The effects of both opiate agonists and the opiate antagonist naloxone
were examined in a rodent model of tardive dyskinesia (TD). Chronic (
approximately 20 weeks) administration of fluphenazine resulted in the
emergence of vacuous chewing mouth movements (VCMs), a response which
may be a useful model for this disorder. Fluphenazine-induced VCMs we
re not affected by a variety of selective opiate agonists administered
intracerebroventricularly, but were potently suppressed by subcutaneo
us administration of the opiate antagonist naloxone. These findings su
ggest that increased opiate transmission may contribute to the pathoge
nesis of TD. Further investigation of the role of opiate antagonists i
n treating this disorder are warranted.