The unfixed light pattern contributes to depressive-like behaviors in male mice

Qianyi Liu; Qinghe Meng; Yuecheng Ding; Jianjun Jiang; Chenping Kang; Lilan Yuan; Wanqian Guo; Zhe Zhao; Yue Yuan; Xuetao Wei; Weidong Hao

doi:10.1016/j.chemosphere.2023.139680

The unfixed light pattern contributes to depressive-like behaviors in male mice

Chemosphere. 2023 Oct:339:139680. doi: 10.1016/j.chemosphere.2023.139680. Epub 2023 Jul 29.

Authors

Affiliations

¹ Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China.
² Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China. Electronic address: qinghemeng0531@foxmail.com.
³ Department of Toxicology, School of Public Health, Peking University, Beijing, 100191, PR China; Beijing Key Laboratory of Toxicological Research and Risk Assessment for Food Safety, Beijing, 100191, PR China. Electronic address: whao@bjmu.edu.cn.

PMID: 37524266
DOI: 10.1016/j.chemosphere.2023.139680

Abstract

Light pollution is now associated with an increased incidence of mental disorders in humans, and the unfixed light pattern (ULP) is a common light pollution that occurs in such as rotating shift work. However, how much contribution the ULP has to depression and its potential mechanism are yet unknown. Our study aimed to investigate the effect of the ULP on depressive-like behaviors in mice and to explore the links to the circadian-orexinergic system. Male C57BL/6 J mice were exposed to the ULP by subjecting them to an alternating light pattern every 6 days for 54 days. The tail suspension test (TST) and forced swimming test (FST) were conducted to assess depressive-like behaviors. The rhythm of locomotor activity and the circadian expression of cFOS in the suprachiasmatic nucleus (SCN), clock genes in the liver, and corticosterone (CORT) in serum were detected to observe changes in the circadian system. The circadian expression of orexin-A (OX-A) in the lateral hypothalamus area (LHA) and dorsal raphe nucleus (DRN) and serotonin (5-HT) in the DRN were measured to determine alterations in the orexinergic system. The results showed that mice exposed to the ULP exhibited increased immobility time in the TST and FST. The ULP significantly disrupted the circadian rhythm of locomotor activity, clock genes in the liver, and CORT in the serum. Importantly, when exposed to the ULP, cFOS expression in the SCN showed decreased amplitude. Its projection area, the LHA, had a lower mesor of OX-A expression. OX-A projection to the DRN and 5-HT expression in the DRN were reduced in mesor. Our research suggests that the ULP contributes to depressive-like behaviors in mice, which might be related to the reduced amplitude of circadian oscillation in the SCN and hypoactivity of the orexinergic system. These findings may provide novel insights into rotating shift work-related depression.

Keywords: Circadian disruptions; Depression; Light pollution; Orexin A; Rotating shift work; Suprachiasmatic nucleus.

MeSH terms

Animals
Circadian Rhythm
Dorsal Raphe Nucleus* / metabolism
Humans
Light
Male
Mice
Mice, Inbred C57BL
Orexins
Serotonin* / metabolism

Substances

Serotonin
Orexins