APJ combined with apelin can regulate multiple signaling pathways such as cyclic adenosine monophosphate (cAMP) that are critically correlated with BDNF transcription (O’Carroll et al., 2013; Bortolato et al., 2016), manifesting potential involvement of BDNF in anti-AD-like effect of apelin-13. This evidence concerns the gene BDNF and Alzheimer disease.