Injection of bradykinin or cyclosporine A to hippocampus induces Alzheimer-like phosphorylation of Tau and abnormal behavior in rats

Objective To reconstitute an Alzheimer's disease model by administering bradykinin (BK) or cyclosporine A (CSA) to the rat hippocampus. Methods BK or CSA was administered to the rat hippocampus using a stereotaxic apparatus. The behavior of the rats was observed with an electronic attack-jump platform. The phosphorylation of Tau protein was examined through immunohistochemical assay. Results Behavior studies showed that an obvious disturbance in learning and memory was seen in BK injected rats. No obvious dysfunction was observed in CSA injected rats. The results obtained by immunohistochemical assay indicated that the staining of M4, 12E8, paired helical filament-1 (PHF-1) and calcium/calmodulin-dependent protein kinase II (CaMK II) was stronger, and that of Tau-1 was weaker in BK injected rats compared with the control group. We also found that the binding of M4 and PHF-1 but not 12E8 to Tau was significantly increased in CSA injected rats. As for BK injection, binding of Tau-1 to Tau was decreased after CSA injection. Conclusion To our knowledge, this is the first data showing in vivo that the activation of CaMK U induces both Alzheimer-like Tau phosphorylation and behavioral disturbances.