不同剂量右美托咪定对创伤性脑损伤大鼠神经炎症反应及神经营养因子的影响

Effects of different concentrations of dexmedetomidine treatment on neuroinflammatory responses and neurotrophic factors after traumatic brain injury in rats

目的探讨不同剂量右美托咪定对创伤性脑损伤(TBI)大鼠神经炎症反应及神经营养因子的影响。方法健康清洁级成年雄性SD大鼠75只,10-12周龄,体重220-250 g。采用随机数字表法将大鼠随机分为五组:假手术组(S组)、TBI组(T组)、右美托咪定25μg/kg组(D25组)、右美托咪定50μg/kg组(D50组)和右美托咪定100μg/kg组(D100组),每组15只。S组仅行头皮切开钻孔手术,T组采用Feeney自由落体法建立TBI模型,D25组、D50组、D100组分别于TBI模型建立后立即腹腔注射右美托咪定25、50、100μg/kg。采用改良神经功能缺损评分(mNSS)评估建模后12、24、48、72 h的神经功能,干/湿比重法检测脑组织含水量,Western blot法检测脑组织肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)及白细胞介素-6(IL-6)蛋白含量,免疫组织化学染色法观察脑组织皮层区脑源性生长因子(BDNF)、神经生长因子(NGF)表达情况。结果与S组比较,T组不同时点mNSS明显升高(P<0.05),脑组织含水量明显增多(P<0.05),脑组织TNF-α、IL-1β、IL-6蛋白含量明显升高(P<0.05),脑组织皮层区BDNF、NGF表达及阳性细胞数明显增多(P<0.05)。与T组比较,D25组、D50组、D100组mNSS明显降低(P<0.05),脑组织含水量明显减少(P<0.05),脑组织TNF-α、IL-1β、IL-6蛋白含量明显降低(P<0.05),脑组织皮层区BDNF、NGF表达及阳性细胞数明显增多(P<0.05)。与D25组比较,D50组不同时点mNSS明显降低(P<0.05),脑组织含水量明显减少(P<0.05),脑组织TNF-α、IL-1β、IL-6蛋白含量明显降低(P<0.05),脑组织皮层区BDNF、NGF表达及阳性细胞数明显增多(P<0.05)。D25组、D100组各指标差异无统计学意义。结论相对于右美托咪定25和100μg/kg,右美托咪定50μg/kg腹腔注射可明显改善脑水肿,减轻神经炎症反应,增加TBI后皮层神经营养因子表达水平,缓解神经功能障碍。

Objective To investigate the effects of different concentrations of dexmedetomidine on neuroinflammatory responses and neurotrophic factors in cerebral cortex of rats after traumatic brain injury(TBI).Methods Seventy-five male SD rats,10-12 weeks,weighing 220-250 g,were randomly divided into 5 groups by using random number table method:sham-operated group(group S),TBI group(group T),dexmedetomidine 25μg/kg group(group D25),dexmedetomidine 50μg/kg group(group D50),and dexmedetomidine 100μg/kg group(group D100),15 rats in each group.Group S only underwent scalp incision and drilling,rat model of TBI was established by Feeney s free fall method.Rats in group D25 were injected intraperitoneally dexmedetomidine 25μg/kg immediately after TBI induction.Rats in group D50 were injected dexmedetomidine 50μg/kg.Rats in group D100 were injected dexmedetomidine 100μg/kg.The neurological dysfunction of rats was evaluated by modified neurological severity scores(mNSS)12,24,48,and 72 hours after modeling.The dry and wet weight method was used to detect the water content of brain tissue.The expression of tumor necrosis factor alpha(TNF-α),interleukin-1β(IL-1β)and IL-6 were determined by Western blot analysis.Immunohistochemical staining was used to observe the expressions of brain-derived growth factor(BDNF)and nerve growth factor(NGF)in cerebral cortex.Results Compared with group S,mNSS score at different time points and brain water content tissue were significantly increased in group T(P<0.05),the expressions of TNF-α,IL-1β,IL-6 and positive cell number of BDNF and NGF in neurons of the cortical area were significantly increased in group T(P<0.05).Compared with the group T,mNSS score at different time points and brain water content were decreased(P<0.05),the expression of TNF-α,IL-1βand IL-6 were significantly decreased(P<0.05),the expression and positive cell number of BDNF and NGF were significantly increased in group D25,group D50 and group D100(P<0.05).Compared with the group D25,mNSS score at different time points and brain water content were significantly decreased(P<0.05),the expression of TNF-α,IL-1βand IL-6 were significantly decreased(P<0.05),and the expression and positive cell number of BDNF and NGF protein were significantly increased in group D50(P<0.05).There were no significantly differences in groups D25 and D100.Conclusion Compared with 25 and 100μg/kg,dexmedetomidine 50μg/kg treatment could reduce brain edema and neuroinflammatory response,enhance the expression level of cortical neurotrophic factor,finally contributing to neurological function recovery after TBI in rats.