Cholecystokinin reduces exploratory behavior in mice

The role of cholecystokinin (CCK) in mediating spontaneous behaviors in mice was analyzed, using a video-tracking, computer-assisted animal behavior monitoring system. Intraperitoneal administration of cholecystokinin octapeptide decreased investigation of environmental objects and interactions with a female mouse, while increasing the amount of time spent in the corners of the test arena and the duration of non-exploratory pauses. Dose-dependent effects were seen in the range of 0.12-50 μg/kg. Other parameters of motor activity were normal, indicating that the reduction in exploratory tendencies is not a function of sedation or loss of motor coordination. Neither gastrin nor unsulfated cholecystokinin₈ changed any of the measured parameters, indicating pharmacological specificity for the observed reduction in exploration.