LONG-LASTING STRUCTURAL-CHANGES IN CA3 HIPPOCAMPAL AND LAYER-V MOTOR CORTICAL PYRAMIDAL NEURONS ASSOCIATED WITH SELF-STIMULATION REWARDING EXPERIENCE - A QUANTITATIVE GOLGI-STUDY

Self-stimulation (SS) rewarding experience induced structural changes in CA3 hippocampal and layer V motor cortical pyramidal neurons in adu lt male Wister rats has been demonstrated. In the present study, wheth er these structural changes are transient or of a permanent nature was evaluated. Self-stimulation experience was provided for 1 h daily ove r a period of 10 days through bilaterally implanted bipolar electrodes in the lateral hypothalamus and the substantia nigra-ventral tegmenta l area. Following 10 days of SS experience, the rats were sacrificed a fter an interval of 30 and 60 days for the quantitative analysis of th e dendritic morphology in Golgi stained CA3 hippocampal and layer V mo tor cortical pyramidal neurons. The results revealed a significant inc rease in the dendritic branching points and intersections in apical an d basal dendrites in both types of neurons in 30 days post-SS group co mpared to sham control. The total number of apical and basal dendrites were significantly increased in both 30 and 60 days post-SS groups of rats. This study suggests that SS experience induced structural chang es are sustainable, even in the absence of rewarding experience. (C) 1 998 Elsevier Science Inc.