Soluble beta-amyloid impaired the GABA inhibition by mediating KCC2 in early APP/PS1 mice

Alzheimer's disease (AD) is a neurodegenerative disorder, which has become the leading cause of dementia cases globally. Synaptic failure is an early pathological feature of AD. However, the cause of synaptic failure in AD, especially the GABAergic synaptic activity remains unclear. Extensive evidence indicates that the presence of soluble amyloid-beta is an early pathological feature in AD, which triggers synaptic dysfunction and cognitive decline. Our recent study explored the relation of GABAergic transmission and soluble A beta in early APP/PSI mice. Firstly, we found soluble A beta 42 levels were significantly increased in serum, hippocampus and prefrontal cortex in 3-4 months APP/ PS1 mice, which was much earlier than A beta plagues formation. In addition, we found TNF-alpha and BDNF expression levels were increased. while KCC2 and GABA(A)R expression were decreased in 3-4 months APP/PS1 hippocampus. When we treated 3-4 months APP/PS1 mice with a potent gamma-secretase inhibitor, LY411575, which can reduce the soluble A beta 42 levels, the TNF-alpha and BDNF protein levels were decreased, while KCC2 and GABA(A)R levels were increased. In conclusion, our study suggested soluble A beta may impaired the GABA inhibition by mediating KCC2 levels in early APP/PS1 mice. KCC2 may be served as a potential biomarker for AD.