title: Conjunctival expression of the P2Y2 receptor and the effects of 3% diquafosol ophthalmic solution in dogs.
abstract: Conjunctival epithelial and goblet cell P2Y2 nucleotide receptors regulate ion transport and secretory function. Diquafosol is a P2Y2 purinergic receptor agonist that stimulates secretion of aqueous tear components from conjunctival epithelial cells and secretion of mucin from conjunctival goblet cells. In humans suffering from keratoconjunctivitis sicca (dry eye), topical administration of diquafosol improves corneal epithelial integrity and stabilises the tear film. The aim of the present study was to investigate P2Y2 receptor expression and to determine the effect of topical administration of diquafosol on mucin and aqueous tear production in dogs. Canine conjunctival P2Y2 receptor expression was evaluated by Western blotting and immunohistochemical analysis. The effect of diquafosol on mucin secretion was evaluated by examining mucin-5 subtype AC (MUC5AC) concentration in tears. The effect of diquafosol on aqueous secretions was evaluated by performing the Schirmer tear test (STT) and phenol red thread test. Expression of the P2Y2 receptor was confirmed in canine bulbar and palpebral conjunctivae and receptors were identified at the conjunctival epithelial and goblet cell surface. Tear MUC5AC concentration significantly increased after administration of 3% diquafosol ophthalmic solution, although neither STT nor phenol red thread test values showed any significant change after diquafosol instillation. Topical ocular administration of 3% diquafosol might improve corneal epithelial disorders in dogs through stabilisation of the tear film, by virtue of an increase in MUC5AC secretion.
authors.affiliation: Department of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan. Electronic address: terakado.vet@gmail.com.
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Terakado
authors.affiliation: Department of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Yogo
authors.affiliation: Department of Veterinary Anatomy, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Kohara
authors.affiliation: Department of Veterinary Anatomy, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Soeta
authors.affiliation: Department of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nezu
authors.affiliation: Department of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Harada
authors.affiliation: Department of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Hara
authors.affiliation: Department of Veterinary Anatomy, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Amasaki
authors.affiliation: Department of Veterinary Surgery, Nippon Veterinary and Life Science University, 1-7-1 Kyonancho, Musashino, Tokyo 180-8602, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tagawa
mesh_terms: D000818:Animals; D003228:Conjunctiva / Q000378:metabolism*; D004285:Dogs / Q000378:metabolism*; D009883:Ophthalmic Solutions; D011122:Polyphosphates / Q000494:pharmacology*; D058912:Purinergic P2Y Receptor Agonists / Q000494:pharmacology*; D058473:Receptors, Purinergic P2Y2 / Q000235:genetics / Q000378:metabolism*; D014500:Uracil Nucleotides / Q000494:pharmacology*
chemical_list: D009883:Ophthalmic Solutions; D011122:Polyphosphates; D058912:Purinergic P2Y Receptor Agonists; D058473:Receptors, Purinergic P2Y2; D014500:Uracil Nucleotides; C403315:diquafosol
keywords: Conjunctiva; Diquafosol; Dog; Mucin secretion; P2Y(2) receptor