title: Experimental 'jet lag' inhibits adult neurogenesis and produces long-term cognitive deficits in female hamsters.
abstract: BACKGROUND
  Circadian disruptions through frequent transmeridian travel, rotating shift work, and poor sleep hygiene are associated with an array of physical and mental health maladies, including marked deficits in human cognitive function. Despite anecdotal and correlational reports suggesting a negative impact of circadian disruptions on brain function, this possibility has not been experimentally examined.
  
  
  RESULTS
  In the present study, we investigated whether experimental 'jet lag' (i.e., phase advances of the light:dark cycle) negatively impacts learning and memory and whether any deficits observed are associated with reductions in hippocampal cell proliferation and neurogenesis. Because insults to circadian timing alter circulating glucocorticoid and sex steroid concentrations, both of which influence neurogenesis and learning/memory, we assessed the contribution of these endocrine factors to any observed alterations. Circadian disruption resulted in pronounced deficits in learning and memory paralleled by marked reductions in hippocampal cell proliferation and neurogenesis. Significantly, deficits in hippocampal-dependent learning and memory were not only seen during the period of the circadian disruption, but also persisted well after the cessation of jet lag, suggesting long-lasting negative consequences on brain function.
  
  
  CONCLUSIONS
  Together, these findings support the view that circadian disruptions suppress hippocampal neurogenesis via a glucocorticoid-independent mechanism, imposing pronounced and persistent impairments on learning and memory.
authors.affiliation: Department of Psychology, University of California, Berkeley, California, United States of America.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Gibson
authors.forename: Connie
authors.initials: C
authors.lastname: Wang
authors.forename: Stephanie
authors.initials: S
authors.lastname: Tjho
authors.forename: Neera
authors.initials: N
authors.lastname: Khattar
authors.forename: Lance J
authors.initials: LJ
authors.lastname: Kriegsfeld
mesh_terms: D000818:Animals; D001921:Brain / Q000503:physiopathology; D049109:Cell Proliferation; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology*; D006224:Cricetinae; D004195:Disease Models, Animal; D005260:Female; D005938:Glucocorticoids / Q000378:metabolism; D006624:Hippocampus / Q000473:pathology; D007030:Hypothalamo-Hypophyseal System; D020179:Jet Lag Syndrome / Q000503:physiopathology*; D008568:Memory; D009474:Neurons / Q000473:pathology; D012890:Sleep
chemical_list: D005938:Glucocorticoids