title: Chronic exposure to dim light at night suppresses immune responses in Siberian hamsters.
abstract: Species have been adapted to specific niches optimizing survival and reproduction; however, urbanization by humans has dramatically altered natural habitats. Artificial light at night (LAN), termed 'light pollution', is an often overlooked, yet increasing disruptor of habitats, which perturbs physiological processes that rely on precise light information. For example, LAN alters the timing of reproduction and activity in some species, which decreases the odds of successful breeding and increases the threat of predation for these individuals, leading to reduced fitness. LAN also suppresses immune function, an important proxy for survival. To investigate the impact of LAN in a species naive to light pollution in its native habitat, immune function was examined in Siberian hamsters derived from wild-caught stock. After four weeks exposure to dim LAN, immune responses to three different challenges were assessed: (i) delayed-type hypersensitivity (DTH), (ii) lipopolysaccharide-induced fever, and (iii) bactericide activity of blood. LAN suppressed DTH response and reduced bactericide activity of blood after lipopolysaccharide treatment, in addition to altering daily patterns of locomotor activity, suggesting that human encroachment on habitats via night-time lighting may inadvertently compromise immune function and ultimately fitness.
authors.affiliation: Department of Neuroscience, The Ohio State University Medical Center, Columbus, OH 43210, USA. tracy.bedrosian@osumc.edu
authors.forename: Tracy A
authors.initials: TA
authors.lastname: Bedrosian
authors.forename: Laura K
authors.initials: LK
authors.lastname: Fonken
authors.forename: James C
authors.initials: JC
authors.lastname: Walton
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Nelson
mesh_terms: D000818:Animals; D001770:Blood Bactericidal Activity / Q000276:immunology; D002940:Circadian Rhythm; D006224:Cricetinae; D005334:Fever / Q000276:immunology; D006968:Hypersensitivity, Delayed / Q000276:immunology; D007109:Immunity; D008027:Light / Q000009:adverse effects*; D008070:Lipopolysaccharides; D008124:Locomotion; D017111:Phodopus / Q000276:immunology*
chemical_list: D008070:Lipopolysaccharides