Figure 6. Role of the pineal gland in cocaine-induced locomotor activity. A-D) Experiment 3: Effect of pinealectomy on cocaine-induced locomotor activity at ZT4, ZT10, ZT16, and ZT22, respectively. E-H) Experiment 4: Effect of melatonin on cocaine-induced locomotor activity at ZT4, ZT10, ZT16, and ZT22, respectively. I-L) Experiment 5: Effect of luzindole on cocaine-induced locomotor activity in animals treated with melatonin at ZT4, ZT10, ZT16, and ZT22, respectively.