Presence of an alpha-melanocyte-stimulating hormone-like epitope in the 150,000 dalton neurofilament subunit from diverse regions of the central nervous system: an immunohistochemical and immunoblot study in guinea pig.

Monoclonal antibodies specific for the two higher molecular weight neurofilament (NF) subunits (NF200 and NF150), and antiserum to alpha-melanocyte-stimulating hormone (alpha-MSH) were used to probe the distribution of an alpha-MSH-like epitope in NF proteins of the guinea pig central nervous system using immunoblot and immunohistochemical methods. The anti-alpha-MSH antiserum recognized the same protein band as an anti-NF150 monoclonal antibody in immunoblots of proteins extracted from guinea pig cerebellum, spinal cord, retina, optic nerve, and neurohypophysis; it also stained axons and dendrites in sections of cerebellum, retina, and optic nerve. Although all cells of the pars intermedia and some in the pars distalis exhibited immunoreactivity with this antiserum, it did not stain axons in the neurohypophysis. Our immunoblot data demonstrate an alpha-MSH-like epitope in NF150 extracted from each of the regions studied. The lack of in situ recognition of this alpha-MSH-like epitope in neurophypophyseal axons, using the same immunohistochemical methods that demonstrate this epitope in axons of the cerebellum, retina, and optic nerve, suggests that NF150 is immunochemically heterogeneous in different regions of the guinea pig central nervous system.