A study on effect of altered circadian rhythm in the development of obesity.

Authors:Nilesh N. Kate , M. Chandrasekhar , Ambareesha Kondam , E. Kayalvizhi , M.Suresh, U Kavitha
Int J Biol Med Res. 2012; 3(2): 1595 – 1601  |  PDF File

Abstract

Background: Most living things have a daily cycle that reflects the rising and setting of the sun. A variety of studies have demonstrated that retinal light exposure can increase alertness at night. The global increase in the prevalence of obesity and metabolic disorders coincides with the increase of exposure to light at night (LAN) and shift work. The circadian clock prepares individuals for predictable events such as food availability and sleep, and disruption of clock function causes circadian and metabolic disturbances. Aim: To determine whether a causal relationship exists between night time light exposure behavioral changes and obesity. Methods: In this experiment 18 Swiss–albino male mice were divided into three groups i.e. Continuous light exposure (CL), light at night (LAN), standard (LD) light/dark cycle (control) and the effect of altered circadian rhythm on development of obesity and behavioral changes is seen. The body mass was assessed at the end of eight weeks to find out whether there was any correlation between the three variants. Results: Mice housed in continuous light (CL) or LAN have significantly increased body mass and increased prevalence of day time eating and altered behavioral pattern than mice in a standard (LD) light/dark cycle. Conclusion: These results suggest that light at night disrupt the timing of food intake and other metabolic signals, leading to excess weight gain. Melatonin is vital to this process, mediating the seasonal photoperiodic information through the clock system. Disrupting the melatonin signal or increasing the duration of light leads to changes in metabolism and adiposity consistent with fat storage and insulin resistance. These data are relevant to the coincidence between increasing use of light at night and obesity in humans (night shift worker).