RESUMO
Objective To examine role and possible mechanism of enriched environment (EE) on regulating recovery of visual function in adult monocular deprivation amblyopia mice.Methods A total of 72 healthyKunming mice were divided into normal control group,monocular deprivation (MD) group,MD+EE group and M D+ fluoxetine group by random number table.Except for the normal control group,the mice in the other groups were sutured on the right eyelid 21 days after birth to establish MD amblyopia model.the mice were fed in standard environment or EE for 4 weeks according to the group.Visual acuity and flash visual evoked potential (F-VEP) of mice in each group were detected.The distribution of microtubule associated protein 2 (MAP2) in visual cortex of adult amblyopic mice were detected by immunohistochemistry.The expression of MAP2,synaptophysin (SYP) and postsynaptic density protein-95 (PSD-95) protein in visual cortex of adult amblyopic mice were detected by western blot.The experimental protocol was approved by the Animal Care and Use Committee of Hunan Children's Hospital and conformed to the National Institutes of Health Guide for the Care and Use of Laboratory Animals.Results There was a significant difference in the visual acuity of deprived eye among each group (F=114.632,P＜0.001).The visual acuity in MD group is lower than that in normal control group,with a significant difference (t =15.480,P＜0.001).Compared with MD group,visual acuity was restored in MD+ EE group and MD +fluoxetine group,with significant differences (t =15.071,P ＜ 0.001;t =14.841,P ＜ 0.001).There was a significant difference in the P2 latency and amplitude of F-VEP in deprived eye among each group (F=36.510,P=0.000;F=34.140,P=0.000).Compare with normal control group,P2 latency was prolonged and P2 amplitude of F-VEP was decreased in deprived eye in MD group,with significant differences (t =10.220,P =0.000;t =10.09,P =0.000).Western blot assay showed that there was a significant difference in the expression of MAP2 in visual cortex contralateral deprived eye among each group (F=18.142,P=0.000).The expression of MAP2 in MD group was significantly lower than that in normal contral group (t=3.056,P＜0.01);Compared with MD group,MAP2 expression was increased in MD+EE group and MD+fluoxetine group (t =2.541,P =0.031;t =2.157,P =0.017).There were significant differences in the expression of SYP and PSD-95 in visual cortex contralateral to deprived eye among each group (F =12.871,P =0.000;F =25.060,P =0.000).Compared with normal contral group,SYP and PSD-95 expression in visual cortex were down-regulated in MD group,with significant differences (t =6.054,P =0.000;t =8.631,P =0.000).The expression of SYP and PSD-95 protein in MD+EE group and MD+fluoxetine group were significantly higher than those in MD group (all at P＜0.05).Conclusions EE can recover visual function through up-regulating the expression of MAP2,which can modulate the dendritic branch trim and neural plasticity of visual cortex in adult MD mice.
RESUMO
Objective This study was to investigate the effect of caloric restriction on the plasticity of visual cortex in adult monocular deprivation (MD) amblyopic mice,as well as to promote the treatment of amblyopia,and to explore the possible molecular mechanism of this benefical effect.Methods Fifty healthy newborn Kunming mice of clean grade were randomly divided into 3 groups using a random number table method:normal control group (n =14),MD+ ad libitum group (n=18) and MD+ caloric restriction group (n=18).A mouse model of adult MD amblyopia was established,and caloric restriction intervention and ad libitum were performed on MD + caloric restriction group and MD+ ad libitum group,respectively.The visual acuity and flash visual evoked potential (F-VEP) of each group were detected.The synaptic structure of visual cortex neurons was observed by transmission electron microscope,and the expression of phosphorylated AMP-activated protein kinase-α(p-AMPKα) and silent information regulator 1 (SIRT1) in visual cortex were detected by Western blot.The animal feeding and use was in accordance with the standards set by the ARVO.Results The weight of mice in MD+ caloric restriction group increased from the beginning of the first week,and was significantly lower than that in the MD + ad libitum group (P＜0.05).Compared with the MD+ ad libitum group,the visual acuity was restored,the latency was shortened,and the amplitude of F-VEP was increased in the deprived eyes of MD+ caloric restriction group (all at P＜0.05).Transmission electron microscope observation showed that the width of synaptic gap of visual cortical neurons was significantly narrower,and the thickness of postsynaptic density was significantly thicker in MD+ caloric restriction group than that in the MD+ ad libitum group (both at P＜0.05);compared with the normal control group,the synaptic gap was widened and the postsynaptic density was significantly thicker than that in the MD+ ad libitum group (both at P＜0.05).Western blot showed that the expression of p-AMPKα in visual cortex in the normal control group,MD+ caloric restriction group and MD+ ad libitum group was 0.89±0.03,0.94±0.02 and 0.74 ±0.02,and the expression of SIRT1 was 0.97±0.11,0.95±0.14 and 0.58±0.13,respectively,showing significant differences among the three groups (F =14.57,P =0.00;F=23.91,P=0.00),the expressions of p-AMPKα and SIRT1 in visual cortex were increased in MD+ caloric restriction group than those in M D+ ad libitum group (both at P＜0.05).Conclusions Caloric restriction can restore the ultrastructure of synapses and improve the visual cortical plasticity in adult MD mice,so that help to improve visual function.Its mechanism may be related to the activation of AMPK-SIRT1 pathway.