Nicotine improves cognitive deficits of dopamine transporter knockout mice without long-term tolerance

Neuropsychopharmacology. 2007 Dec;32(12):2465-78. doi: 10.1038/sj.npp.1301385. Epub 2007 Mar 21.

Abstract

Various studies suggest a dysfunction of nicotinic neurotransmission in schizophrenia and establish that patients suffering from schizophrenia and attention deficit hyperactivity disorder (ADHD) have a high tobacco consumption, potentially for the purpose of self-medication. Owing to its neuroprotective and procognitive effects, transdermal nicotine was proposed to be an effective treatment of some neurodegenerative and psychiatric diseases. Mice deficient in the dopamine transporter (DAT KO) exhibit a phenotype reminiscent of schizophrenia and ADHD, including hyperdopaminergia, hyperactivity, paradoxical calming by methylphenidate and cognitive deficits, some of which being improved by antipsychotic agents. We recently demonstrated that nicotinic receptor content and function were profoundly modified in DAT KO mice. In this study, we assessed the effects of a chronic nicotine treatment in the drinking water on the nicotine-induced locomotion, anxiety status and learning performance. Chronically nicotine-treated DAT KO mice were always hypersensitive to the hypolocomotor effect of nicotine without tolerance and did not exhibit the anxiogenic effect of nicotine treatment observed in WT mice. Very interestingly, both acute and chronic nicotine treatments greatly improved their deficits in the cued and spatial learning, without eliciting tolerance. We speculate that the procognitive effects of nicotine in DAT KO mice are related to the upregulation of alpha7 nicotinic receptors in the hippocampus, amygdala, and prelimbic cortex, all areas involved in cognition. Data from our studies on DAT KO mice shed light on the nicotine self-medication in psychiatric patients and suggest that nicotinic agonists could favorably lead to additional therapy of psychiatric diseases.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Analysis of Variance
  • Animals
  • Autoradiography / methods
  • Behavior, Animal / drug effects
  • Cognition Disorders / drug therapy*
  • Cognition Disorders / genetics*
  • Disease Models, Animal
  • Dopamine Plasma Membrane Transport Proteins / deficiency*
  • Drinking / drug effects
  • Drug Administration Schedule
  • Drug Interactions
  • Male
  • Maze Learning / drug effects
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Motor Activity / drug effects
  • Motor Activity / genetics
  • Nicotine / administration & dosage*
  • Nicotinic Agonists / administration & dosage*
  • Nicotinic Antagonists / administration & dosage
  • Reaction Time / drug effects
  • Receptors, Nicotinic / metabolism
  • Time Factors

Substances

  • Dopamine Plasma Membrane Transport Proteins
  • Nicotinic Agonists
  • Nicotinic Antagonists
  • Receptors, Nicotinic
  • Nicotine