FIG. 4.
Effects of caffeine injections on locomotor activity of mice after chronic caffeine ingestion followed by withdrawal. Locomotor activity was determined after IP injection of vehicle (hatched bars) or 20 mg/kg caffeine (increase over vehicle indicated by open bars) to control mice or chronic caffeiue-treated mice. Chronic ingestion of caffeine was for 5, 14, 21, and 29 days, followed by 2 days of withdrawal. Bars corresponding to chronic caffeine-treated mice are indicated by a star on the x-axis. Each day represents a separate group of mice. Values are means ± SEM. (n = 6–17).