GRM5 and Alzheimer disease: More and more evidence shows that glutamate mediated neurotoxicity is involved in the pathogenesis of AD, and this metabolic glutamate receptor (GRM5), whose signal transduction will activate the second messenger system of calcium phosphatidyl inositol, will also participate in the regulation of neural network activity and synaptic plasticity, which makes us speculate that GRM5 may be a very promising target for exploring treatment and improving AD disease (Danysz and Parsons, 2003; Doraiswamy, 2003; Tanović and Alfaro, 2006; Świetlik et al., 2022).