大鼠坐骨神经缩窄损伤致机械痛敏和热痛敏的性别差异

Gender differences in mechanical and thermal hyperalgesia induced by chronic constriction injury of sciatic nerve in rats

目的观察并测定雌雄性慢性坐骨神经缩窄损伤(CCI)模型大鼠的机械痛阈、热痛阈、皮肤温度及皮肤厚度等指标,研究CCI大鼠的行为学性别差异。方法健康清洁级SD大鼠,分为雌性组(F组)、雄性组(M组),每组20只。通过坐骨神经结扎复制经典的CCI大鼠神经病理性疼痛模型,记录各组实验动物行为学指标:即机械缩足反射阈值、热缩足反射持续时间、右后足皮肤温度及皮肤厚度在各个时间点(手术前1d及术后1,3,7,14d)的变化情况。结果各组大鼠坐骨神经结扎后,均出现了CCI模型明显的热痛敏(F 5.29±1.01,M 8.61±0.92,P<0.05)和机械痛敏(F 1.68±0.67,M 4.80±2.19,P<0.05)反应,雌性组痛阈均较雄性组明显降低;且雌性组与雄性组皮肤厚度(F 3.69±0.17,M 3.93±0.20)及皮肤温度(F 25.72±0.45,M 25.53±0.45)差异无统计学意义(P>0.05);雌性CCI大鼠发生痛敏发生及皮温升高厚度增加明显早于雄性CCI大鼠(雌鼠术后1d,雄鼠术后3d)。结论 CCI大鼠行为学存在显著性别差异,表现在热痛、机械痛等方面。

Objective To measure the mechanical pain threshold,thermal pain threshold,skin temperature and skin thickness in male and female CCI(chronic constriction injury of sciatic nerve,CCI)model rats,and to study the behavioral gender differences of CCI rats.Methods Forty SD rats were used in this study,half female and half male.Classical CCI rat neuropathic pain models were replicated by a sciatic nerve ligation.The behavioral parameters of each experimental animal were recorded in detail,namely mechanical retraction reflex threshold,thermal withdrawal duration,right hind paw skin temperature,and skin thickness changed at various time points(1 day before surgery and 1,3,7,14 days after surgery).Results After a sciatic nerve ligation to rats,the CCI model rats showed more pronounced thermal(F 5.29±1.02,M 8.61±0.92,P<0.05)and mechanical(F 1.68±0.67,M 4.80±2.19,P<0.05)hypersensitivity reactions.The mechanical and thermal pain thresholds of the female group were significantly lower than those of the male group.And the skin thickness(F 3.69±0.17,M 3.93±0.20)and skin temperature(F 25.72±0.45,M 25.53±0.45)of female group and male group showed no significant difference(P>0.05).Female CCI rats developed hyperalgesia earlier than male ones and increased thickness of skin temperature arisen also occurred earlier than them(1 day after surgery in female rats and 3 days after surgery in male rats).Conclusion There is a behavioral gender difference in the thermal and mechanical pain thresholds of CCI rats.