A Growth Hormone-Releasing Peptide Promotes Mitochondrial Biogenesis and a Fat Burning-Like Phenotype through Scavenger Receptor CD36 in White Adipocytes

Whereas the uptake of oxidized lipoproteins by scavenger receptor CD36 in macrophages has been associated with foam cell formation and atherogenesis, little is known about the role of CD36 in regulating lipid metabolism in adipocytes. Here we report that treatment of 3T3-L1 adipocytes with hexarelin, a GH-releasing peptide that interacts with CD36, resulted in a depletion of intracellular lipid content with no significant change in CD36 expression. Microarray analysis revealed an increased pattern in several genes involved in fatty acid mobilization toward the mitochondrial oxidative phosphorylation process in response to hexarelin. Interestingly, many of these up-regulated genes are known targets of peroxisomal proliferator-activated receptor (PPAR)-γ, such as FATP, CPT-1, and F1-ATPase, suggesting that adipocyte response to hexarelin may involve PPARγ activation. Expression studies also indicate an increase in thermogenic markers PPARγ coactivator 1α and uncoupling protein-1, which are normally expresse...