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 ...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. Conclusion Intense exercise can cause excessive apoptosis and synapse plasticity damage in the hippocampus with [Ca2＋]i overload as the initial reason, and thus provides leads for therapeutic interventions in the brain health of athletes.展开更多
Background： Our previous study has confirmed that one bout of exhaustion （Ex） can cause hippocampus neurocyte damage, excessive apoptosis, and dysfunction, its initial reason is intracellular calcium overload in hi...Background： Our previous study has confirmed that one bout of exhaustion （Ex） can cause hippocampus neurocyte damage, excessive apoptosis, and dysfunction, its initial reason is intracellular calcium overload in hippocampus triggered by N-methyl-D-aspartic acid receptor （NMDAR） over-activation. NMDAR activation can be suppressed by y-aminobutyric acid （A） receptor （GABAAR）. Whether GABAAR can prevent intense exercise-induced hippocampus apoptosis, damage, or dysfunction will be studied in this study. Methods： According to dose test, rats were randomly divided into control （Con）, Ex, muscimol （MUS, 0.1 mg/kg） and bicuculline （BIC, 0.5 mg/kg） groups, then all rats underwent once swimming Ex except ones in Con group only underwent training, lntracellular free calcium concentration （[Ca2＋]i） was measured by Fura-2-acetoxymethyl ester; glial fibrillary acidic protein （GFAP） and synaptophysin （SYP） immunofluorescence were also performed; apoptosis were displayed by dUTP nick end labeling （TUNEL） stain; endoplasmic reticulum stress-induced apoptosis pathway was detected by Western blotting analysis; Morris water maze was used to detect learning ability and spatial memory. Results： The appropriate dose was 0.1 mg/kg for MUS and 0.5 mg/kg for BIC. Ex group showed significantly increased [Ca^2＋]i and astrogliosis; TUNEL positive cells and levels of GFAP, B cell lymphoma-2 （Bcl-2） associated X protein （Bax）, caspase-3, caspase-12 cleavage, CCAAT/enhancer binding protein homologous protein （CHOP）, and p-Jun amino-terminal kinase （p-JNK） in Ex group also raised significantly compared to Con group, while SYP, synapse plasticity, and Bcl-2 levels in Ex group were significantly lower than those in Con group. These indexes were back to normal in MUS group. BIC group had the highest levels of [Ca^2＋]i, astrogliosis, TUNEL positive cell, GFAP, Bax, caspase-3, caspase-12 cleavage, CHOP, and p-JNK, it also gained the lowest SYP, synapse plasticity, and Bcl-2 levels among all groups. Water maze test showed that Ex group had longer escape latency （EL） and less quadrant dwell time than Con group; all indexes between MUS and Con groups had no significant differences; BIC had the longest EL and least quadrant dwell time among all groups. Conclusions： Activation of GABAAR could prevent intense exercise-induced synapses damage, excessive apoptosis, and dysfunction of hippocampus.展开更多
基金This study was supported by grants from the National Natural Science Foundation of China （No. 30270636 and No. 30671015）.
文摘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. Conclusion Intense exercise can cause excessive apoptosis and synapse plasticity damage in the hippocampus with [Ca2＋]i overload as the initial reason, and thus provides leads for therapeutic interventions in the brain health of athletes.
基金This research was supported by grants from the National Nature Science Foundation of China
文摘Background： Our previous study has confirmed that one bout of exhaustion （Ex） can cause hippocampus neurocyte damage, excessive apoptosis, and dysfunction, its initial reason is intracellular calcium overload in hippocampus triggered by N-methyl-D-aspartic acid receptor （NMDAR） over-activation. NMDAR activation can be suppressed by y-aminobutyric acid （A） receptor （GABAAR）. Whether GABAAR can prevent intense exercise-induced hippocampus apoptosis, damage, or dysfunction will be studied in this study. Methods： According to dose test, rats were randomly divided into control （Con）, Ex, muscimol （MUS, 0.1 mg/kg） and bicuculline （BIC, 0.5 mg/kg） groups, then all rats underwent once swimming Ex except ones in Con group only underwent training, lntracellular free calcium concentration （[Ca2＋]i） was measured by Fura-2-acetoxymethyl ester; glial fibrillary acidic protein （GFAP） and synaptophysin （SYP） immunofluorescence were also performed; apoptosis were displayed by dUTP nick end labeling （TUNEL） stain; endoplasmic reticulum stress-induced apoptosis pathway was detected by Western blotting analysis; Morris water maze was used to detect learning ability and spatial memory. Results： The appropriate dose was 0.1 mg/kg for MUS and 0.5 mg/kg for BIC. Ex group showed significantly increased [Ca^2＋]i and astrogliosis; TUNEL positive cells and levels of GFAP, B cell lymphoma-2 （Bcl-2） associated X protein （Bax）, caspase-3, caspase-12 cleavage, CCAAT/enhancer binding protein homologous protein （CHOP）, and p-Jun amino-terminal kinase （p-JNK） in Ex group also raised significantly compared to Con group, while SYP, synapse plasticity, and Bcl-2 levels in Ex group were significantly lower than those in Con group. These indexes were back to normal in MUS group. BIC group had the highest levels of [Ca^2＋]i, astrogliosis, TUNEL positive cell, GFAP, Bax, caspase-3, caspase-12 cleavage, CHOP, and p-JNK, it also gained the lowest SYP, synapse plasticity, and Bcl-2 levels among all groups. Water maze test showed that Ex group had longer escape latency （EL） and less quadrant dwell time than Con group; all indexes between MUS and Con groups had no significant differences; BIC had the longest EL and least quadrant dwell time among all groups. Conclusions： Activation of GABAAR could prevent intense exercise-induced synapses damage, excessive apoptosis, and dysfunction of hippocampus.
