Metabotropic glutamate receptor-mediated currents at the climbing fiber to Purkinje cell synapse.

Different forms of synaptic plasticity in the cerebellum expressed at the synapses onto Purkinje cells (PCs) are mediated by membrane metabotropic glutamate receptors (mGluRs). There are three main mGluR groups with a total of 8 subtypes. Although mGluRs are also found at the climbing fiber (CF) to PC synapses, the distribution and biological activity of their types is not well-known. Using whole cell patch-clamp recordings from PCs in rat cerebellar slices with inhibitors of ionotropic receptors and glutamate uptake blockers we demonstrate a complex pharmacology of currents obtained by CF stimulation. The mGluR1 specific antagonist CPCCOEt in a group of cells suppressed this response, but in a similar number of other cells it induced a potentiating effect. It was found that a switch between these two biopharmaceutical effects might occur with age.