Further studies on the immunohistochemical localization of alpha-MSH in the rat brain.

Using two different specific antisera directed against alpha-melanocyte-stimulating hormone (alpha-MSH), the immunoperoxidase localization of alpha-MSH was performed on sections of the rat brain. With one antiserum, some nerve fibers stained for alpha-MSH were seen close to the apex of ependymal cells near the lumen of the lateral and third ventricles. With the other antiserum, alpha-MSH positive nerve fibers were localized in the pai mater. These results indicate that two different specific antisera directed against a same nolecule can probably recognize different antigenic sites of this molecule. Our findings also suggest a possible source of release for the alpha-MSH present in the cerebrospinal fluid (CSF).