title: TRPV1 in Salivary Gland Epithelial Cells Is Not Involved in Salivary Secretion via Transcellular Pathway.
abstract: Transient receptor potential vanilloid subtype 1 (TRPV1) was originally found in sensory neurons. Recently, it has been reported that TRPV1 is expressed in salivary gland epithelial cells (SGEC). However, the physiological role of TRPV1 in salivary secretion remains to be elucidated. We found that TRPV1 is expressed in mouse and human submandibular glands (SMG) and HSG cells, originated from human submandibular gland ducts at both mRNA and protein levels. However, capsaicin (CAP), TRPV1 agonist, had little effect on intracellular free calcium concentration ([Ca(2+)]i) in these cells, although carbachol consistently increased [Ca(2+)]i. Exposure of cells to high temperature (>43℃) or acidic bath solution (pH5.4) did not increase [Ca(2+)]i, either. We further examined the role of TRPV1 in salivary secretion using TRPV1 knock-out mice. There was no significant difference in the pilocarpine (PILO)-induced salivary flow rate between wild-type and TRPV1 knock-out mice. Saliva flow rate also showed insignificant change in the mice treated with PILO plus CAP compared with that in mice treated with PILO alone. Taken together, our results suggest that although TRPV1 is expressed in SGEC, it appears not to play any direct roles in saliva secretion via transcellular pathway.
authors.affiliation: Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea.
authors.forename: Seulki
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea.
authors.forename: Yong-Hwan
authors.initials: YH
authors.lastname: Shin
authors.affiliation: Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea.
authors.forename: Eun
authors.initials: E
authors.lastname: Namkoong
authors.affiliation: Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea.
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Hwang
authors.affiliation: Department of Physiology and Pathophysiology, Peking University Health Science Center, Beijing 100191, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Cong
authors.affiliation: Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology, Beijing 100081, China.
authors.forename: Guangyan
authors.initials: G
authors.lastname: Yu
authors.affiliation: Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Seoul 110-749, Korea.
authors.forename: Kyungpyo
authors.initials: K
authors.lastname: Park
keywords: Capsaicin; Intracellular free calcium concentration; Salivary gland epithelial cells; TRPV1