GRM8 and Anxiety: An mGlu8 receptor-preferring agonist, 2-amino-2-(4-phosphonophenyl)acetic acid (RS-PPG), provokes dose-dependent antidepressant-like effects in the FST following central administration, while the mGlu8-selective PAM 2-[(4-bromophenyl)methyl-sulfanyl]-N-(4-butan-2-ylphenyl) acetamide (AZ12216052) decreases levels of anxiety in both the EPM and open-field tests (Duvoisin et al., 2010).