| The amygdala is an important part of the limbic system involved in the formation of emotions,memory and cognition.Calcium / calmodulin-dependent protein kinase II,Ca MKII(Ca MKII)is abundantly expressed in the amygdala.?CaMK?-F89G is an important part of Ca MKII holoenzyme and plays an important role in learning and memory and synaptic plasticity.We have found that ?CaMK?-F89G overexpression reduced NMDA-dependent long-term depression(LTD)at thalamus – lateral amygdala pathway,but the mechanism is not clear.In this study,we use ?CaMK?-F89G-F89 G transgenic mice that created by genetic engineering and chemical knockout technique,in which exogenous ?CaMK?-F89G-F89 G was overexpressed in the forebrain,to investigate the mechanism of impairment in NMDAR-dependent LTD.The main results are as follows:1.AMPAR internalization and dephosphorylation,PP1/2A activity were impaired,and stargazin expression was increased in ?CaMK?-F89G-F89 G transgenic mice.We used western blotting and activity Assay Kit to detect the changes of molecules related LTD in amygdala after chemical-induced LTD.The results showed that the impaired PP1 and PP2 A activity and the increased stargazin lead to the impairment in internalization of AMPAR,the dephosphorylation of Glu A1 subunits Ser831 and Ser845 in ?CaMK?-F89G-F89 G transgenic mice.2.An excessive Akt activity and impaired GSK3? activity in ?CaMK?-F89G-F89 G transgenic mice.Western blotting results showed that during LTD formation,the phosphorylation of Akt-Thr308 and Ser473 at amygdala was higher in ?CaMK?-F89G-F89 G transgenic mice than in wild-type mice,and excessive Akt activity inhibited GSK3?-Ser9 dephosphorylation,decreased activation of GSK3? during NMDAR-LTD.3.MK-2206 partially recovered AMPAR internalization / dephosphorylation and the impaired NMDAR-LTD in Transgenic Mice.Western blotting showed that MK-2206(30?m),a specific Akt inhibitor,significantly decreased the phosphorylation of Akt-Thr308 and Ser473 in the amygdala of transgenic mice,reversed the activity of GSK3? during NMDAR-LTD,and partially recovered internalization of AMPAR and the dephosphorylation of Glu A1 subunits Ser831 and Ser845 in transgenic mice,partially reversed the impaired NMDAR dependent LTD in amygdala.Taken together,overexpression of ?CaMK?-F89G in the forebrain results in impairment of NMDAR-LTD in amygdala.It may be caused by reducing PP1/2A activity,increasing stargazing expression and impairing Akt-GSK3? signaling,consequently lead to impaired AMPAR internalization and dephosphorylation during NMDAR-LTD.Our data,for the first time,indicate that ?CaMK?-F89G plays an important role in NMDAR-LTD in amygdala and have provided new important evidence for revealing the mechanism of ?CaMK?-F89G in synaptic plasticity. |
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