Docosahexaenoic acid, a ligand for the retinoid X receptor in mouse brain

The retinoid X receptor (RXR) is a nuclear receptor that functions as a lig and-activated transcription factor. Little is known about the Ligands that activate RXR in vivo. Here, we identified a factor in brain tissue from adu lt mice that activates RXR in cell-based assays. Purification and analysis of the factor by mass spectrometry revealed that it is docosahexaenoic acid (DHA), a long-chain polyunsaturated fatty acid that is highly enriched in the adult mammalian brain. Previous work has shown that DHA is essential fo r brain maturation, and deficiency of DHA in both rodents and humans Leads to impaired spatial Learning and other abnormalities. These data suggest th at DHA may influence neural function through activation of an RXR signaling pathway.