title: Late exercise reduces neuroinflammation and cognitive dysfunction after traumatic brain injury.
abstract: Delayed secondary biochemical and cellular changes after traumatic brain injury continue for months to years, and are associated with chronic neuroinflammation and progressive neurodegeneration. Physical activity can reduce inflammation and facilitate recovery after brain injury. Here, we investigated the time-dependent effects, and underlying mechanisms of post-traumatic exercise initiation on outcome after moderate traumatic brain injury using a well-characterized mouse controlled cortical impact model. Late exercise initiation beginning at 5weeks after trauma, but not early initiation of exercise at 1week, significantly reduced working and retention memory impairment at 3months, and decreased lesion volume compared to non-exercise injury controls. Cognitive recovery was associated with attenuation of classical inflammatory pathways, activation of alternative inflammatory responses and enhancement of neurogenesis. In contrast, early initiation of exercise failed to alter behavioral recovery or lesion size, while increasing the neurotoxic pro-inflammatory responses. These data underscore the critical importance of timing of exercise initiation after trauma and its relation to neuroinflammation, and challenge the widely held view that effective neuroprotection requires early intervention.
authors: Center for Shock, Trauma and Anesthesiology Research (STAR) and Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors: Chun-Shu
authors: CS
authors: Piao
authors: Bogdan A
authors: BA
authors: Stoica
authors: Junfang
authors: J
authors: Wu
authors: Boris
authors: B
authors: Sabirzhanov
authors: Zaorui
authors: Z
authors: Zhao
authors: Rainier
authors: R
authors: Cabatbat
authors: David J
authors: DJ
authors: Loane
authors: Alan I
authors: AI
authors: Faden
mesh_terms: D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000473:pathology; D001930:Brain Injuries / Q000473:pathology* / Q000534:rehabilitation*; D003072:Cognition Disorders / Q000209:etiology / Q000473:pathology / Q000534:rehabilitation*; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D007249:Inflammation / Q000473:pathology / Q000517:prevention & control; D051379:Mice; D010805:Physical Conditioning, Animal / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D020127:Recovery of Function / Q000502:physiology*