Dopaminergic neurons from MAC1-deficient mice are more resistant to Aβ-induced neurotoxicity in vivo. Two μg of Aβ were injected into the right side of adult MAC1+/+ and MAC1-/- mouse SN; vehicle saline alone (control group) was injected into the left side. After 7 days, brains were removed, dopaminergic neurons were stained with an antibody against TH and the microglia were stained with an antibody against Iba-1. Ten animals were used for each group. Dopaminergic neurons were counted in a double-blind manner by three individuals. (A) Immunocytochemical analysis of TH-positive neurons. (B) Number of TH-positive neurons. (C) Immunocytochemical analysis of microglia. (D) Western blot analysis of microglial activation in midbrain area. GAPDH was used as loading control. (E) The ratio of densitometry values of Iba1 and GAPDH was analyzed and normalized to respective control. Results are presented as mean ± SEM. #: p < 0.05 compared with corresponding saline-treated side. *: p < 0.05 compared with MAC1+/+ mice after same treatments.