AUTORADIOGRAPHY OF T-ACPD-SENSITIVE [H-3] GLUTAMATE BINDING-SITES IN MOUSE CEREBELLUM DURING ONTOGENY

This study provides the first evidence in cerebellum for the distribut ion of [H-3]-Glutamate ([H-3]-Glu) binding sites which could correspon d to EAA metabotropic receptors. In the adult these sites are more abu ndant in the molecular layer (ML) than in the internal granular layer (IGL) and very scarce in the deep cerebellar nuclei (DCN). In the deve loping cerebellum binding site changes followed distinct ontogenic pat terns in each cerebellar layer : t-ACPD-sensitive [H-3]-Glu binding si te density increased in the ML and decreased in the IGL and in the DCN . t-ACPD-sensitive [H-3]-Glu binding sites were different from those s ensitive to CPP, a NMDA antagonist, or to CNQX, a compound acting on t he AMPA/Kainate receptors. The transient expression of these sites in the DCN and in the IGL during ontogeny suggests that they play a speci fic role in cerebellar development at a specific developmental stage, but further pharmacological and functional characterization of the act ivated second messenger cascade might help in clarifying the nature of this role.