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Julie Pendergast

Education

Research Assistant Professor of Medicine, Vanderbilt University, Div of Diabetes,
Endocrinology, and Metabolism, 2012-2015
Postdoctoral Fellow, Vanderbilt University, Dept of Biological Sciences, 2007-2012
Ph.D., Neuroscience, University of Miami, 2007
M.S., Biology, University of Illinois Urbana-Champaign, 2001
B.S., Cell and Structural Biology, University of Illinois Urbana-Champaign, 1999

Circadian Rhythms and Metabolism

My primary research interest is the study of mammalian circadian rhythms. These are 24-h, daily rhythms that are present at every level of biology from gene expression to complex behavior.  The integrity of circadian rhythms is important for good health. For example, shift work, which chronically disrupts circadian rhythms, is associated with increased risk of obesity, cancer, suppression of the immune system and other health problems. In my research I use rodent models to study circadian rhythms and how disrupting these rhythms leads to poor health. Specifically, I am interested in the interplay between the circadian and metabolic systems, with a focus on how circadian disruption contributes to obesity.

The mammalian circadian system is a hierarchial network of oscillators: the master pacemaker in the suprachiasmatic nucleus (SCN) of the hypothalamus receives information about the light-dark cycle and coordinates the timing of clocks located throughout the brain and body. This organization of circadian clocks results in precise temporal control of behavior and physiology. We found that eating a high-fat diet disrupts this circadian organization and alters daily rhythms of eating behavior and locomotor activity. The overarching goal of my research is to elucidate how the circadian and metabolic systems interact to control physiology and behavior. To this end, ongoing research in the lab investigates (i) the mechanisms whereby high-fat diet disrupts circadian organization; (ii) the metabolic consequences of circadian disorganization; and (iii) how female obesity and circadian rhythms differ from males.

In the lab we measure circadian behavior (eating and activity rhythms) and bioluminescence rhythms in brain and peripheral tissues cultured from transgenic mice. Additionally, we analyze circadian rhythms of whole body metabolism, plasma hormones, and glucose metabolism. Research in the lab spans multiple disciplines including chronobiology, neuroscience, behavior, physiology, and metabolism.