EFFECTS OF ACUTE HALOPERIDOL AND RESERPINE ADMINISTRATION ON VACUOUS JAW MOVEMENTS IN 3 DIFFERENT AGE-GROUPS OF RATS

In these experiments three different age groups of rats were tested fo r vacuous jaw movements. The age groups included rats aged 3 months, r ats aged 6-9 months, and rats aged 12-15 months. In the first experime nt, rats were given a single IP injection of either 0.3% tartaric acid vehicle or 0.4 mg/kg haloperidol. In the second experiment, rats were given injections of vehicle or 5.0 mg/kg reserpine. Haloperidol and r eserpine significantly increased vacuous jaw movements. There were sig nificant effects of age on vacuous jaw movements, with rats aged 6-9 m onths and rats aged 12-15 months showing more jaw movements than 3-mon th-old rats. In both experiments, the drug X age interaction was not s ignificant, indicating that the combined effects of age and neurolepti c treatment were additive and not synergistic. Haloperidol and reserpi ne also reduced rearing behavior in all age groups. It is concluded th at age is an important variable in studies of vacuous jaw movements.