ASYMMETRY IN BEHAVIORAL-RESPONSES TO CHOLECYSTOKININ MICROINJECTED INTO RAT NUCLEUS-ACCUMBENS AND AMYGDALA

The behavioral responses of rats to uni- or bilateral microinjections of the octapeptide cholecystokinin (CCK-8) into the left and/or right or both nucleus accumbens (NA) or amygdalae were studied. There were t wo main findings of effects of microinjections of CCK-8 into NA. First , bilateral injections of CCK-8 into NA dose-dependently decreased the horizontal activity. The second more important finding was that CCK-8 at a specific dose (0.01 mu g) injected into the right NA increased t he number of horizontal movements 6-fold as compared to the injection into the left NA. Neither uni- nor bilateral injections of CCK-8 into NA at all doses used induced changes in the vertical movements. CCK-8 injected into left, right or both amigdalae increased locomotion at th e lowest dose (0.01 mu g), while at the high doses (0.5 and 1.0 mu g) it significantly decreased it. The plus-maze test confirmed the anxiog enic effect of CCK-8 (0.01 mu g) injected into amigdalae. CCK-8 exerte d a favorable effect on learning and memory (shuttle-box) when injecte d into the left but not into the right amygdala. Injection of CCK-8 (0 .01 mu g) into left amygdala provoked a 4-fold increase of the number of avoidances as compared to the microinjection into the right amygdal a.