中枢乳酸干预在运动疲劳介导苍白球神经元电活动变化中的作用

Role of Lactate Intervention in Exercise Fatigue-induced Electrical Activity Changes of Gpi Neurons in Rats

通过人工干预脑内乳酸浓度,观察能量代谢对大鼠苍白球内侧部(globus pallidus internal segment,GPi)神经元电活动的影响,从脑能量代谢角度揭示GPi神经元在运动性中枢疲劳中的可能作用机制。方法:Wistar大鼠随机分为安静对照组(CG)、乳酸干预组(10 mmol/L组、100 mmol/L组)。采用玻璃微电极记录到GPi神经元稳定电信号后,于侧脑室微量注射乳酸阻断剂(alpha-cyano-4-hydroxycinnamate,4-CIN),观察记录到神经元电活动变化情况,对其进行统计分析。结果:与CG组相比,4-CIN1和4-CIN2组神经元放电频率均明显降低(P<0.01),4-CIN2组神经元放电频率较4-CIN1组明显降低(P<0.05);与CG组相比,4-CIN1规则放电比例显著降低(P<0.05),不规则放电和爆发式放电比例显著升高(P<0.05),4-CIN2组规则放电数目较4-CIN1组显著降低(P<0.01),不规则放电和爆发式放电均显著升高(P<0.01)。结论:4-CIN影响神经元与星形胶质细胞之间的乳酸转运过程引起GPi内乳酸转运障碍,抑制GPi神经元放电活动,且抑制作用存在剂量依赖;由此推测,阻断神经元对乳酸的摄取与利用可能是导致神经元电活动变化的原因之一。

Objective:Based on brain energy metabolism,we investigated effects of lactate intervention on spontaneous firing of GPi in rats to reveal the possible mechanism of neuronal electrical activity in exercise-induced fatigue.Methods:Male Wistar rats were randomly divided into control group(CG),lactate intervention group(4-CIN) respectively for 10 mmol/L group and 100 mmol/L group.We used the extracellular glass microelectrode technique to record the stable neural firing signal,then observe effect of intracerebroventricular injections of brain lactate blockers(4-CIN) on neural firing.Results:Compared with the control group,the neural firing rates in 4-CIN1 and 4-CIN2 significantly reduced and 4-CIN2 was lower than4-CIN1(P<0.01).The percentage of regular firing pattern neurons in 4-CIN1 reduced compared with control group(P<0.05),while the irregular firing pattern and burst neurons increased(P<0.05); the percentage of regular firing pattern neurons in 4-CIN2 were markedly lower than 4-CIN1(P<0.01),while the irregular firing pattern and burst neurons were observably higher(P<0.01).Conclusion:The dysfunction of lactate transport caused by the blocking of lactate conduction between neurons and astrocytes could inhibit the spontaneous firing of GPi's neurons,and the inhibition effects depended on the dose of 4-CIN.It is supposed that one of the possible mechanism of changes in neural firing activity was the block of lactate uptake and utilization in neurons.