Footedness for scratching itchy eyes in rodents

Yukitoshi Katayama, Ayane Miura, Tatsuya Sakamoto, Keiko Takanami, Hirotaka Sakamoto

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


The neural bases of itchy eye transmission remain unclear compared with those involved in body itch. Here, we show in rodents that the gastrin-releasing peptide receptor (GRPR) of the trigeminal sensory system is involved in the transmission of itchy eyes. Interestingly, we further demonstrate a difference in scratching behaviour between the left and right hindfeet in rodents; histamine instillation into the conjunctival sac of both eyes revealed right-foot biased laterality in the scratching movements. Unilateral histamine instillation specifically induced neural activation in the ipsilateral sensory pathway, with no significant difference between the activations following left- and right-eye instillations. Thus, the behavioural laterality is presumably due to right-foot preference in rodents. Genetically modified rats with specific depletion of Grpr-expressing neurons in the trigeminal sensory nucleus caudalis of the medulla oblongata exhibited fewer and shorter histamine-induced scratching movements than controls and eliminated the footedness. These results taken together indicate that the Grpr-expressing neurons are required for the transmission of itch sensation from the eyes, but that foot preference is generated centrally. These findings could open up a new field of research on the mechanisms of the laterality in vertebrates and also offer new potential therapeutic approaches to refractory pruritic eye disorders.

Original languageEnglish
Article number20221126
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1985
Publication statusPublished - Oct 26 2022


  • footedness
  • gastrin-releasing peptide receptor
  • histamine
  • itchy eyes

ASJC Scopus subject areas

  • General Biochemistry,Genetics and Molecular Biology
  • General Immunology and Microbiology
  • General Environmental Science
  • General Agricultural and Biological Sciences


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