Influence of Wheel Running and Environmental Complexity on Adult Hippocampal Neurogenesis in Rats Postnatally Exposed to Alcohol
Date
2015-05
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University of Delaware
Abstract
In humans, exposure to alcohol during prenatal development can lead to Fetal
Alcohol Spectrum Disorders, which cause a multitude of detriments to the central
nervous system that persist throughout the life of an individual. One brain region
particularly susceptible to alcohol exposure during the third trimester of pregnancy is the hippocampus, an area critical for learning, spatial memory and overall cognition. A potential mechanism by which developmental alcohol exposure may interfere with hippocampal structure and function is through the alteration of the propensity for adult
neurogenesis, which is the continuous generation of neurons in the adult brain.
Previous work in our lab has demonstrated that alcohol exposure impairs new cell
survival in the adult hippocampus, and then, differentially, that behavioral
interventions (voluntary exercise and environmental complexity) attenuate alcoholinduced deficits to adult neurogenesis. The current study seeks to investigate how immature neurons within the dentate gyrus respond to an insult of alcohol incurred during development, and how the beneficial interventions of wheel running and
environmental complexity affect the brain into adulthood. For these experiments,
animals were exposed to alcohol on postnatal days (PD) 4-9 (5.25 g/kg/day) and then housed in one of three different conditions from PD30-72: social housing (SH),
voluntary wheel running (WR/WR), and wheel running (12 days) followed by
9 environmental complexity (30 days; WR/EC). In SH animals, alcohol exposure did not affect baseline number of doublecortin-positive (DCX+) cells, which was consistent with our expectations, while WR/WR, but not WR/EC, successfully increased the number of DCX+ cells in suckle control (SC) and sham-intubated (SI) animals compared to SH animals. In addition, no baseline alterations to total amount of dendritic material were found in the AE group. WR/WR, but not WR/EC, increased the total dendritic material within SC and SI animals. Interestingly, an increase in dendritic material was not observed within AE animals, suggesting that AE animals are not gaining as much benefit from WR/WR on this measure as the control animals. These results confirm that aerobic exercise is a positive intervention as measured by adult hippocampal neurogenesis. Additionally, it is possible that total dendritic material is negatively affected enough by alcohol exposure in a way that disrupts the ability of these cells to be affected exercise as profoundly.
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Keywords
Neuroscience