title: Environmental Circadian Disruption Worsens Neurologic Impairment and Inhibits Hippocampal Neurogenesis in Adult Rats After Traumatic Brain Injury.
abstract: Circadian rhythms modulate many physiologic processes and behaviors. Therefore, their disruption causes a variety of potential adverse effects in humans and animals. Circadian disruption induced by constant light exposure has been discovered to produce pathophysiologic consequences after brain injury. However, the underlying mechanisms that lead to more severe impairment and disruption of neurophysiologic processes are not well understood. Here, we evaluated the effect of constant light exposure on the neurobehavioral impairment and survival of neurons in rats after traumatic brain injury (TBI). Sixty adult male Sprague-Dawley rats were subjected to a weight-drop model of TBI and then exposed to either a standard 12-/12-h light/dark cycle or a constant 24-h light/light cycle for 14 days. Our results showed that 14 days of constant light exposure after TBI significantly worsened the sensorimotor and cognitive deficits, which were associated with decreased body weight, impaired water and food intake, increased cortical lesion volume, and decreased neuronal survival. Furthermore, environmental circadian disruption inhibited cell proliferation and newborn cell survival and decreased immature cell production in rats subjected to the TBI model. We conclude that circadian disruption induced by constant light exposure worsens histologic and neurobehavioral impairment and inhibits neurogenesis in adult TBI rats. Our novel findings suggest that light exposure should be decreased and circadian rhythm reestablished in hospitalized TBI patients and that drugs and strategies that maintain circadian rhythm would offer a novel therapeutic option.
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.|Henan Province Red Cross Blood Center, Zhengzhou, Henan, 450014, People's Republic of China.
authors.forename: Dongpeng
authors.initials: D
authors.lastname: Li
authors.affiliation: School of Life Sciences, Zhengzhou University, Zhengzhou, 450001, People's Republic of China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Ma
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.
authors.forename: Dewei
authors.initials: D
authors.lastname: Guo
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.|Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, 21205, USA.
authors.forename: Tian
authors.initials: T
authors.lastname: Cheng
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Tian
authors.affiliation: Henan Province Red Cross Blood Center, Zhengzhou, Henan, 450014, People's Republic of China.
authors.forename: Jianbin
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Life Sciences, Zhengzhou University, Zhengzhou, 450001, People's Republic of China. guanfangxia@126.com.
authors.forename: Fangxia
authors.initials: F
authors.lastname: Guan
authors.affiliation: Department of Neurosurgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China. yangbo96@126.com.
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD, 21205, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D000375:Aging; D000818:Animals; D000070642:Brain Injuries, Traumatic / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology*; D004777:Environment; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000473:pathology; D017207:Rats, Sprague-Dawley
keywords: Circadian rhythms; Constant light; Hippocampus; Neurogenesis; Traumatic brain injury