Lithium chloride promotes lipid accumulation through increased reactive oxygen species generation

Abstract

LiCl is widely prescribed for bipolar disorder but adversely associated with a higher incidence of increased body weight. Here, we investigated effects and underlying mechanisms of LiCl on lipid accumulation. LiCl induced dose-dependent lipid accumulation in HepG2 and RAW264.7 cells under normal as well as high glucose conditions. LiCl exposure additionally promoted lipid accumulation in livers of zebrafish. SB216763, a specific GSK-3β inhibitor, did not affect lipid accumulation in HepG2 cells. Expression of key lipogenic enzymes, such as FAS and aP2, as well as SR-B1 were increased in RAW264.7 cells. LiCl enhanced FAS, ACC and SCD-1 mRNA levels while suppressing CPT-1 in HepG2 cells. LiCl stimulated DNA binding activities of SREBP-1c and ChREBP. LiCl activated AMPK phosphorylation but the AMPK inhibitor, AICAR, did not suppress LiCl-induced lipid accumulation in RAW264.7. LiCl, but not SB216763, induced a significant increase in ROS in RAW264.7 and HepG2 cells. NOX activity was dose-dependently enhanced by LiCl. Furthermore, NOX-1, NOX-2 and DUOX-1 mRNA levels were upregulated at an early stage of LiCl stimulation. LiCl-induced lipid accumulation was suppressed by the antioxidant, NAC, and inhibitors of NOX, DPI and APO. Phosphorylation and transcriptional activity of CREB were enhanced by LiCl. The cell-permeable cAMP analog, di-butyryl cAMP, not only promoted lipid accumulation itself but also LiCl-induced lipid accumulation in RAW264.7 cells. H-89, a PKA inhibitor, suppressed CREB activation, lipid accumulation and NOX activity in RAW264.7 cells. Our results indicate that LiCl stimulates lipid accumulation in hepatocyte and macrophage cells potentially through increased PKA-dependent ROS production.