Abstract: Objective To explore the learning and memory impairment and pathology in hippocampus in rats after spinal cord contusion. Methods 36 adult female Sprague-Dawley rats were randomly divided into sham group (n=18) and spinal cord injury group (n=18). Spinal cord injury model at T10 was established with modified Allen's technique (10 g×25 mm). The hindlimbs behavior of rats was rated with Basso-Beattie-Bresnahan (BBB) scores once a week for 5 weeks. They were tested with motor evoked potentials (MEP) and Morris water maze 5 weeks after injury. The pathology of hippocampus was detected with HE staining 1 week, 3 weeks and 5 weeks after injury, 4 rats in a group, repectively. Results The BBB scores were significantly lower in the spinal cord injury group than in the sham group at each time point (P<0.05). The latencies of both N1 and P1 wave of MEP were significantly longer in the spinal cord injury group than in the sham group (P<0.001), while the amplitudes were significantly less (P<0.001). For the Morris water maze, the latency of arrival platform were significantly longer in the spinal cord injury group than in the sham group (P<0.001), and the time in target was significantly less (P<0.001), with more systematic positioning or annular positioning, while the sham group with more space-based positioning. Morphologically abnormal cells in hippocampus gradually increased since the first week after injury, with the decrease of cells survival, while it was normal in the sham group. Conclusion Spinal cord contusion can cause learning and memory impairment in rats, which may be related to injury in hippocampus.

Key words: spinal cord injury, learning and memory, hippocampus, pathology, rats