Plasma concentrations in Aldh7a1-KO mice (n = 4) compared to WT mice (n = 4) of (A) 6-oxoPIP, and (B) the sum of 2S,6S-2-OPP and 2S,6R-2-OPP. Mean and interquartile ranges are shown. KO levels were significantly increased compared with WT (Mann-Whitney U test, P < 0.05). Extracted-ion chromatograms in brain tissue extract of Aldh7a1-KO mice of (C) P6C, m/z 128.0706, retention time (RT) 0.93 minutes, (D) α-AASA, m/z 146.0812, RT 0.93 minutes, (E) 2S,6S-2-OPP, m/z 186.1125, RT 2.46 minutes, (F) 6-oxoPIP, m/z 144.0652, RT 3.18 minutes, and (G) pipecolic acid, m/z 130.0863, RT 1.06 minutes. Representative data from 1 out of 2 Aldh7a1-KO brain samples is shown. The y axis represents relative NGMS intensity, and the x axis represents RT (minutes).