Cigarette smoke induces DNA damage and alters base-excision repair and tau levels in the brain of neonatal mice

Toxicol Sci. 2011 Oct;123(2):471-9. doi: 10.1093/toxsci/kfr187. Epub 2011 Jul 21.

Abstract

The prenatal and perinatal periods of brain development are especially vulnerable to insults by environmental agents. Early life exposure to cigarette smoke (CS), which contains both genotoxicants and oxidants, is considered an important risk factor for both neurodevelopmental and neurodegenerative disorders. Yet, little is known regarding the underlying pathogenetic mechanisms. In the present study, neonatal Swiss ICR (CD-1) albino mice were exposed to various concentrations of CS for 4 weeks and the brain examined for lipid peroxides, DNA damage, base-excision repair (BER) enzymes, apoptosis, and levels of the microtubule protein tau. CS induced a dose-dependent increase in both malondialdehyde and various types of DNA damage, including single-strand breaks, double-strand breaks, and DNA-protein cross-links. However, the CS-induced DNA damage in the brain returned to basal levels 1 week after smoking cessation. CS also modulated the activity and distribution of the BER enzymes 8-oxoguanine-DNA-glycosylase (OGG1) and apyrimidinic/apurinic endonuclease (APE1) in several brain regions. Normal tau (i.e., three-repeat tau, 3R tau) and various pathological forms of tau were also measured in the brain of CS-exposed neonatal mice, but only 3R tau and tau phosphorylated at serine 199 were significantly elevated. The oxidative stress, genomic dysregulation, and alterations in tau metabolism caused by CS during a critical period of brain development could explain why CS is an important risk factor for both neurodevelopmental and neurodegenerative disorders appearing in later life.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Apoptosis / drug effects
  • Body Weight / drug effects
  • Brain / drug effects*
  • Brain / metabolism
  • Cerebral Cortex / drug effects
  • Cerebral Cortex / pathology
  • DNA Damage
  • DNA Glycosylases / metabolism
  • DNA Repair / drug effects*
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / metabolism
  • Inhalation Exposure
  • Lipid Peroxidation / drug effects
  • Longevity / drug effects
  • Mice
  • Neurons / drug effects
  • Neurons / pathology
  • Nicotiana*
  • Oxidative Stress / drug effects
  • Smoke / adverse effects*
  • tau Proteins / metabolism*

Substances

  • Smoke
  • tau Proteins
  • DNA Glycosylases
  • Ogg1 protein, mouse
  • Apex1 protein, mouse
  • DNA-(Apurinic or Apyrimidinic Site) Lyase