Study on Permeability of β-NGF Through Blood Brain Barrier by ~(125)I Tracing

β-NGF is extracted from fetus brain by centrifugation, dialyzing and ion-exchange chro-matography. The molecular weight of β-NGF is 13 kD detected by SDS-PAGE electrophoresis; the isoelectric point of β-NGF are 9. 0,9. 2 and 9. 3 respectively detected by isoelectrifocusing electrophoresis; the β-NGF shows the effect of stimulating neurite growth by PC12 cells culture. Using the 125I tracing technique, the animal experiments indicate (2. 41± 0. 12)% of injected 125I-β-NGF could go through the blood brain brrier at 15 min, and increase to (4. 20±0. 07)% at 30 min. The results provides scientific basis for research of β-NGF in clinical therapeutic application.