Abstract
OBJECTIVES: To assess the effect of the Modified Gandou Decoction (MGDD, developed based on the TongFuYangSui strategy in traditional Chinese medicine) for improving cognitive function in a PKR-silenced Wilson's disease (WD) TX mouse model and explore the underlying mechanism. METHODS: Thirty-six TX mice were randomized into TX group, TX+MGDD group, C16 group, and C16+MGDD group. In C16 and C16+MGDD group, the mice received daily intraperitoneal injections of 300 μg/kg C16 (a PKR inhibitor) for 30 days, and saline injections were given in the other two groups; after WD modeling, the mice in TX+MGDD and C16+MGDD groups received MGDD gavage for 4 weeks, while the other two groups were given saline gavage. After the treatments, the mice were examined using behavioral tests, followed by immunofluorescence staining, TUNEL staining, TEM, RT-qPCR and Western blotting analysis of the brain tissue. RESULTS: In behavioral tests, the mice in C16+MGDD group showed significantly shorter time spent in the perimeter than those in C16 group without significant differences in other parameters. Immunofluorescence staining revealed obviously lowered hippocampal oxidative stress level in C16, TX+MGDD, and C16+MGDD groups compared with TX group. Both MGDD and C16 treatment alone increased the number of hippocampal synapses and vesicles and improved ultrastructural synaptic damages, but their combination exhibited no synergistic effect. The C16+MGDD group showed significantly higher expressions of PSD93, PSD95, synapsin1 and synaptophysin than C16 group, but had comparable PSD93 expression with TX+MGDD group. While the mRNA expressions in the PKR/eIF2α pathway were similar between C16+MGDD and C16 groups, the protein levels of P-eIF2α and CHOP were significantly lower and P-CREB protein level was higher in C16+MGDD group. CONCLUSIONS: MGDD improves cognitive dysfunction in WD TX mice possibly by inhibiting the PKR/eIF2α pathway, promoting expressions of synaptic proteins, and improving synaptic structure and function.