Spinal cord regeneration in rats after immunosuppressive treatment. Theoretic considerations and histologic results

Some species of animals and some early developmental stages of other species are capable of central nervous system (CNS) regeneration. These species and developmental stages also have reduced or absent allergic reaction to tissue homografts. Mammals are allergic to their own brain antigens, and experimental allergic encephalomyellitis (EAE) can be produced when they are exposed to parenterally administered brain antigen. Immunosuppressive treatment will delay or prevent the production of EAE in rats. In our experiments, immunosuppressive treatment made possible the electrophysiologic study of regeneration of long descending motor tracts of the spinal cord in rats six months after spinal cord transection. Histologic evaluation showed no comparative difference in scar at the site of transection when treated animals were compared with controls. Neither was any difference noted between animals in which regeneration was shown electrophysiologically and those without such regeneration. Perhaps humoral antibodies play a role in the prevention of functional regeneration in the rat.