热量限制对成年弱视小鼠初级视皮质突触可塑性的调控作用

摘要

目的:探讨热量限制(CR)对成年单眼形觉剥夺(MD)弱视小鼠视皮质突触可塑性的调控作用及可能的分子机制.方法:实验研究.将54只新生健康昆明小鼠按随机数字表法分为正常组、MD+自由进食(AL)组、MD+CR组,每组18只.小鼠21日龄时构建MD模型,35日龄时去除剥夺因素,63日龄时通过行为学检测视敏度及电生理检测视功能;免疫组织化学及Western Blot法检测视皮质组织中可塑性相关蛋白突触后致密蛋白95(PSD95)、突触素(SYP)、生长相关蛋白43(GAP-43)等的表达;RT-PCR检测胰岛素样生长因子1(IGF-1)的表达.采用重复测量双因素方差分析比较各组数据差异.结果:最终正常组、MD+AL组、MD+CR组分别有14、18、18只小鼠完成研究.从第1周开始,MD+CR组小鼠体质量百分比的增加明显低于MD+AL组(P＜0.05).MD+AL组小鼠视敏度明显低于正常组和MD+CR组小鼠的视敏度(P＜0.05).MD+AL组小鼠PSD95、GAP-43、SYP的表达均明显低于正常组和MD+CR组小鼠(P＜0.05).MD+AL组小鼠视皮质中IGF-1 mRNA水平较正常组和MD+CR组显著降低(P＜0.05).结论:CR能改善成年MD弱视小鼠视觉功能,增加视皮质中可塑性相关蛋白的表达,重新激活视皮质可塑性,其机制可能与其调节IGF-1的表达有关.%Objective:To investigate the effect of caloric restriction on the plasticity of the visual cortex in monocular-deprived adult amblyopic mice,and to explore possible molecular mechanisms.Methods:This was an experimental study.A total of 54 neonatal healthy Kunming mice were randomly divided into 3 groups:a control group (n=18),a monocular deprivation+ad libitum (MD+AL) group (n=18),and a monocular deprivation+caloric restriction (MD+CR) group (n=18).MD model of mice was established at postpartum 21 days,and deprivation factors were removed at postpartum 35 days.At their postpartum 63 days,visual acuity and electrophysiological tests were used to detect visual function changes,and the expression levels of the proteins involved in plasticity in the visual cortex (postsynaptic density 95,PSD95;synaptophysin,SYP;growth-associated protein 43,GAP-43) were measured by immunohistochemistry and Western Blot.Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the expression level of the insulin-like growth factor-1 (IGF-1).Two-way repeated measurement analysis was used to compare data from each group.Results:The final numbers for the control group,MD+AL group and MD+CR group were 14,18 and 18 mice,respectively.The percentage of weight increase in the MD+CR mice was significantly lower than the percent increase in the MD+AL group (P＜0.05) from the beginning of the first week.The visual acuity of the MD+AL group was significantly lower than the acuity in both the control and MD+CR groups (P＜0.05).The expression levels of the three synaptic-associated proteins (PSD95,SYP,GAP-43) in the MD+AL group were all lower than levels in the control and MD+CR groups.RT-PCR showed the level of IGF-1 mRNA in the MD+AL group was significantly lower than the level in the control and MD+CR groups (P＜0.05),but increased significantly in the MD+CR group (P＜0.05).Conclusions:CR can improve the visual function of adult MD mice,increase the expression of synapse-related proteins in the visual cortex,and reactivate the plasticity of the adult visual cortex.Further research shows IGF-1 may be involved in regulating these effects.