HTT and Huntington disease: The prolonged pharmacological blockade of mGluR5 signaling with the negative allosteric modulator CTEP (2-chloro-4-[2-[2,5-dimethyl-1-[4-(trifluoromethoxy)phenyl]imidazol-4-yl]ethynyl]pyridine) also improves HD symptoms and promotes autophagic removal of mutant huntingtin aggregates in the brains of zQ175 HD mouse model (Abd-Elrahman et al., 2017; Abd-Elrahman and Ferguson, 2019).