Changes of ultrastructure in the hippocampal dentate gyrus in rat models of vascular dementia

Objective To observe the ultrastructure changes of hippocampal dentage gyrus (DG) and spatial learning and memory ability changes in rats models of vascular dementia (VD), and investigate the relationship between them. Methods Twelve adult male SD rats were randomly divided into sham-operated group and VD model group (n=6); the VD rat models were prepared by improved permanent bilateral carotid occlusion. The spatial learning and memory abilities of rats were assessed by Morris water maze (MWM), and the ultrastructures of DG were detected by transmission electron microscope. Results (1) In the place navigation trial of MWM, the mean escape latency in VD group was significantly longer than that in sham-operated group (P<0.05); in the spatial probe trial, the number of platform crossings in VD group was markedly smaller as compared with that in sham-operated group (P<0.05). (2) The changes in ultrastructures of hippocampal DG in VD rats were as follows: the number of synaptic vesicles was reduced; the rough endoplasmic reticulum was reduced and arranged in disorder, and free ribosome was increased; the membrane and cristae of mitochondria in the synaptosoma were blurred, and the cristae was fractured; the synaptic cleft was blurred. Conclusion The spatial learning and memory disabilities in VD rats may be associated with injury of ultrastructures in hippocampal DG. Key words: Vascular dementia; Hippocampal dentate gyrus; Morris water maze; Ultrastructure