A novel <scp>DPP</scp>‐4 inhibitor Gramcyclin A attenuates cognitive deficits in <scp>APP</scp>/<scp>PS1</scp>/tau triple transgenic mice via enhancing brain <scp>GLP</scp>‐1‐dependent glucose uptake
Zongyang Li, Yuan Zhang, Xiangbao Meng, Min Li, Weiwei Cao, Junshan Yang, Xudong Xu, Wenlan Liu, Weiping Li, Qian Cai, Sicen Wang, Guoxu Ma, Zhiheng Liu, Guodong Huang
Abstract
Abstract Enhancing glucagon‐like peptide 1 (GLP‐1) signaling with a dipeptidyl peptidase IV (DPP‐4) inhibitor might exert protective effects on Alzheimer's disease (AD). We found that intragastric administration of Gramcyclin A (10, 20 and 40 mg/kg), a novel DPP‐4 inhibitor, for 3 months significantly reversed cognitive decline in APP/PS1/tau triple transgenic mice in a dose‐dependent manner. Gramcyclin A treatment markedly reduced Aβ plaques as well as the insoluble and soluble forms of Aβ40 and Aβ42 in the hippocampus of APP/PS1/tau mice. Treatment with Gramcyclin A remarkedly decreased the level of microglia and suppressed neuroinflammation in the hippocampus of APP/PS1/tau mice. Moreover, Gramcyclin A treatment could increase brain glucose uptake in APP/PS1/tau mice, as detected by 18‐fluoro‐2‐deoxyglucose ( 18 F‐FDG) micro‐positron emission tomography (micro‐PET) imaging. Furthermore, Gramcyclin A significantly increased expression of glucagon‐like peptide‐1 (GLP‐1), GLP‐1R, proliferator‐activated receptor gamma coactivator (PGC)‐1α and glucose transporter 4 (GLUT4), and inhibited insulin receptor (IRS)‐1 phosphorylation and tau hyperphosphorylation in the hippocampus of APP/PS1/tau mice. Collectively, Gramcyclin A conferred protective effects against AD via enhancing brain GLP‐1‐dependent glucose uptake. The DPP‐4 inhibitor Gramcyclin A might be a potential therapeutic drug for AD.