鞘内注射右美托咪定对幻肢痛大鼠行为及脊髓胶质细胞的影响

Effects of dexmedetomidine intrathecal injection on the behavior and the spinal cord glial cells of rats with phantom limb pain

目的探讨鞘内注射右美托咪定(dexmedetomidine,DEX)对幻肢痛大鼠行为及脊髓胶质细胞的影响。方法采用坐骨神经慢性压迫性损伤法(chronic constriction injury,CCI)制备大鼠幻肢痛模型。将18只大鼠按照电脑随机数字法分为假手术组、生理盐水处理组和DEX处理组,3组大鼠分别于鞘内注射前(T1),注射后30 min(T2)、12 h(T3)、2 d(T4)、1周(T5)进行旷场试验,观察记录大鼠的行为,并检测各时点血液中缓激肽(bradykinin,BK)、组胺(histamine,HIS)含量。1周后通过电脑随机数字法每组选取3只大鼠处死,进行脊髓免疫组化染色,观察各组大鼠脊髓胶质细胞活化水平的改变。结果与假手术组比较,生理盐水处理组和DEX处理组大鼠T1时移动总距离明显减少(P<0.05),移动时间和穿越方格次数减少,但差异无统计学意义;DEX处理组大鼠T2、T3、T4、T5时的移动总距离及移动时间比T1时明显增加(P<0.05),穿越方格次数随时间推移呈增加趋势,但差异无统计学意义。与假手术组比较,生理盐水处理组和DEX处理组大鼠T1时的BK(P>0.05)和HIS(P<0.05)含量呈不同程度增多,DEX处理组大鼠的BK和HIS分别于T3、T2时间点后呈下降趋势,但差异无统计学意义。与假手术组比较,生理盐水处理组大鼠星型胶质细胞和小胶质细胞显著增多(P<0.05);与生理盐水处理组比较,DEX处理组大鼠星型胶质细胞数目显著减少(P<0.05)。结论鞘内注射DEX能够抑制致痛致炎因子产生及胶质细胞活化,从而改善幻肢痛大鼠的行为能力,这为临床幻肢痛治疗提供了新思路。

Objective To investigate the effects of dexmetomide intrathecal injection on the behavior and the spinal cord glial cells of rats with phantom limb pain.Methods Eighteen healthy and clean adult male SD rats were randomly divided into three groups(n=6):sham operation group,control group,and DEX group.The control group and the DEX group were used to establish the model of phantom limb pain by chronic constriction injury of the sciatica(CCI);and the sham operation group was treated with sham operations.One week after the establishment of the model,a single intrathecal injection was carried out.The sham operation group was treated with normal saline,and the control group was treated with DEX at a dose of 30μg/kg.At the time points before the intrathecal injection(T1),and 30 min(T2),12 h(T3),2 d(T4),and 1 week(T5)after the intrathecal injection,the behavior,the bradykinin(BK)and histamine(HIS)contents in the blood of the rats at each time point were observed and recorded.One week later,three rats in each group were randomly selected according to random number table method and killed;and the changes of the glial cell activation in the spinal cords of the rats in each group were observed through immunohistochemical staining.Results Compared with the sham operation group,the total moving distances were significantly reduced in the control group and the DEX group at T1(P<0.05).In the DEX group,the total moving distances of the rats at T2,T3,T4 and T5 were significantly higher than those at T1(P<0.05).The total moving distances and the counts of crossed squares in the DEX group increased with time.The time of movement at T2 and T5 were significantly higher than those of T1(P<0.05).Compared with T1,the BK and HIS values in the control group showed an increasing trend with time;and the BK and HIS values in the DEX group showed a decreasing trend.Compared with the sham operation group,the astrocytes and microglia increased significantly in the control group(P<0.05).Compared with the control group,the count of astrocytes in the DEX group decreased significantly(P<0.05).Conclusion Dexmetomide intrathecal injection can improve the motor behavior of rats with phantom limb pain,inhibit the pain-causing factor and inflammatory factors,and decrease the activation of glial cells in the spinal cord to protect the nerves.Hence it is a new idea for the treatment of phantom limb pain.