Figure 1. GDF11/8 levels decline with age in both mice and humans. (A) ELISA shows GDF11 levels decline with age in the brain of aged mice (20-22-month-old), (B) reduced brain GDF11/8 expression in old mice was confirmed by Western blotting, (C) brain GDF11/8 (brown) positive cells decline with age in older humans. Hematoxylin (blue) counterstain. Mouse studies, n=5, human. Magnification 20X, n=8-9, *p<0.05, **p<0.01.