Injection of bradykinin or/and cyclosporine A to hippocampus induces Alzheimer-like phosphorylation of tau and abnormal behavior in rats / 中国病理生理杂志

ABSTRACT

Bradykinin (BK) is a calcium/calmodulin dependent protein kinase Ⅱ (CaMKⅡ) specific activator, and Cyclosporin A (CSA) is reported to suppress protein phosphotase (PP)-2B activity. In vitro studies have shown that CaMKⅡ and PP-2B play an important role in Alzheimer-like phosphorylation of microtube-associated protein tau. To reconstitute an animal model based on the imbalance of protein kinase (s) and protein phosphatase (s) seen in Alzheimer brain, we injected BK and/or CSA into rat hippocampus. The results from behavioral study showed that an obvious disturbance in learning and memory was seen with BK or BK plus CSA injected rats. Moreover, the behavior abnormality appeared earlier in aged rats than young adults of the same kind after the injection. On the other hand, no obvious dysfunction in living and behavior was observed with CSA alone injected rats. The results obtained by immunohistochemical assay indicated that the staining for M4\, 12E8\, PHF-1 and CaMKⅡ was stronger, and for Tau-1 was weaker in BK injected rats compared with Control group. It was also found that the binding of M4 and PHF-1 but not 12E8 to tau was significantly increased in CSA injected rats. As the same as BK injection, binding of Tau-1 to tau was decreased after CSA injection. The immunostaining for 12E8\,PHF-1 and CaMKⅡ was increased, whereas for Tau-1\, M4\, and GSK-3 was decreased after combination injection of BK and CSA. In addition, the staining of PP-2B decreased in all the three models. To our knowledge, this is the first data shown in vivo that the activation of CaMKⅡ induces both Alzheimer-like tau phosphorylation and behavioral disturbance.