title: Lower expressions of the human bitter taste receptor TAS2R in smokers: reverse transcriptase-polymerase chain reaction analysis.
abstract: BACKGROUND
  Despite the fact that smokers have deficit in detecting taste, particularly bitter taste, no study has investigated its biological correlate.
  
  
  METHODS
  In this context, we compared the expression of the bitter taste receptor gene, taste 2 receptor (TAS2R) in the tongues of smokers and non-smokers. Tissue samples were collected from the lateral portion of the tongues of 22 smokers and 22 age- and gender-matched healthy volunteers (19 males and three females) with no history of smoking. Reverse transcriptase-polymerase chain reaction was used to examine the expression of TAS2R in the two groups, and the effect of aging on TAS2R expression was also assessed.
  
  
  RESULTS
  TAS2R expression was significantly lower among smokers than non-smokers (t = 6.525, P < .0001, 11.36 ± 6.0 vs. 2.09 ± 2.8, mean ± SD, non-smokers vs. smokers). Further, a positive correlation between age and expression of TAS2R was observed in non-smokers (r = .642, P = .001), but not smokers (r = .124, P = .584). This correlation difference was significant (Z = 1.96, P = .0496).
  
  
  CONCLUSIONS
  Smokers showed a significantly lower expression of the bitter taste receptor gene than non-smokers, which is potentially caused by their inability to acquire such receptors with age because of cigarette smoking, in contrast to non-smokers.
authors.affiliation: Department of food and nutrition, Sanyo Gakuen College, 1-14-1 Hirai, Naka-ward, Okayama 703-8501, Japan.
authors.forename: Mieko
authors.initials: M
authors.lastname: Aoki
authors.affiliation: Department of nutrition and health promotion, Showa Women's University, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Takao
authors.affiliation: School of Medicine, Nihon University, Tokyo, Japan.
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Takao
authors.affiliation: Department of Dentistry and Oral Surgery, Nihon University, Tokyo, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Koike
authors.affiliation: Department of Medicine, Kochi University, Kochi, Japan.
authors.forename: Narufumi
authors.initials: N
authors.lastname: Suganuma
keywords: Cigarette; Human; RT-PCR; TAS2R