To examine whether IP injection of HNG could affect signaling in the hippocampus of mice, which could support the enhanced cognitive function in AD mice, we injected humanin into young (12 weeks) and old (18 months) C57BL/6 male mice for 2 weeks and dissected the hippocampus and hypothalamus for immunoblotting. Here, MT-RNR2 is linked to Alzheimer disease.