Melatonin promotes adipogenesis and mitochondrial biogenesis in 3T3‐L1 preadipocytes

Melatonin is synthesized in the pineal gland, but elicits a wide range of physiological responses in peripheral target tissues. Recent advances suggest that melatonin controls adiposity, resulting in changes in body weight. The aim of this study was to investigate the effect of melatonin on adipogenesis and mitochondrial biogenesis in 3T3‐L1 mouse embryo fibroblasts. Melatonin significantly increased the expression of peroxisome proliferator‐activated receptor‐γ (PPAR‐γ), a master regulator of adipogenesis, and promoted differentiation into adipocytes. Melatonin‐treated cells also formed smaller lipid droplets and abundantly expressed several molecules associated with lipolysis, including adipose triglyceride lipase, perilipin, and comparative gene identification‐58. Moreover, the hormone promoted biogenesis of mitochondria, as indicated by fluorescent staining, elevated the citrate synthase activity, and upregulated the expression of PPAR‐γ coactivator 1α, nuclear respiratory factor‐1, and transcription factor A. The expression of uncoupling protein 1 was also observable both at mRNA and at protein level in melatonin‐treated cells. Finally, adiponectin secretion and the expression of adiponectin receptors were enhanced. These results suggest that melatonin promotes adipogenesis, lipolysis, mitochondrial biogenesis, and adiponectin secretion. Thus, melatonin has potential as an anti‐obesity agent that may reverse obesity‐related disorders.