Immunohistochemical Characterization of the Orphan Nuclear Receptor RORα in the Mouse Nervous System

Abstract

RORα is an orphan nuclear receptor. A deletion mutation in the RORα gene leads to severe cerebellar defects, known as the staggerer mutant mouse. Although previous in situ hybridization (ISH) studies have shown that RORα is highly expressed in the cerebellum, especially in Purkinje cells, and in the thalamus, sufficient immunohistochemical (IHC) study has not yet been presented. I demonstrate here the IHC analysis of RORα using a specific anti-RORα antibody, in adult and developing mouse nervous system. RORα immunoreactivity was observed in the Purkinje cell and molecular layers of the cerebellum. The co-localization of RORα with calbindin D28K (CaBP) and parvalbumin indicates that RORα-positive cells were Purkinje cells, stellate cells, and basket cells. In addition to the cerebellum, strong to medium RORα immunoreactivity was found in the thalamus, cerebral cortex (mainly in the layer IV), dorsal cochlear nucleus (DCN), suprachiasmatic nucleus (SCN), superior colliculus, spinal trigeminal nucleus, and retina. The immunostaining was restricted in nuclei of neurons. Developmentally, RORα immunoreactivity was observed-in the cerebellum and thalamus from embryonal day 16 (E16). The distribution of RORα immunoreactivity and RORα mRNA hybridization signal was almost coincident. However, the intensity of hybridization signal was not always parallel to that of immunoreactivity.