Effects of Shen-wu Capsule and Its Effective Component Tetrahydroxystilbene Glucoside on Synaptophysin Expression in Hippocampal Neurons of Aged Rats

Objective To observe the effects of Shen-wu capsule(SW) and its effective component tetrahydroxystilbene glucoside(TSG) on synaptophysin expression in hippocampal neurons of aged rats,and to elucidate the mechanisms of their effects in prevention and treatment in neurodegenerative diseases.Methods SW(0.8 g/kg,1.6 g/kg) and TSG(0.03 g/kg,0.06 g/kg) were intragastrically administered to aged Sprague-Dawley rats which were 21 to 24 months old for 3 months.Six-month-old rats were used as young control group,and vehicle-treated 24-month-old rats as aged control group.The straight-channel water maze test was used to evaluate the learning and memory ability in rats.Electron microscopy was used to observe neuronal ultrastructure in hippocampus CA1 area especially the synaptic structure.The expression of synaptophysin(SYP) in hippocampus was detected by immunohistochemical staining.Results Compared with 6-month-old young control group,the number of errors in the water maze test increased in aged control rats at the age of 24 months(P0.01);and administration of high dose of SW and TSG significantly reduced the number of errors in aged rats(P0.01).Electron microscopy displayed that the number of synapses in the hippocampus CA1 area clearly diminished in aged control rats,while high dose of TSG administration significantly increased the number of synapses,even formed synaptic-globes.Immunohistochemical staining showed that the expression of SYP in the hippocampus decreased markedly in aged control rats(P0.01),but significantly elevated in aged rats treated with SW(low and high doses) and TSG(high dose)(P0.01).Conclusion SW and TSG protected neuronal synaptic structures and enhanced synaptic protein expression in aged rats,which provided the experimental data for elucidating the anti-aging mechanisms of SW capsule and TSG.