Prolonged Light Exposure Induces Circadian Impairment in Aquaporin-4-Knockout Mice. Issue 2 (April 2023)

• Record Type: Journal Article
• Authors: Murakami, Atsumi; Tsuji, Kouki; Isoda, Minako; Matsuo, Masahiro; Abe, Yoichiro; Yasui, Masato; Okamura, Hitoshi; Tominaga, Keiko
• Is Part Of: Journal of biological rhythms. Volume 38:Issue 2(2023)
• Page Start: 208
• Page End: 214
• Publication Date: 2023-04
• Subjects: circadian rhythms -- suprachiasmatic nucleus -- AQP4 -- constant light -- circadian rhythm impairment and reappearance -- AQP4-knockout mice; Biological rhythms -- Periodicals; Circadian rhythms -- Periodicals; 571.77
• DOI: 10.1177/07487304221146242
• Languages: English
• ISSNs: 0748-7304

Abstract

Astrocytes are densely present in the suprachiasmatic nucleus (SCN), which is the master circadian oscillator in mammals, and are presumed to play a key role in circadian oscillation. However, specific astrocytic molecules that regulate the circadian clock are not yet well understood. In our study, we found that the water channel aquaporin-4 (AQP4) was abundantly expressed in SCN astrocytes, and we further examined its circadian role using AQP4-knockout mice. There was no prominent difference in circadian behavioral rhythms between Aqp4 -/- and Aqp4 +/+ mice subjected to light-dark cycles and constant dark conditions. However, exposure to constant light induced a greater decrease in the Aqp4 -/- mice rhythmicity. Although the damped rhythm in long-term constant light recovered after transfer to constant dark conditions in both genotypes, the period until the reappearance of original rhythmicity was severely prolonged in Aqp4 -/- mice. In conclusion, AQP4 absence exacerbates the prolonged light-induced impairment of circadian oscillations and delays their recovery to normal rhythmicity.