Fig. 8. Hypothetical pathway by which nitrous oxide plus isoflurane induces apoptosis and Aβ generation. Nitrous oxide plus isoflurane induces apoptosis. Apoptosis, in turn, increases BACE levels, which serves to facilitate APP processing and increase Aβ generation. Elevated Aβ generation then further induces apoptosis, leading to another round of nitrous oxide plus isoflurane–induced apoptosis and Aβ generation. Aβ=β-amyloid protein; APP = amyloid precursor protein; BACE =β-site amyloid precursor protein-cleaving enzyme.