AIM: To observe the expression change of growth and differentiation factor 10 ( GDF10 ) in the spinal cord of the rats with neuropathic pain .METHODS:Male SD rats (n=60) were used.The neuropathic pain was induced by ligation of left L 5 spinal nerves of the animals .The paw withdrawal threshold was detected 1 d before surgery , and 0 d, 1 d, 3 d, 10 d and 21 d after surgery.The changes of GDF10 in the dorsal horn of L5 spinal cord were detected by immunofluorescence staining and Western blot .RESULTS:The paw withdrawal threshold of the rats with spinal nerve ligation was decreased from 1 d after surgery until 3 d with obvious difference compared with the na ve rats ( P<0.05 ) , continuously decreased until 10 d, and then stabilized at 21 d.The GDF10 was located in the cytoplasm of the neurons in the dorsal horn of L5 spinal cord detected by immunofluorescence staining .The expression of GDF10 in L5 dorsal horn de-tected by immunofluorescence staining was reduced after surgery , significantly decreased from 10 d ( P<0.05) until more than 21 d after surgery in spinal nerve ligation group compared with na ve group.GDF10 in L5 spinal cord detected at 10 d after surgery by Western blot was significantly down-regulated in spinal nerve ligation group compared with na ve group (P<0.05).CONCLUSION:Spinal nerve ligation induces the decrease in GDF 10 expression in spinal dorsal horn .The down-regulation of GDF10 may contribute to the regulation of hyperpathia caused by mechanical stimulation after the injury of spinal nerve .

Objective To explore the learning and memory impairment and pathology in hippocampus in rats after spinal cord contu-sion. 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 wa-ter 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 sig-nificantly 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 abnor-mal 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 hippo-campus.