ABSTRACT
Aim To assess the effects of Trillium Tschonoskii Maxim ( TTM) decoction on learning and memory dysfunction in Alzheimer’ s disease ( AD ) model rats which induced by okadaic acid( OA) and its possible mechanism. Methods The SD rats were di-vided into ten groups,namely,d DMSO control group, OA group, TTM high-dose ( 0. 5 g·kg-1·d-1) group,TTM medium-dose ( 1 g·kg-1·d-1) group, TTM lower-dose (2 g·kg-1·d-1) group,and these groups were divided into one week and two weeks of gavage. Treatment groups were gavaged with TTM de-coction twice a day. After 5 days of Morris water maze training,treatment groups and AD model groups were injected with OA (0.392 mmol·L-1,1. 5 μL) in bi-lateral hippocampal of the rats. The DMSO groups were injected with 10% DMSO. The spatial memory reten- tion wereas detected by water maze at 24 h after injec-tion. After the test, we prepared sample for Western blot and Nissl’s staining. The Western blotting test was used to detect the PP2A activity and the phospho-rylation of Tau protein in the hippocampus. Nissl’'s staining was used to observe the changes of the number of Nissl’s bodies in the hippocampal CA1 and CA3 re-gions. Results The Morris water maze test showed that after injection of OA, the latency of TTM groups wereas shorter than that of OA groups. Western blot showed that the high dose TTM could increase the ac-tivity of PP2A and decrease the level of Tau phospho-rylation at PS-Tau396,,PT-Tau404. The Nissl’s stai-ning results showed that the number of Nissl’s bodies in the hippocampal CA1 and CA3 regions of OA groups wereas significantly attenuated compared with that of the number of Nissl's bodies in the hippocampal CA1 and CA3 regions than DMSO groups. The number of Nissl’s bodies in high groups were morewas larger than that of OA group. Conclusion The results show that TTM can improve the learning and memory dysfunction in AD model rats which induced by OA. The mecha- nism wasis probably that TTM can increase PP2A ac-tivity and then down-regulate the level of Tau phospho-rylation and improve neural development.
ABSTRACT
Aim To assess the effects of Trillium Tschonoskii Maxim ( TTM ) decoction on Tau protein phosphorylation and synaptic development in AD model rats induced by high activity GSK-3β. Methods The SD rats were divided into five groups of ten animals, named sham-operated group ( blank group) , AD model group, TTM group (0. 5, 0. 25, 0. 125 g·kg-1 · d-1 ) . Treatment group received gavage once a day for seven days with TTM decoction, while other groups by gavage once a day for seven days with drinking water. On 2nd day by gavage, Morris water maze test was used to assess the spatial learning and memory ability of the rats. After five days' training, rats in the treat-ment groups and AD model group were injected wort-mannin ( WT, PI3K specific inhibitor ) and GF-109203X (GFX, PKC specific inhibitor) (100 μmol ·L-1 of each, total volume of 10 μL) into the right lateral ventricle. Western blot was used to detect the levels of phosphorylation Tau protein at multiple sites and the expression level of PI3K, Akt, PKC, GSK-3β(S9, T216) and synapse-associated proteins. Immu-nohistochemical method was used to detect the hyper-phosphorylation of Tau protein in hippocampus of rats. Golgi staining was applied to detect the number and morphological changes of synaptic development and dendritic spines. Nissl' s staining was employed to ob-serve the development of neonatal neurons in hippo-campus and cortex. Results Western blot showed that the phosphorylation level of Tau in hippocampus increased in model group, and the activity of GSK-3βwas up-regulated. Among them, however, in middle dose TTM group, the phosphorylation level of Tau in hippocampus decreased and the activity of GSK-3βde-creased. The expression levels of p-PKC and p-Akt in low and middle dose treatment group were higher than those in model group, thus increasing the activity of PKC and Akt to inhibit the activity of GSK-3β kinase. Immunohistochemistry also indicated that TTM could decrease the biological effects of Tau phosphorylation in hippocampus of AD rats. Western blot showed that TTM could increase the expression levels of synapsin-1 , syn-aptophysin and GluR-1 in hippocampus of AD rats. Nissl staining showed that the number of Nissl bodies in hippocampal neurons of AD model group were signif-icantly fewer than those of sham operation group, which could be increased by TTM middle and high dose group, and the complexity and dendritic spine density of hippocampal neurons in AD rats could be en-hanced as well. Conclusion TTM can effectively im-prove the cognitive function of AD rats induced by the increase of GSK-3β activity, and its possible mecha-nism may be via down-regulating the activity of GSK-3β and inhibiting the phosphorylation of tau protein and promoting the development of neurons.