Beneficial effect of amyloid beta after controlled cortical impact

Background: Worse functional outcomes after controlled cortical impact (CCI) in Bace1−/− mice have previously been demonstrated. This study investigated whether reconstitution of amyloid-beta (Aβ) after CCI in Bace1−/− animals would reverse the detrimental effect of Bace1 deletion.Methods: Bace1−/− and wild type Bace1+/+ (C57Bl/6) mice were subjected to CCI (n = 14–23/group) or sham injury (n = 6/group). After injury, mice underwent intracerebroventricular injections of Aβ40 (n = 23 Bace1−/− and 17 Bace1+/+ per group) or vehicle (n = 14 Bace1−/− and 22 Bace1+/+ per group). Functional outcomes were assessed with wire grip (motor) and Morris water maze (spatial memory). Soluble Aβ levels were assessed at 24 hours and 21 days after CCI. Lesion volume was assessed 21 days after injury.Results: At 24 hours after injury, Aβ-treated Bace1−/− mice had Aβ40 levels similar to vehicle-treated Bace1+/+ mice, but by 21 days after injury there were no differences between Aβ-treated versus vehicle-treated Bace1−/− mice....