Histological and biochemical examination of various organs following NBD-PZ enema. (A) HE stain of the colon obtained from a BALB/c mouse at 24 hours after intrarectal administration of 100 μl PBS containing 2.5 μg/ml NBD-PZ. Bar, 200 μm. (B) ALT and BUN concentrations in the plasma obtained from BALB/c mice at 24 hours after the enema of 2.5 μg/ml NBD-PZ. Data represent the means ± standard deviations (n = 5).