Shift workers’ constantly changing schedules make it tough for their biological clocks to keep accurate time. The results could make the negative effects of a high-fat diet even more pronounced, a new study suggests.
About 15 million Americans don’t have a typical nine-to-five workday, and many of them—nurses, firefighters, and flight attendants, among other professions—may see their schedule change drastically one week to the next…..
Shift work cycle-induced alterations of circadian rhythms potentiate the effects of high fat diet on inflammation and metabolism
Source: Sam-Moon Kim, Nichole Neuendorff, Robert C. Alaniz, Yuxiang Sun, Robert S. Chapkin, and David J. Earnest, Federation of American Societies for Experimental Biology (FASEB) Journal, Published Online: 5 Feb 2018
From the abstract:
Based on genetic models with mutation or deletion of core clock genes, circadian disruption has been implicated in the pathophysiology of metabolic disorders. Thus, we examined whether circadian desynchronization in response to shift work–type schedules is sufficient to compromise metabolic homeostasis and whether inflammatory mediators provide a key link in the mechanism by which alterations of circadian timekeeping contribute to diet-induced metabolic dysregulation. In high-fat diet (HFD)-fed mice, exposure to chronic shifts of the light–dark cycle (12 h advance every 5 d): 1) disrupts photoentrainment of circadian behavior and modulates the period of spleen and macrophage clock gene rhythms; 2) potentiates HFD-induced adipose tissue infiltration and activation of proinflammatory M1 macrophages; 3) amplifies macrophage proinflammatory cytokine expression in adipose tissue and bone marrow–derived macrophages; and 4) exacerbates diet-induced increases in body weight, insulin resistance, and glucose intolerance in the absence of changes in total daily food intake. Thus, complete disruption of circadian rhythmicity or clock gene function as transcription factors is not requisite to the link between circadian and metabolic phenotypes. These findings suggest that macrophage proinflammatory activation and inflammatory signaling are key processes in the physiologic cascade by which dysregulation of circadian rhythmicity exacerbates diet-induced systemic insulin resistance and glucose intolerance.