The Girk2 ( wv ) (weaver) mutation impairs migration of cerebellar granule cells from external to internal granular layer and induces neuronal death during the first 2 weeks of postnatal life. Kainate receptors are heteromeric ionotropic receptors of glutamate consisting of five subunits termed GluR5, GluR6, GluR7, KA1 and KA2. In order to investigate whether the weaver gene affects the expression of kainate receptors in weaver cerebellum, we determined mRNA expression levels of GluR6 kainate receptor subunit and [(3)H]kainic acid specific binding in the developing cerebellum, using in situ hybridization and receptor film autoradiography, respectively. In the weaver postnatal day 10 (P10) cerebellum, our data indicated lower levels of GluR6 mRNA expression and lower [(3)H]kainic acid specific binding in external granular layer (EGL) compared to normal EGL. Our results are indicative of either down-regulation of kainate receptors or modulation of their functional characteristics in weaver granule cells.