Relationship Between Hippocampal Structure And High Incidence Of Depression After Spinal Cord Injury In Mice

Objective: To explore whether the high risk of depression caused by spinal cord injury is related to changes in hippocampal physiology.Methods: Mouse spinal cord injury model was established;the Basso Mouse Scale(BMS)was used to evaluate the postoperative motor function of mice at different periods after injury;the depression of mice was evaluated by behavior experiment;The weight of the hippocampal tissue was measured;the changes of cells in hippocampal tissue were observed by HE staining;the structural changes of hippocampal subcellular synapses were observed by electron microscope;q RT-PCR was used to detects the changes of synaptic protein markers synaptophysin(SYP)and postsynaptic density protein 95(PSD-95)at the gene level.Results: Behavioral experiments showed that the mice had significant depressive behaviors in the model group,and the depression degree was the most serious on the 7th day(P<0.01);there was no difference in the weight of hippocampal tissue between the control group and the experimental group(P>0.05);HE staining showed that compared with the control group,the arrangement of hippocampal cells was disordered,the number was decreased,and the morphology was irregular in the model group;Compared with the control group,the electron microscope results showed that the number of synapses in the hippocampal ultrastructure was decreased,the length of synaptic activity zone was shorter,the thickness of postsynaptic compacts was thinner,the width of synaptic gap was increased,and the curvature of synaptic interface was decreased in the model group(P<0.05);q RT-PCR results showed that the expression levels of SYP and PSD-95 genes in the model group were lower than those in the control group(P<0.05).Conclusion: The change of hippocampal physiological structure is one of the important reasons leading to high-risk depression caused by spinal cord injury.