Nucleus accumbens single-unit activity in freely behaving male rats during approach to novel and non-novel estrus

Metabotropic glutamate receptors (mGluRs) were previously shown to mediate a postsynaptic late propagation component elicited by layer Ib stimulation in guinea pig piriform cortex slices. In the present study, the effects of some group specific or subtype specific mGluR antagonists on the late propagation component were investigated using an optical imaging method, in order to identify mGluR subtypes mediating it. A selective mGluR1 antagonist (RS)-1-aminoindan-1,5-dicarboxylic acid most effectively suppressed the late component whereas a selective mGluR5 antagonist, selective group II or group III antagonists showed little or no suppressive effect. These results suggest that the late propagation component is mediated by mGluR1.