TIMP1 and cardiovascular disorder: However, immediately following the 15-minute context re-exposure, rats previously exposed to witness stress exhibited significant increases in TIMP-1 levels, an early biomarker of increased cardiovascular disease risk [43–47], as compared with both control and intruder rats (effect of stress: F(2, 23) = 7.7, p<0.01; Average pg/mL ± SEM (n)): control: 12,272 ± 1419 (11); intruder: 10157 ± 1758 (8); witness: 23,317 ± 4140 (7)).