MAO-B knockout mice exhibit deficient habituation of locomotor activity but normal nicotine intake

M. Lee, K. Chen, J. C. Shih, N. Hiroi

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Low levels of monoamine oxidase-B (MAO-B) activity, such as those observed in smokers, are also associated with behavioral traits such as a heightened responsiveness to novelty. However, the exact mechanism by which low MAO-B activity influences smoking and heightened responsiveness to novelty is still poorly understood. We used MAO-B knockout (KO) mice to test the hypothesis that MAO-B concomitantly affects locomotor responses in a novel inescapable open field and nicotine intake. Male wild-type (WT) and MAO-B KO mice were placed in an inescapable open field and their horizontal locomotor activity was measured for 30 min per day for 5 days. MAO-B KO mice exhibited impaired within-session habituation of locomotor activity, as compared to WT mice. Separate groups of male WT and MAO-B KO mice were individually housed in their home cages with two water bottles. One of the bottles contained tap water and the other contained nicotine (0, 3.125, 6.25, 12.5, 25, 50 or 100μg/ml). The total amount of water and nicotine solution consumed was measured every three days for 16 days. MAO-B KO mice and WT mice consumed equal amounts of nicotine and exhibited comparable concentration-dependent nicotine preference and aversion over a period of 16 days. The data suggest that the absence of MAO-B impairs the ability of mice to habituate in the inescapable environment, but does not alter their nicotine intake.

Original languageEnglish (US)
Pages (from-to)216-227
Number of pages12
JournalGenes, Brain and Behavior
Issue number4
StatePublished - Aug 2004
Externally publishedYes


  • Knockout
  • Locomotor activity
  • MAO-B
  • Nicotine
  • Open field

ASJC Scopus subject areas

  • Neurology
  • Genetics
  • Behavioral Neuroscience


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