Adding weight to biological clock-driven obesity
Roughly 24 hour circadian rhythms drive and coordinate many biochemical, physiological and behavioural processes. Significantly, regulation of lipid synthesis and fatty acid oxidation are controlled by genes modulated by biological clocks. The OBESITY AND LIGHT (Bringing obesity to light - do obesogenic chemicals affect lipid metabolism through changes in circadian rhythm?) project has used the zebrafish to investigate the effects of clock changes on formation and accumulation of lipids in the body. OBESITY AND LIGHT researchers showed that under continuous light rather than shifted light-dark cycles, the fish made even more fat cells than with a high-calorie diet. Furthermore, adipogenesis is regulated in part by peroxisomal proliferator activated receptors (Ppars) isoforms and one of these has several binding sites for the clock gene Rev-erbα. This indicates that adipocyte formation is linked to light-driven clock genes. Moreover, the project team demonstrated that exposure of zebrafish larvae to endocrine disruptors that disturbed circadian clock activity promoted fat cell accumulation. Also, chemicals known to change clock activity increased lipid accumulation. Project data clearly demonstrated the two-way link between circadian clocks and fat metabolism. As many physiological processes are reliant on input from biological time cycles, this has wide implications for health due to the action of some environmental compounds. Treatment of cancer, sleeping disorders and metabolic diseases such as obesity may all benefit from this research.
Keywords
Biological clock, obesity, circadian rhythm, lipid, endocrine disruptor