The selective serotonin reuptake inhibitor fluvoxamine suppresses post-feeding hyperactivity induced by food restriction in rats

Previous studies demonstrated that rats allowed access to running wheel with food restriction schedules run excessively. This hyperactivity consisted of a pre-feeding activity (an increase in running activity before the feeding time, also termed food-anticipatory activity: FAA) and a post-feeding activity (an increase in running activity after the feeding time, succeeding activity: SA). Here we evaluated the effect of fluvoxamine, a selective serotonin reuptake inhibitor, on food restriction-induced hyperactivity in rats. Furthermore, the effect of fluvoxamine on each of the FAA and the SA was also investigated. Rats were individually housed in a running-wheel cage under food restriction for 3 h per day, and running activity was measured for 7 consecutive days. This restricted feeding significantly increased the running activity and decreased body weight. Simultaneous administration of fluvoxamine (50 mg/kg/day, p.o.) for 7 days suppressed the increase in running activity (P < 0.05) with no modification of the decrease in body weight or food intake. Analysis of each activity revealed that fluvoxamine's efficacy was observed only in the SA (p < 0.01). These results suggest that repeated treatment with fluvoxamine attenuates the hyperactivity, which is exclusively dependent on the substantial reduction in the SA.