for 5 months induced an increase in perioral behaviour, which primarily consisted of enhanced purposeless chewing. In Wistar rats the drug-induced increase in purposeless chewing was accompanied by an increase in the incidence of yawning, with no change in the incidence of either facial tremor or teeth chattering. In contrast, Sprague-Dawley rats displayed a drug-induced increase in purposeless chewing, accompanied by an increase in the incidence of facial tremor and teeth chattering, but not yawning. In Wistar rats withdrawal of trifluoperazine diminished but did not reverse the drug-induced increase in purposeless chewing. Drug withdrawal also precipitated a transient increase in the incidence of facial tremor and teeth chattering, but had no effect on yawning. In Wistar rats, the level of purposeless chewing and the incidence of yawning remained elevated above control levels for at least 13 weeks after drug withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)