GRM2 and drug dependence: With respect to isolated effects of receptor subtypes regarding psychostimulant addiction, mGluR2 was found to be key in mediating cocaine addictive behavior (Cannella et al., 2013), whereas activation of mGluR3 and/or inhibition of mGluR2 signaling has been proposed to be beneficial in the treatment of methamphetamine-addiction (Busceti et al., 2021).