Immunochemical detection of the mineralocorticoid receptor in rat brain.

The mineralocorticoid receptor (MCR) in the brain of adult male rats was analyzed with the aid of an antiserum generated by immunizing rabbits with this protein purified biochemically from rat kidney. In Western blots, the antibody recognized a single band of protein of about 98 kD from all target tissues studied to date. The granular cells in the cerebellum appeared to be the richest region of the central nervous system in the MCR analyzed by dot blots and by immunoperoxidase staining. High immunoreactivity was also observed in the dorsal and ventral hippocampus, as well as the anterior, mediobasal and posterior hypothalamus. In contrast, midbrain, septum and striatum were MCR-negative. The antibody macroaggregated and precipitated brain MCR labelled with 3H-aldosterone but did not recognize 3H-RU 26752 bound nonspecifically to non-MCR proteins in whole brain cytosol. Thus, MCR function and expression in the adult rat brain need to be reassessed.