Effect and mechanism of circadian rhythm disruption caused by light pollution on bone microarchitecture in mice
WANG Qian
ZHANG Mian
KOU Wei
LIU Huanlong
LI Mengzhi
SUN Jun
QIU Shenqiang
Abstract：Objective To investigate the effect of circadian rhythm disruption caused by light pollution on bone mi-croarchitecture in mice and its underlying mechanism of action.Methods Twelve mice were divided into four groups(n=3 per group)using a random number table:the normal circadian rhythm group,the model group,the melatonin interven-tion group,and the rhythm recovery group.Mice in the normal circadian rhythm group were maintained under a standard 12-hour light-dark cycle(12 h light:12 h darkness)throughout the experimental period.Mice in the remaining groups were exposed to an extended photoperiod(15 h light:9 h darkness)to simulate light pollution and induce circadian rhythm dis-ruption.Mice in the melatonin intervention group received daily oral administration of melatonin at a dose of 10 mg/(kg·d)concomitantly with the modeling phase.Mice in the rhythm recovery group were returned to the standard 12-hour light-dark cycle after 8 weeks of prolonged light exposure and were then maintained under these conditions for an additional 8 weeks.At the conclusion of the 16-week study,femoral specimens were collected.Bone microarchitectural parameters,including bone volume fraction,trabecular thickness,and trabecular number,were assessed using high-resolution micro-computed tomography.Osteoclast density was calculated via Tartrate-resistant acid phosphatase(TRAP)staining.Pearson correla-tion analysis was performed to assess the relationships between osteoclast density and bone microarchitecture parame-ters.Results Compared with the normal rhythm group,the model group exhibited significantly lower bone volume frac-tion(BV/TV),reduced trabecular thickness(Tb.Th),decreased trabecular number(Tb.N),and elevated osteoclast den-sity(all P<0.05).No statistically significant differences were observed in BV/TV,Tb.Th,Tb.N,or osteoclast density be-tween the model group and the melatonin intervention group(all P>0.05).In contrast,the rhythm recovery group showed significantly higher BV/TV,greater Tb.Th,increased Tb.N,and lower osteoclast density(all P<0.05).Furthermore,os-teoclast density was negatively correlated with BV/TV,Tb.N,and Tb.Th(r=-0.669,-0.826,and-0.857,respective-ly;all P<0.05).Conclusions Long-term exposure to light pollution impairs bone microarchitecture in mice,potentially mediated by aberrantly increased osteoclast activity.Although exogenous melatonin does not effectively mitigate this patho-logical process,optimizing ambient light conditions may represent a viable strategy for preserving skeletal health.
Keywords：light pollutioncircadian rhythm disturbancebone microarchitectureosteoclastsmelatoninmice
Publication Date：2026-02-25
Online Publishing Date：2026-03-19(First online date of this platform, not the publication date of the document)
Pages：4( 53-55,64 )