Transient and compartmental expression of the reeler gene product reelin in the developing rat striatum

Mammalian neostriatum is composed of two neurochemically and neuroanatomically defined compartments, called the patches and matrix. The present study concerns a search for neurochemical molecules involved in formation of the striatal compartments. Using the monoclonal antibody CR-50, we here disclose a transient expression of the reeler gene product Reelin, which is known to play a crucial role in neuronal positioning and axon guidance during corticogenesis, in the developing striatum of rats. Furthermore, Reelin protein is differentially concentrated in the two distinct compartments showing a mosaic-like fashion in the early postnatal period: the compartments of heightened CR-50-immunolabeling correspond to so-called “dopamine islands” (i.e., developing striosomes) visualized by tyrosine hydroxylase (TH)-immunostaining. On the basis of these findings, we hypothesize that Reelin protein may play a role in developmental organization of the striatal compartments.