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Caffeine increases tear volume depending on polymorphisms within the adenosine A2a receptor gene and cytochrome P450 1A2.

Abstract

PURPOSE
The primary aim of the present study was to examine the effect of caffeine on tear volume. The secondary aim was to investigate the relation between caffeine-induced changes in tear volume and polymorphisms in ADORA2A and CYP1A2.
DESIGN
Double-masked, placebo-controlled, crossover study.
PARTICIPANTS
Seventy-eight healthy volunteers were recruited for the study.
METHODS
Subjects participated in 2 sessions in which they received capsules containing either placebo or caffeine. The caffeine capsules were given to the subjects to keep the caffeine volume per body weight within 5 to 7 mg/kg. After caffeine intake, tear meniscus height (TMH) was measured. Subjects provided a blood sample for genotyping.
MAIN OUTCOME MEASURES
Tear meniscus height, single nucleotide polymorphism.
RESULTS
The tear volume increased after caffeine consumption. The net increase in TMH was 0.08 mm (95% confidence interval, 0.05-0.10) greater when participants were given caffeine than when given placebo (P<0.0001). In ADORA2A, the difference in the net increase in TMH for participants who were heterozygous at rs5751876 and rs2298383 was 0.07 mm (P = 0.001) and who were minor homozygous was 0.08 mm (P = 0.007). In CYP1A2, the net increase in TMH for participants who were minor homozygous at rs2472304 was lower than for those who were major homozygous; the difference was 0.06 mm (P = 0.039).
CONCLUSIONS
Caffeine intake increases tear volume and polymorphisms within ADORA2A, and CYP1A2 is associated with the tear increase after caffeine intake. Genetic polymorphisms had a significant effect on tear meniscus that was of limited clinical significance.

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  • Publisher Full Text

    • Authors

    Arita R, Yanagi Y, Honda N, Maeda S, Maeda K, Kuchiba A, Yamaguchi T, Yanagihara Y, Suzuki H, Amano S

    Institution

    Department of Ophthalmology, University of Tokyo School of Medicine, Tokyo, Japan. ritoh@za2.so-net.ne.jp

    Source

    Ophthalmology 119:5 2012 May pg 972-8

    MeSH

    Adult
    Body Constitution
    Caffeine
    Capsules
    Cross-Over Studies
    Cytochrome P-450 CYP1A2
    Double-Blind Method
    Female
    Genotyping Techniques
    Humans
    Male
    Middle Aged
    Polymerase Chain Reaction
    Polymorphism, Single Nucleotide
    Receptor, Adenosine A2A
    Tears
    Young Adult

    Pub Type(s)

    Journal Article
    Randomized Controlled Trial

    Language

    eng

    PubMed ID

    22336631