8周耐力训练对Nrf2敲除鼠骨骼肌肌浆网钙调控的影响

The Effects of Endurance Training on the Regulation of Sarcoplasmic Reticulum Calcium in Nrf2 Knockout Mice

目的:研究8周耐力训练对Nrf2敲除鼠骨骼肌肌浆网Ca^(2+)调节的作用及机制。方法:8周龄Nrf2敲除鼠和野生鼠各20只,分别随机分为安静组和运动训练组,即野生安静组(WC)、野生运动组(WE)、敲除安静组(KC)和敲除运动组(KE)。运动组动物适应性训练1周后在标准小动物跑台上进行跑台运动。运动方案:坡度0°,12m/min,60min/天,5天/周,共持续8周。在最后一次运动48h后,所有小鼠脱颈椎处死,取两侧腿部骨骼肌。采用甲基百里香酚蓝比色法测定骨骼肌中Ca^(2+)浓度,Western Blot方法测定骨骼肌总蛋白兰尼定受体(RyR)、FK506结合蛋白(FKBP12)、钙调蛋白(CaM)和肌浆网Ca^(2+)-ATP酶(SERCA)的表达。结果:1)KC组RyR、FKBP12、CaM蛋白表达显著高于WC组(P<0.05);KE组CaM蛋白表达显著低于KC组(P<0.05);2)KC组SERCA1蛋白表达显著低于WC组(P<0.05),KE组SERCA1蛋白表达显著高于KC组(P<0.05);3)Nrf2敲除鼠骨骼肌组织中Ca^(2+)浓度与野生鼠无差异,8周耐力训练后也无显著性变化。结论:1)Nrf2敲除鼠骨骼肌钙释放通道RyR和钙调蛋白CaM表达呈现代偿性增加。骨骼肌SERCA1蛋白表达减少,钙回收功能下降;2)8周耐力训练增强了骨骼肌钙释放功能,对于野生鼠增加了钙释放通道RyR的表达,而对于Nrf2敲除鼠CaM对RyR功能的抑制作用减弱。另外,8周耐力训练可以改善Nrf2缺失引起的钙回收功能下降。

Objective：To investigate the effects of eight weeks endurance training on the regulation of sareoplasmie reticulum calcium in Nrf2 knockout mice. Methods： Eight weeks Nrf2 knock out （KO）mice and wild mice were randomly assigned to a sedentary control group and an exercise training group （n=10）. wild control group （WC）, wild exercise group （WE）, KO control group （KC）and KO exereise group （KE）. Mice in exercise groups underwent 60min/ day treadmill running at speed of 12m/min for eight weeks. Skeletal muscle was collected 48 hours after training. The concentration of Ca^2＋ （[Ca^2＋ ]）was tested by MTB. The protein expressions of Nrf2, RyR, FKBP12, CaM and SERCA in skeletal muscle were analyzed by Western Blot. Results： 1）Campared with WC, the expression of RyR, FKBP12 and CaM in KC were significantly increased （P〈0.05） ; while after eight weeks training decreased the expression of CaM in KE than KC（P〈0. 05）; 2） SERCA1 in KC was decreased than WC （P〈0. 05）, while SERCA1 was increased in KE than KC; 3） There is no difference of [ Ca^2＋]among groups. Conclusion： 1）The expression of RyR and CaM were compensatory increased in Nrf2 KO mice; The expression of SERCA1 was decreased in Nrf2 KO mice, inducing the capacity of recruiting Ca^2＋ in sarcoplasmic reticulum was decreased; 2 ） Eight weeks endurance training increased the capacity of sarcoplasmie retieulum Ca^2＋ release by increasing the expression of RyR in wild mice, while by weakening the inhibition of CaM in Nrf2 KO mice. Eight weeks endurance training can repair the decline of the capacity of recruiting Ca^2＋ in Nrf2 KO mice sarcoplasmic reticulum.