Synaptic released zinc promotes tau hyperphosphorylation by inhibition of protein phosphatase 2A (PP2A).

Hyperphosphorylated tau is the major component of neurofibrillary tangles in Alzheimer disease (AD), and the tangle distribution largely overlaps with zinc-containing glutamatergic neurons, suggesting that zinc released in synaptic terminals may play a role in tau phosphorylation. To explore this possibility, we treated cultured hippocampal slices or primary neurons with glutamate or Bic/4-AP to increase the synaptic activity with or without pretreatment of zinc chelators, and then detected the phosphorylation levels of tau. We found that glutamate or Bic/4-AP treatment caused tau hyperphosphorylation at multiple AD-related sites, including Ser-396, Ser-404, Thr-231, and Thr-205, while application of intracellular or extracellular zinc chelators, or blockade of zinc release by extracellular calcium omission almost abolished the synaptic activity-associated tau hyperphosphorylation. The zinc release and translocation of excitatory synapses in the hippocampus were detected, and zinc-induced tau hyperphosphorylation was also observed in cultured brain slices incubated with exogenously supplemented zinc. Tau hyperphosphorylation induced by synaptic activity was strongly associated with inactivation of protein phosphatase 2A (PP2A), and this inactivation can be reversed by pretreatment of zinc chelator. Together, these results suggest that synaptically released zinc promotes tau hyperphosphorylation through PP2A inhibition.

[Research on cytokines gene express of rats alcoholic liver disease affected by tea polyphenol].

OBJECTIVE: To evaluate the effect of tea polyphenol(TP) on the rat with alcoholic liver damage. METHOD: Rats were divided into 3 groups, in which 2 groups were stomach perfused with alcohol to result in ALD, and 1 group of them stomach perfused with TP simultaneously. Another group was normal control groups (stomach perfused with drinking water). In the end of 12 weeks, the liver specimen of each rat was observed by anglicizing its tissue damage, and all data collected was performed by statistical analysis in quantum and semi-quantum. Meanwhile cytokines gene express of each group is determined. RESULT: In the end of 12 weeks, alcoholic hepatitis appeared in rat liver. Hepatic injury in alcohol group and TP group were found, but could not be found in normal group. Compared with pure alcohol group, alcoholic liver damage mainly showing with steatosis in TP group were slight, in addition showing liver cellular swelling with small area, with less spot and focal necrosis, none bridging necrosis. Steatosis were slight relatively, mega-bubble steatosis were less found. Collagen deposition of TP group were less than those of pure alcohol group. Gene expression of. cytokine have diversity statistically such as IL-3, IL-4, IL-1R2, IL-6R, IL-7R2, IL-3Ra, IL-R1, IL-13, IL-1R1, IL-7R2, EPO-R, LIFR, IL-1R2, IL-5R2, CSF1, CD27, IL-6R. CONCLUSION: TP is able to attenuate alcoholic liver damage. It's mechanism is possibly due to modulating cytokines gene expression of cytokine.