genes [60]. Circadian oscillators play an indispensable role in the coordination of physiological processes with the cyclic changes in the physical environment. A significant number of recent clinical and molecular studies suggest that circadian biology may play an important role in the regulation of adipose and other metabolic tissue functions and circadian dysfunction may be involved in the pathogenesis of obesity, type 2 diabetes, and the metabolic syndrome [61]. In mammals, the “master clock” driving circadian rhythm is located in the hypothalamic suprachiasmatic nucleus (SCN). The brain area contains neurons whose firing rates vary over an approximately 24-hour period and, in turn, coordinates the oscillation of “slave clocks” in other areas throughout the brain and periphery [62]. The molecular mechanisms underlying these oscillations were firstly described in Drosophila, but homologous genes have been identified across diverse species. The genes encoding the core clock mechanisms include circadian locomotor output cycles kaput (Clock), brain and muscle-Arnt-like 1 (Bmal1), Period-1 (Per1), Period-2 (Per2), Period-3 (Per3), Cryptochrome-1 (Cry1), and Cryptochrome2 (Cry2) [62].
