利多卡因与神经生长因子预处理对沙土鼠脑缺血／再灌注损伤的保护作用

A study of the protective effects of lidocaine and nerve growth factor pretreatment on cerebral isehemia/ reperfusion injury in gerbils

目的探讨利多卡因与神经生长因子（NGF）预处理对脑缺血／再灌注（I／R）损伤神经细胞凋亡的影响。方法将54只蒙古种沙土鼠按随机数字表法分为正常对照组（A组）、利多卡因对照组（L组）、NGF对照组（N组）、利多卡因预处理12、24、48h组（L12、L24、L48组）和NGF预处理12、24、48h组（N12、N24、N48组）9组，每组6只。除A组外，各组均夹闭双侧颈总动脉20min后再松夹，造成I／R损伤模型。采用原位末端缺刻标记法（TUNEL）检测海马CA1区神经细胞凋亡数，采用免疫组化法检测海马CA1区Bcl-2、Bax表达的阳性细胞数。结果利多卡因与NGF不同时间预处理组CA1区神经细胞凋亡数（个：L12组32．87±0．99，L24组31．90±4．14，L48组24．50±0．70；N12组32．80±1．27，N24组32．83±1．30，N48组23．30±0．86）和Bax阳性细胞数（个：L12组33．47±1．21，L24组33．70±1．20，L48组24．67±2．09；N12组32．17±2．2l，N24组31．97±1.79，N48h组23．27±1．20）均较相应对照组[细胞凋亡数（个）：L组67．43±3．92，N组67．80±3．82；Bax阳性细胞数（个）：L组59．73±1．32，N组59．37±1．543显著减少，而Bcl-2阳性细胞数（个：L12组36．60±3．31，L24组34．73土1．82，L48组65．17士1．53；N12组35．70士1．18，N24组37．30±3．86，N48组62．77±2．91）则较相应对照组（个：L组24．53±1．48，N组25．43±1．85）显著增加（P〈0．05或P〈0．01）；其中48h组较12h组和24h组作用更显著；而两个预处理组间不同时间凋亡细胞、Bcl－2、Bax的表达比较差异均无统计学意义。结论利多卡因与NGF预处理均可减轻脑I／R损伤引起的神经细胞凋亡，具有脑保护作用，以缺血前48h预处理效果明显，机制可能与Bcl－2及Bax表达有关。

Objective To study the protective effects of lidocaine and nerve growth factor （NGF） pretreatment on cerebral ischemia/reperfusion （I/R） injury. Methods Fifty-four Mongolian gerbils were randomly divided into nine groups： normal group （Group A）, lidocaine control group （Group L）, NGF control group （Group N）, lidocaine pretreatment groups at the point of 12, 24, 48 hours （named respectively Group L12, L24, L48）, NGF pretreatment groups with NGF given 12, 24, 48 hours before injury （named respectively Group N12, N24, N48）, with 6 animals in each group. Except Group A, the carotid artery on both sides were occluded for 20 minutes, then they were released to allow reperfusion. Alteration of apoptosis was observed with terminal-deoxynucleotidyl transferase mediated dUTP nick end labeling （TUNEL） and the expression of Bcl-2 and Bax was assessed by immunohistochemistry method. Results No apoptosis, Bcl-2 and Bax were found in Group A. In lidocaine or NGF pretreatment group, the expression of Bcl-2 （Group L12：36.60 ± 3.31, Group L24：34.73 ± 1.82, Group L48：65.17 ± 1.53; Group N12： 35.70±1.18, Group N24： 37. 30±3.86, Group N48： 62. 77±2. 91） was obviously increased comparing with control group （Group L： 24.53± 1.48, Group N： 25.43± 1.85）, but the number of the apoptosis （Group L12： 32.87±0.99, Group L24： 31.90±4.14, Group L48.. 24.50±0.70; Group N12： 32.80±1.27, Group N24.. 32.83±1.30, Group N48： 23.30±0.86） and Bax expression （Group L12： 33.47＋1.21, Group L24： 33.70±1.20, Group L48： 24. 67±2.09; Group N12： 32.17±2.21, Group N24： 31.97±1.79, Group N48： 23.27±1.20） were significantly decreased comparing with the control group （the number of the apoptosis： Group L 67.43±3.92, Group N 67.80±3.82; Bax： Group L 59.73±1.32, Group N 59. 37±1.54, P〈 0. 05 or P〈0. 01）. In lidocaine and NGF pretreatment groups, the number of cell apoptosis and expression Bax were significantly lower at 48 hours than those at 12 hours or 24 hours, but the cell expression Bcl-2 was obviously higher （all P〈0. 05）. However, there was no difference between lidocaine and NEG pretreatment groups at each time point in regard of the number of cell apoptosis, expression of Bel-2 and Bax. Conclusion Lidocaine and NGF pretreatment before cerebral I/R can alleviate I/R injury to the cerebral tissue. The protective effect was most obvious when the treatment was given 48 hours before ischemia. The mechanism may be related with an increase in expression of Bcl-2 as well as a decrease in Bax level.