Dim light at night increases depressive-like responses in male C3H/HeNHsd mice

Jan 8, 2013Behavioural brain research

Dim light at night increases depression-like behavior in male C3H/HeNHsd mice

AI simplified

Circadian Biology on OpenScience ↗PubMed ↗DOI ↗

Abstract

Mice exposed to nightly dim light at night (5 lux) show increased depressive-like behaviors after four weeks.

Depressive-like responses were assessed using sucrose anhedonia and forced swim tests.
Mice in dim light at night did not show differences in hippocampus-dependent learning and memory compared to those in dark conditions.
Gene expression of pro-inflammatory cytokines TNFα and IL1β remained unchanged between the two groups.
A significant reduction in BDNF expression was observed in the hippocampus of mice exposed to dim light at night.
These findings suggest that low levels of light exposure at night could influence mood in mice.

AI simplified

Daily patterns of light exposure have become increasingly variable since the widespread adoption of electrical lighting during the 20th century. Seasonal fluctuations in light exposure, shift-work, and transmeridian travel are all associated with alterations in mood. These studies implicate fluctuations in environmental lighting in the development of depressive disorders. Here we argue that exposure to light at night (LAN) may be causally linked to depression. Male C3H/HeNHsd mice, which produce nocturnal melatonin, were housed in either a standard light/dark (LD) cycle or exposed to nightly dim (5 lux) LAN (dLAN). After four weeks in lighting conditions mice underwent behavioral testing and hippocampal tissue was collected at the termination of the study for qPCR. Here were report that mice exposed to dLAN increase depressive-like responses in both a sucrose anhedonia and forced swim test. In contrast to findings in diurnal grass rats, dLAN mice perform comparably to mice housed under dark nights in a hippocampus-dependent learning and memory task. TNFα and IL1β gene expression do not differ between groups, demonstrating that changes in these pro-inflammatory cytokines do not mediate dLAN induced depressive-like responses in mice. BDNF expression is reduced in the hippocampus of mice exposed to dLAN. These results indicate that low levels of LAN can alter mood in mice. This study along with previous work implicates LAN as a potential factor contributing to depression. Further understanding of the mechanisms through which LAN contributes to changes in mood is important for characterizing and treating depressive disorders.

Full Text

Full text is available at the source.

View full text (XML) ↗View full text ↗

Dim light at night increases depressive-like responses in male C3H/HeNHsd mice

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief

Abstract

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the circadian biology brief