The mGluR8 receptor is detected in the olfactory bulb, thalamus, pontine gray, cerebral cortex, hippocampus, cerebellum, and retina3. Electrophysiological studies suggest that mGluR8 functions as a presynaptic autoreceptor to regulate glutamate release from the lateral perforant path terminals in the mouse dentate gyrus. It is suggested that mGluR8, like other group III mGluRs, controls glutamate release by inhibiting voltage-gated Ca2+ channels.nTargeted deletion of the mGluR8 gene in mice produces subtle behavioral alterations such as reduced habituation to novelty, hyperactivity, context-dependent but not cue-dependent disruption of the freezing response in the fear conditioning test, and increased anxiety.