Furthermore, a combined usage of sub-effective dosage of LY341495 and ketamine was efficacious for the depression treatment without producing any ketamine-induced side-effects in patients (Agnieszka et al. 2019), suggesting that combination therapy using mGluR2/3 antagonist and ketamine can reduce the effective dosage of ketamine and its side-effects. Here, GRM2 is linked to major depressive disorder.