Total protein extracted from brain microvessels obtained from 6, 12, 18 and 24 rats was resolved with 12% SDS-PAGE gel. MnSOD and GAPDH were detected with specific antibodies. Lower panel shows the relative intensity of bands of MnSOD to GAPDH. Data are mean ± SD from 3 experiments. **p < 0.01 vs. 6 months; ***p < 0.001 vs 6 months.