Circadian fluctuations were measured in the head twitch response produced by 5-methoxy-N1,N1-dimethyltryptamine (5-MeODMT) and p-chloroamphetamine (PCA) in male BK. TO mice. The effects of depleting brain 5-hydroxytryptamine (5-HT) with p-chlorophenylalanine (PCPA) on the 5-MeODMT in the mouse were also studied. Changes in brain 5-HT and 5-hydroxyindoleacetic (5-HIAA) were concomitantly...