Analysis of changes in triacylglycerol ratios in mouse liver and plasma in response to a liver X receptor agonist

Abstract

An LC-MS method was developed for the analysis of triacylglycerols (TAG) in mouse liver extracts and plasma samples. C57 Mice were treated with two LXR agonists that have been shown to upregulate TAGs, T0901317 (T1317) or Org 264693 and compared to vehicle dosed animals. The dose used was 30 mg kg(-1), once daily, with three different dose regimes; 24 H, 48 H and 5 day. The TAG ratios measured were C52: 2/C54: 3 and C52: 3/C54: 4, which corresponded to a decrease in the palmitate and an increase in oleate composition of the TAGs. A significant change in the C52: 2/C54: 3 ratio was observed with all dose regimes and a good correlation was obtained between liver and plasma samples. In a separate study, the same compounds were dosed to LXR alpha and LXR beta knock-out (KO) mice at 30 mg kg(-1), once daily, for 5 days. The LXR beta KO mice showed similar TAG ratio changes to the C57 mice, whereas the LXR alpha KO mice showed no change in TAG ratios versus vehicle dosed animals. Measurements of lipid liability in response to an LXR agonist are typically made by measuring total liver TAG levels, which here, only showed a significant effect after the 48 H and 5 day dose regimes. By using a ratio measurement analysis could be performed on plasma samples, greatly simplifying the sample preparation procedure, without the requirement for either calibration curves or an internal standard

The C57BL/6J Niemann–Pick C1 mouse model with decreased gene dosage has impaired glucose tolerance independent of body weight

“…The dried lipid extract was suspended in water containing 2% Triton X-100 and the concentration of total cholesterol (cholesterol and cholesteryl ester), triacylglycerol, and free fatty acids was determined using the colorimetric enzymatic kits as previously described (Scullion et al, 2012). …”

The Medicinal Chemistry of Liver X Receptor (LXR) Modulators

“…Researchers at Organon discovered a series of compounds illustrated by 19 – 21 . The potency of 19 has not been disclosed, but in an in vivo study, the compound was dosed orally to mice at 30 mg/kg for 5 days, leading to changes in the composition and degree of unsaturation of triglycerides . Compounds 20 and 21 have LXRβ K i values of 2.1 and 2.8 nM, respectively .…”

“…119 The potency of 19 has not been disclosed, but in an in vivo study, the compound was dosed orally to mice at 30 mg/kg for 5 days, leading to changes in the composition and degree of unsaturation of triglycerides. 120 Compounds 20 and 21 have LXRβ K i values of 2.1 and 2.8 nM, respectively. 121 It is likely that the interaction of the hexafluoroisopropyl alcohol with His435 seen in 1 is retained in 19−21; however, movements of side chains, such as Phe329, expanding the binding pocket in the direction of H1 can be anticipated to accommodate these longer ligands.…”