基于Nrf2-ARE信号通路探析己酮可可碱对癫痫大鼠脑内氧化应激的影响

Analysis of the effect of pentoxifylline on oxidative stress in brains of epileptic rats based on Nrf2-ARE signaling pathway

目的基于核因子E2相关因子2(Nrf2)-抗氧化反应元件(ARE)信号通路探析己酮可可碱(PTX)对癫痫(EP)大鼠脑内氧化应激的影响。方法实验纳入36只健康、成年雄性Wistar大鼠,并按照完全随机法分为空白对照组(腹腔注射等渗盐水)、EP对照组(诱发EP发作)、PTX组(诱发EP发作+PTX预处理),每组12只。观察各组大鼠行为学改变,记录EP发作率、发作潜伏期,断头处死取黑质、海马组织后检测氧化应激指标及Nrf2-ARE信号通路相关蛋白表达水平。结果给药后空白对照组大鼠未见异常反应,PTX组EP发作率(33.3%)、发作等级[(2.14±0.40)vs(3.09±0.58)]均明显低于EP对照组,且发作潜伏期明显延长(P<0.05)。与空白对照组相比,EP对照组大鼠黑质、海马组织丙二醛(MDA)含量明显高,谷胱甘肽(GSH)、超氧化物岐化酶(SOD)活性显著降低(P<0.05);而相比EP对照组,PTX组黑质、海马组织MDA含量[(760.22±74.86)nmol/g vs(682.93±69.01)nmol/g·pro、(842.24±101.17)nmol/g·pro vs(705.46±80.87)nmol/g·pro]明显降低,GSH[(68.31±12.57)μg/g·pro vs(94.43±14.11)μg/g·pro、(64.27±10.28)μg/g·pro vs(87.36±11.11)μg/g·pro]、SOD[(95.34±8.72)U/mg·pro vs(120.60±10.04)U/mg·pro,(91.33±8.46)U/mg·pro vs(118.46±9.94)U/mg·pro]活性明显增加(P<0.05)。与空白对照组相比,EP对照组大鼠黑质组织、海马Nrf2、HO-1蛋白表达明显降低(P<0.05);而PTX组黑质组织、海马Nrf2相比EP对照组,显著增加[(0.72±0.09)vs(0.30±0.04)、(0.34±0.06)vs(0.21±0.03)]、HO-1[(0.66±0.08)vs(0.34±0.05)、(0.48±0.08)vs(0.31±0.05)],NQO-1蛋白表达显著增加[(0.48±0.07)vs(0.25±0.06)、(0.78±0.11)vs(0.68±0.07),P<0.05],且海马组织表达恢复至空白对照组水平(P>0.05),黑质组织表达明显高于空白对照组水平(P<0.05)。结论 PTX可抑制EP发作,改善EP发作早期大鼠脑内氧化应激状态,可能机制为PTX可特异性激活Nrf2-ARE信号通路。

Objective To investigate the effects of pentoxifylline(PTX) on oxidative stress in brains of epileptic(EP) rats based on the nuclear factor E2 related factor 2(Nrf2) antioxidant response element(ARE) signal pathway. Methods Thirty-six healthy and adult male Wistar rats were included in the experiment and were divided into blank control group(peritoneal injection of isotonic saline), EP control group(induced EP episode), and PTX group(induced EP episode + PTX pretreatment) according to a completely random method, then 12 rats in each group. The behavioral changes of rats in each group were monitored, and the EP attack rate and seizure latency were recorded. The rats were sacrificed to collect substantia nigra and hippocampus for testing oxidative stress indicators and expression levels of Nrf2 ARE signaling pathway-related proteins. Results No abnormal reaction was observed in the control group after treatment. The EP attack rate in the EP control group reached 83.33%. The EP attack rate(33.3%) and the attack level((2.14±0.40) vs(3.09±0.58)) in the PTX group were significantly lower than those in the EP control group, and the seizure latency was significantly longer than that in the EP control group(P<0.05). Compared with the blank control group, the rats in the EP control group had significantly higher levels of malondialdehyde(MDA) in the substantia nigra and hippocampus, and significantly reduced glutathione(GSH) and superoxide dismutase(SOD) activities(P<0.05). Compared with EP control group, MDA content in substantia nigra and hippocampus of PTX group((760.22±74.86) nmol/g vs(682.93±69.01) nmol/g·pro,(842.24±101.17) nmol/g·pro vs(705.46±80.87) nmol/g·pro) were significantly reduced, GSH((68.31±12.57) μg/g·pro vs(94.43±14.11) μg/g·pro,(64.27±10.28) μg/g·pro vs(87.36±11.11) μg/g·pro), SOD((95.34±8.72) U/mg·pro vs(120.60±10.04) )U/mg·pro,(91.33±8.46) U/mg·pro vs(118.46±9.94) U/mg·pro) activity was significantly increased(P<0.05). Compared with the blank control group, the expressions of substantia nigra tissue, hippocampal Nrf2, and HO1 protein in the EP control group rats were significantly reduced(P<0.05);while the substantia nigra tissue and hippocampal Nrf2 protein in the PTX group were significantly increased compared with the EP control group((0.72±0.09) vs(0.30±0.04),(0.34±0.06) vs(0.21±0.03)), HO 1((0.66±0.08) vs(0.34±0.05),(0.48±0.08) vs(0.31±0.05)), NQO1 protein expression was significantly increased((0.48±0.07) vs(0.25±0.06),(0.78±0.11) vs(0.68±0.07), P<0.05), and the expression of hippocampal tissue returned to the blank control group(P>0.05)). The expression of substantia nigra tissue was significantly higher than that of the blank control group(P<0.05). Conclusion PTX can inhibit EP seizure and improve the oxidative stress in the brain of rats at the early stage of EP. The possible mechanism is that PTX can specifically activate Nrf2 ARE signaling pathway.