title: Human bitter perception correlates with bitter receptor messenger RNA expression in taste cells.
abstract: BACKGROUND
  Alleles of the receptor gene TAS2R38 are responsible in part for the variation in bitter taste perception of 6-n-propylthiouracil (PROP) and structurally similar compounds (eg, glucosinolates in cruciferous vegetables). At low concentrations, people with the PAV ("taster" amino acid sequence) form of TAS2R38 perceive these bitter compounds, whereas most with the AVI ("nontaster" amino acid sequence) form do not; heterozygotes (PAV/AVI) show the widest range of bitter perception.
  
  
  OBJECTIVE
  The objectives were to examine individual differences in expression of PAV-TAS2R38 messenger RNA (mRNA) among heterozygotes, to test the hypotheses that the abundance of allele-specific gene expression accounts for the variation in human bitter taste perception, and to relate to dietary intake of bitter-tasting beverages and foods.
  
  
  METHODS
  Heterozygous individuals (n = 22) provided psychophysical evaluation of the bitterness of PROP, glucosinolate-containing broccoli juice, non-glucosinolate-containing carrot juice, and several bitter non-TAS2R38 ligands as well as dietary recalls. Fungiform taste papillae were examined for allele-specific TAS2R38 expression by using quantitative polymerase chain reaction.
  
  
  RESULTS
  PAV-TAS2R38 mRNA expression was measured in 18 of 22 heterozygous subjects. Relative expression varied widely and positively correlated with ratings of bitterness intensity of PROP (P = 0.007) and broccoli juice (P = 0.004) but not of the control solutions carrot juice (P = 0.26), NaCl (P = 0.68), caffeine (P = 0.24), or urea (P = 0.47). Expression amounts were related to self-reported recent and habitual caffeine intake (P = 0.060, P = 0.005); vegetable intake was too low to analyze.
  
  
  CONCLUSIONS
  We provide evidence that PAV-TAS2R38 expression amount correlates with individual differences in bitter sensory perception and diet. The nature of this correlation calls for additional research on the molecular mechanisms associated with some individual differences in taste perception and food intake. The trial was registered at clinicaltrials.gov as NCT01399944.
authors.affiliation: Monell Chemical Senses Center, Philadelphia, PA.
authors.forename: Sarah V
authors.initials: SV
authors.lastname: Lipchock
authors.forename: Julie A
authors.initials: JA
authors.lastname: Mennella
authors.forename: Andrew I
authors.initials: AI
authors.lastname: Spielman
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Reed
mesh_terms: D000483:Alleles; D001628:Beverages / Q000032:analysis; D018552:Daucus carota; D004032:Diet; D005247:Feeding Behavior; D015870:Gene Expression; D005961:Glucosinolates; D006579:Heterozygote; D006801:Humans; D016133:Polymerase Chain Reaction; D011441:Propylthiouracil; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics* / Q000502:physiology; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000737:chemistry*; D055697:Taste Perception / Q000235:genetics* / Q000502:physiology*; D000098706:Taste Receptors, Type 2
chemical_list: D005961:Glucosinolates; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D000098706:Taste Receptors, Type 2; D011441:Propylthiouracil
references.citation: Curr Biol. 2006 Sep 19;16(18):R792-4
references.pmid: 16979544
references.citation: Am J Clin Nutr. 2003 Feb;77(2):313-8
references.pmid: 12540388
references.citation: Hum Mol Genet. 2010 Nov 1;19(21):4278-85
references.pmid: 20675712
references.citation: Am J Clin Nutr. 2000 Dec;72(6):1424-35
references.pmid: 11101467
references.citation: Chem Senses. 1996 Jun;21(3):323-34
references.pmid: 8670711
references.citation: J Food Compost Anal. 2009 Dec 1;22(Supplement 1):S48-S51
references.pmid: 20161418
references.citation: Chem Senses. 2010 Feb;35(2):157-70
references.pmid: 20022913
references.citation: J Am Diet Assoc. 1989 Dec;89(12):1786-94
references.pmid: 2592710
references.citation: Chem Senses. 2012 Nov;37(9):869-81
references.pmid: 22977065
references.citation: J Am Diet Assoc. 1993 Jul;93(7):790-6
references.pmid: 8320406
references.citation: Chemosens Percept. 2010 Dec 1;3(3-4):137-148
references.pmid: 21157576
references.citation: Chem Senses. 2013 Jul;38(6):475-84
references.pmid: 23632915
references.citation: J Neurosci. 2007 Nov 14;27(46):12630-40
references.pmid: 18003842
references.citation: Science. 2003 Feb 21;299(5610):1221-5
references.pmid: 12595690
references.citation: Chem Senses. 2006 Jun;31(5):403-13
references.pmid: 16527870
references.citation: Chem Senses. 2013 May;38(4):289-92
references.pmid: 23429242
references.citation: MMWR Morb Mortal Wkly Rep. 2010 Sep 10;59(35):1125-30
references.pmid: 20829745
references.citation: Pediatrics. 2005 Feb;115(2):e216-22
references.pmid: 15687429
references.citation: Curr Biol. 2005 Jul 26;15(14):1257-65
references.pmid: 16051168
references.citation: Chem Senses. 2011 Mar;36(3):311-9
references.pmid: 21163912
references.citation: BMC Genet. 2010 Jul 01;11:60
references.pmid: 20594349
references.citation: Chem Senses. 2011 Jan;36(2):161-7
references.pmid: 20980355
references.citation: Percept Psychophys. 2001 Jul;63(5):761-76
references.pmid: 11521845
references.citation: J Vis Exp. 2010 Sep 18;(42):
references.pmid: 20972388
references.citation: Physiol Behav. 2004 Aug;82(1):109-14
references.pmid: 15234598
references.citation: Curr Biol. 2005 Feb 22;15(4):322-7
references.pmid: 15723792
references.citation: Dev Psychobiol. 2003 Sep;43(2):120-7
references.pmid: 12918091
references.citation: Chem Senses. 2010 Oct;35(8):685-92
references.pmid: 20551074
references.citation: Am J Epidemiol. 2005 Oct 15;162(8):806-14
references.pmid: 16120695
references.citation: J Clin Invest. 2012 Nov;122(11):4145-59
references.pmid: 23041624
references.citation: Hum Mol Genet. 2011 Sep 1;20(17):3437-49
references.pmid: 21672920
references.citation: Curr Biol. 2007 Aug 21;17(16):1403-8
references.pmid: 17702579
references.citation: Chem Senses. 2008 Mar;33(3):255-65
references.pmid: 18209019
references.citation: PLoS Genet. 2011 Apr;7(4):e1002033
references.pmid: 21490707
references.citation: Cell. 2000 Mar 17;100(6):703-11
references.pmid: 10761935
references.citation: Phytochemistry. 2001 Jan;56(1):5-51
references.pmid: 11198818
references.citation: Cell. 2000 Mar 17;100(6):693-702
references.pmid: 10761934
references.citation: Psychopharmacology (Berl). 2006 May;185(4):514-23
references.pmid: 16541243