Sex influences on sensory responses followingspinothalamic tract injury in rats

Introduction: There is some evidence of significant differences in the recovery after spinal cord injury (SCI) between males and females. In this study, we investigated the sensory function and involvement of astrocytes in the sex differences of central pain syndrome in the unilateral spinothalamic tract (STT) injury model in rats. Methods: Rats were divided into two groups: SCI and Sham groups received a unilateral electrolytic lesion on STT at T8-T9 and a control sham surgery respectively. After recovery from surgery, the sensory function was monitored for 28 days using tail flick and von Frey filament tests. The glial fibrillary acidic protein (GFAP) level was also measured by Western blot at the same time points. Results: Mechanical hypersensitivity was increased from days 3 to 28 post-injury in male rats (P 0.001), but no significant change was observed in females. In the tail flick model, male rats had significantly elevated thermal withdrawal latency on day3 after STT lesion, while females showed a reduction in latency (P 0.001). Sex differences in GFAP level were observed during 4 weeks of study after injury. Results in the first week showed that GFAP level decreased in females, but the marked elevation was observed from days 7 to 28 in males (P 0.05). Conclusion: This study revealed the sex differences in sensory dysfunction and the related astrocyte reactivity after SCI. It suggests a need for more studies using both sexes to fully explore the influence of sex on the recovery of sensory impairments post-SCI.