Loss of testicular orphan receptor 4 impairs normal myelination in mouse forebrain

Testicular orphan nuclear receptor 4 (TR4) has been suggested to play important roles in the develop-ment and functioning of the central nervous system (CNS). We find reduced myelination in TR4 knockout (TR4/) mice, which is particularly obvious in fore-brains and in early developmental stages. Further analysis reveals that CC-1-positive (CC-1) oligo-dendrocytes are decreased in TR4/ forebrains. The O4 signals are also reduced in TR4/ fore-brains when examined at postnatal d 7. However, the number and proliferation rate of platelet-derived growth factor receptor -positive (PDGFR) oligo-dendrocyte precursor cells (OPCs) remain unaf-fected in these regions, suggesting that loss of TR4 interrupts oligodendrocyte differentiation. This is fur