ANXIOGENIC BEHAVIOR IN THE LIGHT-DARK PARADIGM FOLLOWING INTRAVENTRICULAR ADMINISTRATION OF CHOLECYSTOKININ-8S, RESTRAINT STRESS, OR UNCONTROLLABLE FOOTSHOCK IN THE CD-1 MOUSE

The influence of restraint stress (0, 15, 30, or 60 min), uncontrollab le footshock (0, 15, 30, or 60 shocks), or intraventricular CCK-8S adm inistration (0, 5, 25, or 50 ng delivered in a 1 mu l volume) were eva luated on transition frequency and cumulative time in light among CD-1 mice in the light-dark paradigm. Mice exposed to restraint stress of either 15 or 60 min were indistinguishable from nonrestrained animals, while the 30-min session of restraint decreased time in light and tra nsition scores. The presentation of 15, 30, or 60 uncontrollable foots hocks were equally effective in decreasing cumulative time in light bu t had no effect on transition scores. Intraventricular infusion of 25 and 50 ng doses of cholecystokinin-8S reduced cumulative time in light and transition frequency in CD-1 mice relative to vehicle or 5 ng CCK -8S-treated animals in the light-dark paradigm. The time in light and transition data secured among mice with repeated light-dark exposure a nd 30 min of restraint were comparable to the corresponding scores sec ured when performance was only evaluated on trial 1. Transition scores were reduced on trial 1 of mice exposed to 30 min of footshock, but t ime in light was reminiscent of the performance detected among mice wi th prior light-dark experience. Potential neurochemical correlates ass ociated with the anxiogenic effects associated with stressor exposure and CCK-8S administration in the light-dark task are discussed. (C) 19 97 Elsevier Science Inc.