Chronic blue light exposure induced spatial anxiety in an adolescent mouse model: Per2 upregulation and altered brain resting-state functional activity

Background

Blue light (BL) is the primary component of light emitted from 3C devices. The use of 3C (computers, consumer electronics, and communication) devices has been increasing among all age groups. How social interaction and spatial cognition are affected in adolescents after long-term 3C device usage at night remains unclear.

Methods

Five-week-old mice were exposed to BL. Subsequently, these mice were subjected to social behavior tests, functional magnetic resonance imaging, and histopathologic analyses.

Results

BL exposure increased spatial anxiety but did not affect sociability, social novelty, or motor coordination. Also, BL exposure altered brain connectivity in the hippocampus (Hip), thalamus, and striatum, and it reduced brain activity in the retrosplenial cortex and dorsal part of the Hip. Spatial anxiety was associated with brain alterations. Although BL exposure reduced the size of retinal oligodendrocytes and increased the expression of the Period 2 circadian protein, it did not result in brain inflammation, at least not in the Hip.

Conclusion

Our findings highlight that long-term BL exposure in adolescents induces spatial anxiety. The underlying mechanisms include changes in brain activity and connectivity and the disruption of the circadian rhythm.