ultrastructural study of the impact of Morris water maze spatial learning on synaptic plasticity of rat hippocampal CA1 area

ABSTRACT

The learning procedure leads to biochemical, biophysical and ultrastructural changes in synapses of some specific areas in central nervous system, which is named synaptic plasticity. Material and Twelve male wistar rats were divided in two [case and control] groups. The cases were trained in Morris water maze. The animals underwent 8 training sessions per day, on 3 consecutive days, but the control group did not undergo this training. In the third day all rats were perfused with normal saline and Karnowsky fixator, under deep anesthesia. Then they were decapitated and their brains were enucleated. The CA1 area of dorsal hippocampal formation was punched about - 3.5 to - 4.5mm from Bregma, and the punched pieces were processed for TEM. In comparison with the control group, the case group showed increase in concave synapses, decrease in thickness of postsynaptic density [PSD], vasting of synaptic contact zone [SCZ], formation of perforated postsynaptic density and V- shaped synapses. The results of this study showed that spatial learning leads to a series of ultrastructural changes in synapses of CA1 area of dorsal hippocampal formation which results in enhancement of synaptic efficacy