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 two 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 the 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 the 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 anxiogenic effect of CCK-8 (0.01 mu g) injected into amigdalae. CCK-8 exerted a favorable effect on learning and memory (shuttle-box) when injected 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 amygdala.