Browsing by Author "Duffield, Giles E."

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    Dissociation between diurnal cycles in locomotor activity, feeding behavior and hepatic PERIOD2 expression in chronic alcohol-fed mice
    (Elsevier, 2015-06) Zhou, Peng; Werner, John H.; Lee, Donghoon; Sheppard, Aaron D.; Liangpunsakul, Suthat; Duffield, Giles E.; Department of Medicine, IU School of Medicine
    Chronic alcohol consumption contributes to fatty liver disease. Our studies revealed that the hepatic circadian clock is disturbed in alcohol-induced hepatic steatosis, and effects of chronic alcohol administration upon the clock itself may contribute to steatosis. We extended these findings to explore the effects of chronic alcohol treatment on daily feeding and locomotor activity patterns. Mice were chronically pair-fed ad libitum for 4 weeks using the Lieber-DeCarli liquid diet, with calorie-controlled liquid and standard chow diets as control groups. Locomotor activity, feeding activity, and real-time bioluminescence recording of PERIOD2::LUCIFERASE expression in tissue explants were measured. Mice on liquid control and chow diets exhibited normal profiles of locomotor activity, with a ratio of 22:78% day/night activity and a peak during early night. This pattern was dramatically altered in alcohol-fed mice, marked by a 49:51% ratio and the absence of a distinct peak. While chow-diet fed mice had a normal 24:76% ratio of feeding activity, with a peak in the early night, this pattern was dramatically altered in both liquid-diet groups: mice had a 43:57% ratio, and an absence of a distinct peak. Temporal differences were also observed between the two liquid-diet groups during late day. Cosinor analysis revealed a ∼4-h and ∼6-h shift in the alcohol-fed group feeding and locomotor activity rhythms, respectively. Analysis of hepatic PER2 expression revealed that the molecular clock in alcohol-fed and control liquid-diet mice was shifted by ∼11 h and ∼6 h, respectively. No differences were observed in suprachiasmatic nucleus explants, suggesting that changes in circadian phase in the liver were generated independently from the central clock. These results suggest that chronic alcohol consumption and a liquid diet can differentially modulate the daily rhythmicity of locomotor and feeding behaviors, aspects that might contribute to disturbances in the circadian timing system and development of hepatic steatosis.
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    High fat diet rescues disturbances to metabolic homeostasis and survival in the Id2 null mouse in a sex-specific manner
    (Elsevier B.V., 2014-08-29) Zhou, Peng; Hummel, Alyssa D.; Pywell, Cameron M.; Dong, X. Charlie; Duffield, Giles E.; Department of Biochemistry & Molecular Biology, IU School of Medicine
    Inhibitor of DNA binding 2 (ID2) is a helix-loop-helix transcriptional repressor rhythmically expressed in many adult tissues. Our previous studies have demonstrated that Id2 null mice have altered expression of circadian genes involved in lipid metabolism, altered circadian feeding behavior, and sex-specific enhancement of insulin sensitivity and elevated glucose uptake in skeletal muscle and brown adipose tissue. Here we further characterized the Id2−/− mouse metabolic phenotype in a sex-specific context and under low and high fat diets, and examined metabolic and endocrine parameters associated with lipid and glucose metabolism. Under the low-fat diet Id2−/− mice showed decreased weight gain, reduced gonadal fat mass, and a lower survival rate. Under the high-fat diet, body weight and gonadal fat gain of Id2−/− male mice was comparable to control mice and survival rate improved markedly. Furthermore, the high-fat diet treated Id2−/− male mice lost the enhanced glucose tolerance feature observed in the other Id2−/− groups, and there was a sex-specific difference in white adipose tissue storage of Id2−/− mice. Additionally, a distinct pattern of hepatic lipid accumulation was observed in Id2−/− males: low lipids on the low-fat diet and steatosis on the high-fat diet. In summary, these data provides valuable insights into the impact of Id2 deficiency on metabolic homeostasis of mice in a sex-specific manner.