APP and Alzheimer disease: Moreover, a metabolomics study in 2017investigating the changesin urine metabolites between APP/PS1 mouse models and wild type controls47 revealed 24 differential expressed metabolites.One of the metabolites highlighted was 4-guanidinobutanoic acid, adownstream product of arginase metabolism.48 It was found that 4-guanidinobutanoic acid was upregulated in APP/PS1mouse urine samples implying NO production may be dysregulated inthese AD models and contribute to neurodegenerative processes withinAD.47