Postsynaptic mGluR mediated excitation of neurons in midbrain periaqueductal grey

► We examined postsynaptic mGluR actions in midbrain periaqueductal grey. ► Group I mGluR agonists activated most neurons, via mGluR1 and 5. ► Group II and II mGluR agonists inhibited a minority of neurons. ► Endogenously released glutamate also activated group I mGluR. ► These findings provide a basis for mGluR mediated analgesia in PAG.