Retinoid Signaling in the Central Nervous System

Vitamin A has long been known to be associated with function of the central nervous system (CNS) from its requirement as retinaldehyde, for phototransduction in the eye. One of the first extensive literature reviews of genes regulated by retinoic acid (RA) signaling suggested that several hundred gene targets of RA exist. RA is an effective promoter of neural differentiation and can induce a pluripotent stem cell line such as the embryonal carcinoma cell line P19 into both glial and neuronal lineages. Analysis of the differential expression of retinoid binding proteins and receptors in the brain provide a key to understanding the diversity of functional effects of retinoid signaling. The field of retinoid neurobiology is relatively new. Its late development may reflect the lack of strong behavioral changes in animals depleted of vitamin A. Currently, very strong evidence exists for retinoic acid to play a fundamental role in regulating neuronal plasticity.