AIM:This study aimed to investigate the mechanisms by which treadmill exercise ameliorates de-pressive-like behaviors and hippocampal neuronal damage in chronic restraint stress(CRS)mice by regulating mitophagy via the Sirt1/PGC-1α signaling axis.METHODS:Forty C57BL/6J mice were randomly assigned to control,CRS,CRS+exercise(EXE)and EXE groups(n=10).The mice in CRS and CRS+EXE groups underwent 4 h of daily restraint for 28 consecutive days to establish a depression model.The mice in CRS+EXE and EXE groups received 8 weeks of treadmill training(6 sessions per week).Depressive-like behaviors were evaluated using the open field test,sucrose preference test,and tail suspension test.Hippocampal neuronal morphology and pathological changes were examined using hematoxy-lin-eosin and Nissl staining,while neuronal apoptosis was assessed through TUNEL staining.Mitochondrial ultrastructure was examined via transmission electron microscopy.Mitochondrial membrane potential and ATP content were measured using JC-1 assay and ATP assay kits,respectively.The expression levels of silent information regulator 1(Sirt1),peroxi-some proliferator-activated receptor γ coactivator-1α(PGC-1α),PTEN-induced kinase 1(PINK1)and parkin were as-sessed at both mRNA and protein levels by RT-qPCR and Western blot assays,as well as key markers of mitophagy[mi-crotubule-associated protein 1 light chain 3(LC3)and P62]and apoptosis(cleaved caspase-9 and cleaved caspase-3).RESULTS:Compared with control group,CRS mice exhibited significantly reduced central zone entries and time(P<0.01),decreased sucrose preference(P<0.01),increased immobility time(P<0.01),severe hippocampal neuronal damage,elevated apoptosis rate(P<0.01),mitochondrial deterioration;reduced membrane potential and ATP content(P<0.01),decreased mRNA expressions of Sirt1,PGC-1α,PINK1,and parkin(P<0.01),reduced protein levels of Sirt1,PGC-1α,PINK1,parkin and LC3(P<0.01),and increased expression of P62,cleaved caspase-9,and cleaved caspase-3(P<0.01).The mice in CRS+EXE group showed significant improvements in all these parameters compared to CRS group(P<0.05 or P<0.01).CONCLUSION:Treadmill exercise mitigates CRS-induced depressive-like behaviors,mi-tochondrial dysfunction,and neuronal apoptosis in mice by activating the hippocampal Sirt1/PGC-1α/mitophagy axis.

BACKGROUND:Studies have shown that there is a close relationship between dendritic spine plasticity and Alzheimer's disease,and that resistance or aerobic exercise has some efficacy in improving cognitive dysfunction,but the mechanism of action is unclear.OBJECTIVE:To investigate the effect of aerobic exercise or resistance exercise on dendritic spine plasticity in the hippocampal CA1 region of APP/PS1 transgenic mice.METHODS:Thirty 3-month-old male APP/PS1 mice were selected and randomly divided into three groups:a model group,a resistance exercise group,and an aerobic exercise group.The same litter of 3-month-old C57BL/6J mice were selected as a blank group.Mice in the resistance exercise group were subjected to ladder-climbing exercise and those in the aerobic exercise group were subjected to treadmill exercise for 12 weeks.At the end of the exercise intervention,the water maze experiment and the new arm of the Y maze were used to assess behavioral changes in mice.Hematoxylin-eosin staining,Nissl staining,Golgi staining,and electron microscopy were performed to observe neuronal morphology,Nissl bodies,dendritic spines,and ultrastructural changes in the synapses of the hippocampal region of the mouse brain.The protein expression levels of hippocampal amyloid-beta1-42,Ras,and Drebrin were measured using Western blot analysis.RESULTS AND CONCLUSION:Mice in the model group exhibited a prolonged escape latency over 5 consecutive days(P＜0.05,P＜0.01)and significantly fewer entries into the new arm of the Y maze(P＜0.01).Dendritic spine density in the CA1 region of the hippocampus,as well as Ras and Drebrin expression in the hippocampal tissues of mice in the model group,were lower than those in the normal group(P＜0.01),and amyloid-beta1-42 expression in the hippocampal tissues was higher in the model group compared with the normal group(P＜0.01).Mice in the resistance exercise group and the aerobic exercise group displayed a shortened escape latency over the same 5-day period(P＜0.05,P＜0.01)and showed a significantly greater number of entries into the new arm of the Y maze compared with the normal group(P＜0.01).Dendritic spine density in the CA1 region of the hippocampus,as well as Ras and Drebrin expression in the hippocampal tissues,were higher in both the resistance exercise group and the aerobic exercise group compared with the model group(P＜0.01).Amyloid-beta1-42 expression in the hippocampal tissue was lower in both exercise groups than in the model group(P＜0.01).To conclude,long-term regular aerobic or resistance exercise interventions can increase dendritic spine density and synaptic plasticity in the CA1 region of the hippocampus,enhancing spatial learning and memory abilities in a mouse model of Alzheimer's disease.These effects may be associated with increased expression of Ras and Drebrin proteins in the hippocampus.

