GRM5 and epilepsy: While astrocytes in the adult brain are almost depleted of mGluR5 (Sun et al., 2013), the receptor is consistently expressed in chronic epilepsy models and resected tissue from patients with epilepsy (Aronica et al., 2000, 2003), and a recent study has shown that mGluR5 expression and mGluR5-dependent Ca2+ transients reemerge during epileptogenesis along with an increase in glutamate uptake (Umpierre et al., 2019).