GRM5 and Anxiety: To determine if, besides NMDAR, other glutamate receptors also play a part in mediating the enhanced anxiety levels caused by vHPC astrocytic activation, we chose to target the metabotropic glutamate receptor 5 (mGluR5), which has been shown to mediate social isolation‐induced anxiety‐like behaviors in our previous study.[16] We found that intra‐vHPC application of the mGluR5 antagonist MPEP (20 × 10−6m) failed to improve anxiety‐like behaviors in vHPC astrocytes‐activated mice (Figure S9A–E, Supporting Information).