This invention provides a method for regulating migration of neuronal
progenitor cells in the nervous system of a mammal. The method comprises
providing a mammal with TNR, a biologically active fragment of TNR, or a
TNR agonist in an amount sufficient to direct migration of the neuronal
progenitor cells. The invention provides a method of treating
neurological diseases by replenishing diseased, damaged, or destroyed
neural cells in the central nervous system or in the peripheral nervous
system.