Effects of MAK on 5-HTP-induced head twitches. Results are the mean ± S.E.M. of the number of head twitches for a 30-min observation period. The number of rats per group was: control group, n = 6; MAK-treated group, n = 6; fluvoxamine-treated group, n = 6. **P < 0.01 compared with the control group, one-way analysis of variance followed by Tukey’s test.