Paramount levels of ergothioneine transporter SLC22A4 mRNA in boar seminal vesicles and cross-species analysis of ergothioneine and glutathione in seminal plasma

J Physiol Pharmacol. 2011 Aug;62(4):411-9.


Ergothioneine (ET) is a unique natural antioxidant which mammalia acquire exclusively from their food. Recently, we have discovered an ET transporter (ETT; gene symbol SLC22A4). The existence of a specific transporter suggests a beneficial role for ET; however, the precise physiological purpose of ET is still unclear. A conspicuous site of high extracellular ET accumulation is boar seminal plasma. Here, we have investigated whether ETT is responsible for specific accumulation of ET in the boar reproductive tract. The putative ETT from pig (ETTp) was cloned and validated by functional expression in 293 cells. The highest levels of ETTp mRNA were detected by real-time RT-PCR in seminal vesicles, eye, and kidney; much less was present in bulbourethral gland, testis, and prostate. By contrast, there was virtually no ETT mRNA in rat seminal vesicles. ET content in boar reproductive tissues, determined by LC-MS/MS, closely matched the ETT expression profile. Thus, strong and specific expression of ETTp in boar seminal vesicles explains high accumulation of ET in this gland and hence also in seminal plasma. Previous reports suggest that the glutathione (GSH) content of seminal plasma correlates directly with ET content; however, a comprehensive analysis across several species is not available. We have measured ET and GSH in seminal plasma from human, boar, bull, stallion, and rabbit by LC-MS/MS. GSH levels in seminal plasma do not correlate with ET levels. This suggests that the function of ET, at least in this extracellular context, does not depend on redox cycling with GSH.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Chickens
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • Ergothioneine / metabolism*
  • Glutathione / metabolism*
  • HEK293 Cells
  • Horses
  • Humans
  • Male
  • Organic Cation Transport Proteins / biosynthesis*
  • Organic Cation Transport Proteins / genetics
  • Oxidation-Reduction
  • Plasmids
  • RNA, Messenger / metabolism*
  • Rabbits
  • Rats, Wistar
  • Real-Time Polymerase Chain Reaction
  • Semen / metabolism*
  • Seminal Vesicles / metabolism*
  • Species Specificity
  • Sus scrofa / genetics
  • Sus scrofa / metabolism*
  • Symporters
  • Transfection


  • DNA, Complementary
  • Organic Cation Transport Proteins
  • RNA, Messenger
  • SLC22A4 protein, human
  • Symporters
  • Ergothioneine
  • Glutathione