Background Intense exercise can cause injury and apoptosis, but few studies have reported its effect on the central nervous system （CNS）. The initial reason for hippocampus injury is the excitotoxicity of glutamate and calcium overload. Intracellular free Ca2＋ （[Ca2＋]i） overload may trigger the apoptosis pathway and neuron damage. The aim of this study was to investigate whether intense exercise could cause hippocampus apoptosis and neuron damage and then to determine which pathway was activated by this apoptosis. Methods We used one bout of swimming exhaustion rats as models. Intracellular [Ca2~]i was measured to estimate the calcium overload by Fura-2/AM immediately after exhaustion; glial fibrillary acidic protein （GFAP） and synaptophysin （SYP） immunofluorescence were performed for estimating astrocyte activation and synapse plasticity 24 hours after exhaustion. Apoptosis cells were displayed using dUTP nick end labelling （TUNEL） stain; endoplasmic reticulum （ER） stress-induced apoptosis pathway and mitochondrial apoptosis pathway were synchronously detected by Western blotting. Results An increasing level of intracellular [Ca2＋]i （P 〈0.01） was found in the hippocampus immediately after exhaustion. GFAP and SYP immunofluorescence showed that the astrocytes are activated, and the synapse plasticity collapsed significantly 24 hours after exhaustion. TUNEL stain showed that the number of apoptosis cells were notably raised （P 〈0.01）; Western blotting of the apoptosis pathway showed increasing levels of caspase-3 cleavage （P 〈0.01）, Bax （P 〈0.01）, caspase-12 cleavage （P 〈0.01）, C/EBP-homologous protein （CHOP） （P 〈0.01）, and phospho-Junamino- terminal kinases （p-JNK; P 〈0.01） and decreasing level of Bcl-2 （P 〈0.01）. Our results proved that exhaustion can induce hippocampus injury and apoptosis by [Ca2＋]i overload, with collapsed synaptic plasticity as the injury pattern and ER stress-induced apoptosis as the activated pathway. Concl
目的:观察一次性力竭运动对小鼠肝脏和骨骼肌组织内质网应激的影响。方法:16只雄性C57/BL6小鼠随机分为安静组和运动组,每组8只。运动组进行一次性力竭游泳,4小时后取材;安静组不运动,取材时间和方法同运动组。测定肝脏和股四头肌内质网应激蛋白葡萄糖调节蛋白78(glucose-regulated protein 78,GRP78)、磷酸化和非磷酸化的双链RNA依赖的蛋白激酶样内质网类激酶[double-stranded RNA-dependent protein kinase(PKR)-like ER kinase,PERK]、磷酸化和非磷酸化的肌醇需酶1(inositol requiring enzyme 1,IRE1)的蛋白表达量及GRP78、剪切型的X盒结合蛋白1(X box binding protein 1 splicing,XBP1s)、C/EBP同源蛋白(C/EBP homologous protein,CHOP)、生长停滞和诱导DNA损伤基因34(growth arrest and DNA damage-inducible gene 34,GADD34)mR-NA的表达量,测定血糖、肝糖原和肌糖原水平,光镜下对肝脏和骨骼肌组织进行形态学观察。结果:与安静组相比,运动组肝脏和股四头肌内质网应激标志性蛋白GRP78、p-PERK/PERK、p-IRE1/IRE1及GRP78、XBP1s、CHOP、GADD34的mRNA表达均显著增加(P<0.01),血糖、肝糖原和肌糖原均显著下降(P<0.05)。运动组糖原含量与内质网应激标志物表达量呈负相关(P<0.01),部分肝细胞胞浆水肿。结论:一次性力竭性游泳可引起内质网应激增强。肝糖原和肌糖原的储备和消耗可能与内质网的应激程度有关。
