抄録
Major components of energy homeostasis are subjected to circadian regulation that synchronizes energy intake and expenditure. Recently, relationship of circadian clock and lipid metabolism is highlighted. The CLOCK transcription factor is a key component of the molecular circadian clock. Adipocytes play essential metabolic roles not only serving as energy reserves but also secreting hormones and cytokines that regulate metabolic activities. Clock mutant mice were fed with high fat diet for 13 weeks, and lipid metabolism was investigated. Both wild type and Clock mutant mice gained body weight. But, in Clock mutant mice, increases of body weight and of adipocyte tissue were significantly attenuated. In Clock mutant mice, total cholesterol of plasma and liver, and triglyceride of liver were significantly lowered. Again, we examined clock controlled gene mRNA in the adipocyte by real-time RT-PCR. Plasminogen activator inhibitor type 1 (Pai-1) which is related to cardiac infarction was significantly down-regulated in Clock mutant mice. As a summary, we showed that Clock mutant mice may have abnormal lipid metabolism. [J Physiol Sci. 2006;56 Suppl:S97]
