Remodeling The Dendritic Spines In The Hindlimb Representation Of The Sensory Cortex After Spinal Cord Hemisection In Mice

Background:Spinal cord injury (SCI) can induce remodeling of multiple levels of the cerebral cortex system especially in the sensory and motor cortices.Objective:The aim of this study was to assess, in vivo and bilaterally, the remodeling of dendritic spines and axonal boutons in the hindlimb representation of the sensory and motor cortices after spinal cord hemisection.Methods:40 Thyl-YFP transgenic mice were randomly divided into two big groups: the group of sensory cortex and the group of motor cortex. Both the big groups were randomly divided into two groups:the control group and the SCI group, and the spinal vertebral plates (T11-T12) of all mice were excised. Next, the left hemisphere of the spinal cords (T12) were hemisected in the SCI group. The hindlimb representations of the sensory or motor cortex in both groups were imaged bilaterally on the day before, three days (3d), two weeks (2w), and one month (1m) after the SCI. The rates of stable, newly formed, eliminated spines and axonal boutons (motor cortex) were calculated by comparing images of individual dendritic spine and axonal bouton (motor cortex) in the same areas at different time points.Results:In comparison to the control group, the rate of newly formed spines in the contralateral sensory cortex of the SCI group increased at three days and two weeks after the SCI. The rates of eliminated spines in the bilateral sensory cortices increased and the rates of stable spines in the bilateral cortices decreased at two weeks and one month. From three days to two weeks, the survival rates of stable spines in bilateral...