Antagonism of mGluRs has been proposed as a rational therapy for FXS [35], and preclinical studies have shown that mGluR5 antagonists can partially correct some abnormal behaviors in Fmr1-null mice, including increased open-field exploration, impaired rotarod performance, and decreased prepulse inhibition, although results have been mixed [18,36,37]. This evidence concerns the gene GRM5 and fragile X syndrome.