Plasticity of hippocampal and motor cortical pyramidal neurons induced by self-stimulation experience.

The self-stimulation (SS) induced neuronal plasticity was observed in CA3 hippocampal and layer V motor cortical pyramidal neurons. SS experience was allowed daily for a total of 1 hour for 10 days through four bipolar electrodes implanted bilaterally in lateral hypothalamus (LH) and substantia nigra-ventral tegmental area (SN-VTA) in adult male Wistar rats. Examination of pyramidal neurons stained by rapid Golgi technique was made in a total of 1,600 neurons out of 80 rats consisting of 4 groups. The dendritic intersections were quantified upto 200 and 120 microns radial distances in apical and basal dendrites respectively. The CA3 hippocampal and layer V motor cortical pyramidal neurons of SS group revealed significant increase (P < 0.001, two-way ANOVA) in dendritic intersections in both apical and basal dendrites, compared to normal control (NC), sham control (SH) and experimenter-administered (EA) group of animals. These results demonstrate that SS experience promotes increase in dendritic length in hippocampal and motor cortical pyramidal neurons.