Tobacco smoke diminishes neurogenesis and promotes gliogenesis in the dentate gyrus of adolescent rats

Brain Res. 2011 Sep 21;1413:32-42. doi: 10.1016/j.brainres.2011.07.041. Epub 2011 Jul 24.

Abstract

Brain disorders and environmental factors can affect neurogenesis and gliogenesis in the hippocampus. These studies investigated the effects of chronic exposure to tobacco smoke on progenitor cell proliferation and the survival and phenotype of new cells in the dentate gyrus of adolescent rats. The rats were exposed to tobacco smoke for 4h/day for 14 days. To investigate cell proliferation, the exogenous marker 5-bromo-2'-deoxyuridine (BrdU, 200mg/kg, ip) was administered 2h into the 4-h smoke exposure session on day 14. The rats were sacrificed 2-4h after the administration of BrdU. To investigate cell survival, the same dose of BrdU was administered 24h before the start of the 14-day smoke exposure period. These rats were sacrificed 24h after the last smoke exposure session. Tobacco smoke exposure decreased both the number of dividing progenitor cells (-19%) and the number of surviving new cells (-20%), labeled with BrdU in the dentate gyrus. The decrease in cell proliferation was not associated with an increase in apoptotic cell death, as shown by TUNEL analysis. Colocalization studies indicated that exposure to tobacco smoke decreased the number of new immature neurons (BrdU/DCX-positive) and transition neurons (BrdU/DCX/NeuN-positive) and increased the number of new glial cells (BrdU/GFAP-positive). These findings demonstrate that exposure to tobacco smoke diminishes neurogenesis and promotes gliogenesis in the dentate gyrus of adolescent rats. These effects may play a role in the increased risk for depression and cognitive impairment in adolescent smokers.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Animals
  • Cell Proliferation / drug effects
  • Dentate Gyrus / cytology*
  • Dentate Gyrus / drug effects
  • Dentate Gyrus / physiology*
  • Male
  • Neural Inhibition / drug effects
  • Neural Inhibition / physiology*
  • Neural Stem Cells / cytology
  • Neural Stem Cells / drug effects
  • Neural Stem Cells / physiology
  • Neurogenesis / drug effects
  • Neurogenesis / physiology*
  • Neuroglia / cytology*
  • Neuroglia / drug effects
  • Neuroglia / physiology*
  • Rats
  • Rats, Wistar
  • Smoking / adverse effects*
  • Smoking / pathology