Interestingly, activation of mGluR5 in the IL with a PAM (VU0360172) increased background and evoked activity of IL neurons under normal conditions, whereas in the K/C arthritis pain model co-activation of endocannabinoid CB1 receptor with ACEA was required to restore the facilitatory effects of VU0360172 [92]. This evidence concerns the gene GRM5 and Arthritis.