<b>DISTRIBUTION OF RETINOIC ACID RECEPTOR β PROTEINS IN RAT BRAIN: UP-REGULATION BY RETINOIC </b><b>ACID </b>

Abstract

While retinoic acid is known to be involved in the neurogenesis of embryos, little is known about its function in the adult brain despite the fact that many retinols and retinoic acid binding activities were detected in the extracts from mature rat brain. Furthermore, retinoic acid that was injected into peritoneal cavities was incorporated into the brain as well as into the testis and liver. By using immunoblot analyses with specific antisera against three retinoic acid receptors, α, β and γ, we demonstrated that the β type is the main retinoic acid receptor expressed in the mature rat brain. Retinoic acid receptor β proteins were expressed at a higher level in the cerebral cortex, striatum and cerebellum than in the other regions, and low levels were found in the limbic