Sub-concussive brain injury in the Long-Evans rat induces acute neuroinflammation in the absence of behavioral impairments

Behav Brain Res. 2012 Apr 1;229(1):145-52. doi: 10.1016/j.bbr.2011.12.015. Epub 2011 Dec 19.


Sub-concussive brain injuries may result in neurophysiological changes, cumulative effects, and neurodegeneration. The current study investigated the effects of a mild lateral fluid percussion injury (0.50-0.99 atm) on rat behavior and neuropathology to address the need to better understand sub-concussive brain injury. Male Long-Evans rats received either a single mild lateral fluid percussion injury or a sham-injury, followed by either a short (24 h) or long (4 weeks) recovery period. After recovery, rats underwent extensive behavioral testing consisting of tasks for rodent cognition, anxiety- and depression-like behaviors, social behavior, and sensorimotor function. At the completion of behavioral testing rats were sacrificed and brains were examined immunohistochemically with markers for neuroinflammation and axonal injury. No significant group differences were found on behavioral and axonal injury measures. However, rats given one mild fluid percussion injury displayed an acute neuroinflammatory response, consisting of increased microglia/macrophages and reactive astrogliosis, at 4 days post-injury. Neuroinflammation is a mechanism with the potential to contribute to the cumulative and neurodegenerative effects of repeated sub-concussive injuries. The current findings are consistent with findings in humans experiencing a sub-concussive blow, and provide support for the use of mild lateral fluid percussion injury in the rat as a model of sub-concussive brain injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid beta-Protein Precursor / metabolism
  • Analysis of Variance
  • Animals
  • Antigens, CD / metabolism
  • Antigens, Differentiation, Myelomonocytic / metabolism
  • Anxiety / etiology
  • Behavior, Animal / physiology*
  • Brain / metabolism
  • Brain / pathology
  • Brain Concussion / complications*
  • Cell Count / methods
  • Disease Models, Animal
  • Encephalitis / physiopathology*
  • Glial Fibrillary Acidic Protein / metabolism
  • Locomotion / physiology
  • Male
  • Maze Learning / physiology
  • Rats
  • Rats, Long-Evans
  • Recovery of Function / physiology*
  • Social Behavior
  • Time Factors


  • Amyloid beta-Protein Precursor
  • Antigens, CD
  • Antigens, Differentiation, Myelomonocytic
  • CD68 antigen, human
  • Glial Fibrillary Acidic Protein