Lights at night mediate depression-like behavioral and molecular phenotypes in a glucocorticoid-dependent manner in...

Area of Science:

• Neuroscience
• Environmental Health
• Psychiatry

Background:

• Nocturnal light pollution (NLP) is increasingly recognized as a factor affecting mood disorders.
• Existing research suggests a link between light at night (LAN) exposure and depression-like phenotypes, but underlying mechanisms are not fully understood.

Purpose of the Study:

• To investigate the impact of nocturnal light exposure on depression-related brain regions.
• To examine the effects of LANs on brain-derived neurotrophic factor (BDNF), synaptic transmission, and plasticity.

Main Methods:

• Male Sprague-Dawley rats were exposed to white or blue light at night (LAN) for 5 or 21 days.
• Behavioral tests, enzyme-linked immunosorbent assays, and electrophysiological recordings were employed.
• Pharmacological interventions targeted glucocorticoid receptors to assess their role.

Main Results:

• LAN exposure induced depression-like behaviors in rats.
• Both white and blue LANs decreased BDNF levels in the medial prefrontal cortex (mPFC) and ventrolateral periaqueductal gray (vlPAG).
• LANs impaired synaptic transmission and plasticity in the mPFC and vlPAG, a process dependent on glucocorticoid receptor activation.

Conclusions:

• Nocturnal light exposure disrupts BDNF expression, synaptic function, and plasticity in key brain areas.
• These effects are mediated through a glucocorticoid-dependent pathway.
• Findings provide a mechanistic understanding of how light at night may contribute to depression.