PLASMA NERVE GROWTH-FACTOR ACCESS TO THE POSTNATAL CENTRAL-NERVOUS-SYSTEM

The accessibility of macromolecules to the postnatal mammalian central nervous system is a subject of controversy and importance. One of the biologically important macromolecules in neural development, nerve growth factor (NGF), is thought to be unable to cross the blood-brain barrier in postnatal mammals. In this study, I-125 labeled 7S NGF was systemically administered to postnatal rats and was found to accumulate in the brain in significant levels. In addition, brains from saline perfused rats contained intact 7S NGF as determined by gel autoradiography. Radiolabeled NGF was found to be localized to specific areas corresponding to p75 NGF receptor distribution in the hippocampus and cortex by autoradiography. Circulating plasma NGF has access to the developing postnatal neuraxis where it may exert a humoral trophic function.