Effects of long-term noise exposure during sleep on liver circadian clock and lipid metabolism

Abstract

BackgroundLong-term exposure to noise during sleep may has adverse effects on metabolic system, and liver lipid metabolism is closely related to circadian clock genes. ObjectiveTo investigate the effects of long-term noise exposure during sleep on liver circadian clock and lipid metabolism in mice and its related mechanism. MethodsTwenty C57BL/6J male mice were randomly divided into two groups: a noise exposure group and a control group with 10 mice in each group. The mice in the noise exposure group were exposed to white noise at 90 dB sound pressure level (SPL) for 30 consecutive days, 8 h a day, from 9:00 to 17:00. The mice in the control group were exposed to background noise ≤40 dB SPL. After noise exposure, the animals were neutralized at 14:00 (ZT6) and 2:00 (ZT18), 5 animals at each time spot, and the liver tissues were collected. Total cholesterol and triglyceride in liver were determined by cholesterol oxidase method and glycerol phosphate oxidase method respectively. The expressions of circadian clock genes (Clock, Bmal1, Rev-erbα, and Rev-erbβ) and lipid metabolism genes (Srebp1c, Hmgcr, Fasn, Lxrα, Acc1, and Chrebp) in liver were detected by quantitative real-time PCR. ResultsCompared with the control group, the content of total cholesterol in liver in the noise exposure group increased by 48% (P0.05). ConclusionLong-term noise exposure during sleep can cause circadian clock and lipid metabolism disorders in mice. Among them, suppression of key circadian clock genes may be associated with Rev-erbα-mediated upregulation of the nuclear receptors Srebp1c and Chrebp for lipid synthesis and deposition in the liver, resulting in lipid metabolism disorder.

Keywords

• sleep noise
• circadian clock
• lipid metabolism
• liver