GRM5 and Alzheimer disease: Similarly, although translation of findings from animals into humans is relatively unsuccessful because animal models do not faithfully reproduce AD pathology, studies of postmortem human brain tissue also showed no changes in the expression level of mGlu5, Gq/11 and PLCβ1 in the cerebral cortex in AD, although decreased binding to mGlu receptors and mGlu1 expression was reported [44].