title: Self-Administration of Smokeless Tobacco Products in Rats.
abstract: OBJECTIVE
  Preclinical abuse liability assessment is an essential component of tobacco regulatory science. The goal of this project was to evaluate the relative abuse liability of smokeless tobacco products in rats using aqueous extracts of those products. These extracts provide exposure to an extensive range of nicotine and non-nicotine tobacco constituents as occurs in humans.
  
  
  METHODS
  Rats were trained to self-administer either nicotine alone or extracts of Camel Snus or Kodiak smokeless tobacco at an equivalent nicotine unit dose. In Experiment 1, the relative reinforcing efficacy of these formulations was assessed in adults and adolescents using a progressive ratio schedule under limited-access conditions. In Experiment 2, relative reinforcing efficacy was assessed in adolescents under unlimited-access conditions using behavioral economic demand curve analysis.
  
  
  RESULTS
  The reinforcing efficacy of nicotine formulations was higher in adolescents than adults, but no difference was observed between formulations in either age group. Similarly, there was no difference in elasticity of demand between formulations in adolescents.
  
  
  CONCLUSIONS
  The present findings suggest that the abuse liability of these smokeless tobacco products is similar to nicotine alone, and that nicotine dose is the primary determinant of the reinforcing efficacy of systemic exposure to these products.
authors.affiliation: Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN.
authors.forename: Mark G
authors.initials: MG
authors.lastname: LeSage
authors.affiliation: Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN.
authors.forename: Danielle
authors.initials: D
authors.lastname: Burroughs
authors.affiliation: Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN.
authors.forename: Peter
authors.initials: P
authors.lastname: Muelken
authors.affiliation: Department of Medicine, Minneapolis Medical Research Foundation, Minneapolis, MN.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Harris
keywords: abuse liability; behavioral economics; nicotine; progressive-ratio schedule; rat; self-administration; smokeless tobacco extracts