Although it is well recognized that adiponectin plays a key role in lipoprotein-lipid metabolism, the specific mechanisms that underlie these associations are poorly understood. In this regard, Qiao et al. investigated the effects of adiponectin on VLDL triglyceride metabolism by increasing plasma adiponectin levels in mice through Ad-mACRP30 adenovirus injections. In treated mice, plasma adiponectin levels increased twelvefold. As a consequence, fasting plasma triglyceride levels decreased by 40% and hepatic mRNA levels of apolipoprotein B were also considerably decreased. Hepatic mRNA levels of apolipoprotein B were also decreased in vitro in HepG2 cells incubated with recombinant adiponectin. In differentiated C1C12 myotubes, recombinant adiponectin increased lipoprotein lipase (LPL) expression. In Ad-mACRP30-treated mice, a significant increase in postheparin LPL activity was also reported. Although this hypothesis remains to be tested, the authors suggested that adiponectin might increase LPL gene expression via AMP kinase activation in skeletal muscle. Based on these results, Qiao et al. proposed that adiponectin reduces plasma triglyceride levels by increasing triglyceride-rich lipoprotein catabolism in the skeletal muscle.
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