AIM:This study aimed to investigate the mechanisms by which treadmill exercise ameliorates de-pressive-like behaviors and hippocampal neuronal damage in chronic restraint stress(CRS)mice by regulating mitophagy via the Sirt1/PGC-1α signaling axis.METHODS:Forty C57BL/6J mice were randomly assigned to control,CRS,CRS+exercise(EXE)and EXE groups(n=10).The mice in CRS and CRS+EXE groups underwent 4 h of daily restraint for 28 consecutive days to establish a depression model.The mice in CRS+EXE and EXE groups received 8 weeks of treadmill training(6 sessions per week).Depressive-like behaviors were evaluated using the open field test,sucrose preference test,and tail suspension test.Hippocampal neuronal morphology and pathological changes were examined using hematoxy-lin-eosin and Nissl staining,while neuronal apoptosis was assessed through TUNEL staining.Mitochondrial ultrastructure was examined via transmission electron microscopy.Mitochondrial membrane potential and ATP content were measured using JC-1 assay and ATP assay kits,respectively.The expression levels of silent information regulator 1(Sirt1),peroxi-some proliferator-activated receptor γ coactivator-1α(PGC-1α),PTEN-induced kinase 1(PINK1)and parkin were as-sessed at both mRNA and protein levels by RT-qPCR and Western blot assays,as well as key markers of mitophagy[mi-crotubule-associated protein 1 light chain 3(LC3)and P62]and apoptosis(cleaved caspase-9 and cleaved caspase-3).RESULTS:Compared with control group,CRS mice exhibited significantly reduced central zone entries and time(P<0.01),decreased sucrose preference(P<0.01),increased immobility time(P<0.01),severe hippocampal neuronal damage,elevated apoptosis rate(P<0.01),mitochondrial deterioration;reduced membrane potential and ATP content(P<0.01),decreased mRNA expressions of Sirt1,PGC-1α,PINK1,and parkin(P<0.01),reduced protein levels of Sirt1,PGC-1α,PINK1,parkin and LC3(P<0.01),and increased expression of P62,cleaved caspase-9,and cleaved caspase-3(P<0.01).The mice in CRS+EXE group showed significant improvements in all these parameters compared to CRS group(P<0.05 or P<0.01).CONCLUSION:Treadmill exercise mitigates CRS-induced depressive-like behaviors,mi-tochondrial dysfunction,and neuronal apoptosis in mice by activating the hippocampal Sirt1/PGC-1α/mitophagy axis.

BACKGROUND:Studies have shown that there is a close relationship between dendritic spine plasticity and Alzheimer's disease,and that resistance or aerobic exercise has some efficacy in improving cognitive dysfunction,but the mechanism of action is unclear.OBJECTIVE:To investigate the effect of aerobic exercise or resistance exercise on dendritic spine plasticity in the hippocampal CA1 region of APP/PS1 transgenic mice.METHODS:Thirty 3-month-old male APP/PS1 mice were selected and randomly divided into three groups:a model group,a resistance exercise group,and an aerobic exercise group.The same litter of 3-month-old C57BL/6J mice were selected as a blank group.Mice in the resistance exercise group were subjected to ladder-climbing exercise and those in the aerobic exercise group were subjected to treadmill exercise for 12 weeks.At the end of the exercise intervention,the water maze experiment and the new arm of the Y maze were used to assess behavioral changes in mice.Hematoxylin-eosin staining,Nissl staining,Golgi staining,and electron microscopy were performed to observe neuronal morphology,Nissl bodies,dendritic spines,and ultrastructural changes in the synapses of the hippocampal region of the mouse brain.The protein expression levels of hippocampal amyloid-beta1-42,Ras,and Drebrin were measured using Western blot analysis.RESULTS AND CONCLUSION:Mice in the model group exhibited a prolonged escape latency over 5 consecutive days(P＜0.05,P＜0.01)and significantly fewer entries into the new arm of the Y maze(P＜0.01).Dendritic spine density in the CA1 region of the hippocampus,as well as Ras and Drebrin expression in the hippocampal tissues of mice in the model group,were lower than those in the normal group(P＜0.01),and amyloid-beta1-42 expression in the hippocampal tissues was higher in the model group compared with the normal group(P＜0.01).Mice in the resistance exercise group and the aerobic exercise group displayed a shortened escape latency over the same 5-day period(P＜0.05,P＜0.01)and showed a significantly greater number of entries into the new arm of the Y maze compared with the normal group(P＜0.01).Dendritic spine density in the CA1 region of the hippocampus,as well as Ras and Drebrin expression in the hippocampal tissues,were higher in both the resistance exercise group and the aerobic exercise group compared with the model group(P＜0.01).Amyloid-beta1-42 expression in the hippocampal tissue was lower in both exercise groups than in the model group(P＜0.01).To conclude,long-term regular aerobic or resistance exercise interventions can increase dendritic spine density and synaptic plasticity in the CA1 region of the hippocampus,enhancing spatial learning and memory abilities in a mouse model of Alzheimer's disease.These effects may be associated with increased expression of Ras and Drebrin proteins in the hippocampus.