Affiliations: Department of Physical Therapy, University of
Kentucky, Lexington, KY, USA | Department of Psychology, University of Kentucky,
Lexington, KY, USA | Sanders-Brown Center on Aging, University
of Kentucky, Lexington, KY, USA | Department of Anatomy and Neurobiology, University of
Kentucky, Lexington, KY, USA
Abstract: Previous studies have suggested that brain-derived neurotrophic
factor (BDNF) is involved in memory and learning, and may be neuroprotective
following various brain insults. Exercise has been found to increase BDNF mRNA
levels in various brain regions, including specific subpopulations of
hippocampal neurons. In the present study, we were interested in whether
following traumatic brain injury, exercise could increase BDNF mRNA expression,
attenuate neuropathology, and improve cognitive and neuromoter performance. We
subjected adult male Sprague-Dawley rats to a fluid percussion brain injury,
followed by either 18 days of treadmill exercise or handling. Spatial memory
was evaluated in a Morris Water Maze (MWM) and motor function was evaluated
with a battery of neuromotor tests. Neuropathology was evaluated by measuring
the cortical lesion volume and the extent of neuronal loss in the hipocampus.
Expression of BDNF mRNA in the hippocampus was assessed with in situ
hybridization and densitometry. Hybridization signal for BDNF mRNA was
significantly increased bilaterally in the exercise group in hippocampal
regions CA1 and CA3 (p<0.05), but not in the granule cell layer of the
dentate gyrus. No significant differences were observed between the groups
in neuropathology, spatial memory, or motor performance. This study suggests
that after traumatic brain injury, exercise elevates BDNF mRNA in specific
regions of the hippocampus.
