Skin l-tryptophan-2,3-dioxygenase and rat hair growth

Isao Ishiguro, Junko Naito, Kuniaki Saito, Yoichi Nagamura

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)


We have identified a new enzyme, skin l-tryptophan-2,3-dioxygenase (skin TDO), that catalyzes the degradation of l-tryptophan into formylkynurenine in rats. The rate of this degradation peaks in all rats at 5 to 6 weeks after birth, and also, among rats depilated at 8 weeks old, at 10 to 11 weeks after birth. We have also observed that the properties of this enzyme are closer to those of hepatic l-tryptophan-2,3-dioxygenase (hepatic TDO) than to indoleamine 2,3-dioxygenase. Although an intraperitoneal injection of l-tryptophan increased the activity of skin TDO to approximately 2.2 times greater than control values, an intraperitoneal injection of hydrocortisone and α-methyl-dl-tryptophan, both compounds known to affect hepatic TDO activity, had no effect on skin TDO activity. The molecular weight of skin TDO was estimated to be 16.0 kDa, which is close to the molecular weight of hepatic TDO, yet a much larger molecule than indoleamine-2,3-dioxygenase. Increased hair growth rates paralleled increased levels of skin TDO activity in 5- to 6-week-old rats, and marked increases in the activity of skin TDO occurred 2 or 3 weeks after depilation. Enzyme activity was also greatest 2 days before the time of maximum hair root length. Therefore, skin TDO may play an important role in the initiation or suppression of rat hair growth.

Original languageEnglish
Pages (from-to)178-182
Number of pages5
JournalFEBS Letters
Issue number1-2
Publication statusPublished - 23-08-1993

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


Dive into the research topics of 'Skin l-tryptophan-2,3-dioxygenase and rat hair growth'. Together they form a unique fingerprint.

Cite this