Class I mGlu receptor antagonist 1-aminoindan-1,5-dicarboxylic acid blocks contextual but not cue conditioning in rats

It is widely believed that metabotropic glutamate (mGlu) receptors play a potential role in memory formation. However, the particular function of different classes of mGluRs, or even subtypes, remains elusive. We show here that intraperitoneal injection of the class I selective antagonist 1-aminoindan-1,5-dicarboxylic acid (AIDA) in concentrations of 0.18 or 1.8 mg/kg 25 min prior to acquisition training blocks hippocampus-dependent contextual. but not hippocampus-independent cue, conditioning in rats. These data provide the first evidence for a specific role of mGlu receptors, class I in particular, in hippocampus-dependent learning tasks.