title: Involvement of glucocorticoid in induction of lingual T1R3 in rodents.
abstract: We previously reported that in rats, chronic exposure to stress inhibits the induction of the common receptor (T1R3) for sweet and umami tastes. Here, we investigated whether endogenous glucocorticoids (GCs) might be responsible for this inhibition. In addition, we used mouse taste-bud cells (TB cells) expressing T1R3 to examine the effect of exogenous GC on T1R3 induction. Both adrenal glands were removed from rats [adrenalectomized (ADX) rats] and T1R3 mRNA expression in fungiform papillae was examined by real-time RT-PCR. T1R3 mRNA expression was significantly reduced in the ADX rats (versus sham-ADX rats). The reduced mRNA expression was restored to the level seen in the sham-ADX rats by administration of dexamethasone (DEX) at the smallest dose tested (0.1ng/kg, i.p.). However, with larger doses of DEX (10 and 1000ng/kg, i.p.) there was no such restoration (i.e., the expression level did not differ from that seen in ADX rats). Expression of the mRNA for the GC receptor-α was detected in mouse TB cells by RT-PCR. Significantly reduced T1R3 mRNA expression, as measured by real-time RT-PCR, was observed in TB cells at 24h after application of DEX (0.1, 1.0, or 10μM). These results suggest that in rodents: (a) a low concentration of endogenous GC is necessary and sufficient for induction of T1R3 expression, and that higher concentrations may actually inhibit such induction, and (b) this inhibitory effect may be due, at least in part, to a direct action of GC on taste cells.
authors.affiliation: Division of Integrative Physiology, Department of Physiology, Tottori University Faculty of Medicine, Tottori 683-8503, Japan; Division of Oral and Maxillofacial Biopathological Surgery, Department of Medicine of Sensory and Motor Organs, Tottori University Faculty of Medicine, Tottori 683-8503, Japan.
authors.forename: Nobuhumi
authors.initials: N
authors.lastname: Ogawa
authors.affiliation: Division of Molecular and Genetic Medicine, Department of Genetic Medicine and Regenerative Therapeutics, Tottori University Institute of Regenerative Medicine and Biofunction, Tottori 683-8503, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Kanki
authors.affiliation: Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Tokyo 125-8585, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Honda
authors.affiliation: Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Tokyo 125-8585, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tomooka
authors.affiliation: Division of Oral and Maxillofacial Biopathological Surgery, Department of Medicine of Sensory and Motor Organs, Tottori University Faculty of Medicine, Tottori 683-8503, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ryoke
authors.affiliation: Division of Integrative Physiology, Department of Physiology, Tottori University Faculty of Medicine, Tottori 683-8503, Japan. Electronic address: watanabe@med.tottori-u.ac.jp.
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000315:Adrenalectomy; D000818:Animals; D002460:Cell Line; D003907:Dexamethasone / Q000008:administration & dosage / Q000031:analogs & derivatives; D004305:Dose-Response Relationship, Drug; D005938:Glucocorticoids / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011965:Receptors, Glucocorticoid / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D013650:Taste Buds / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D015854:Up-Regulation
chemical_list: D005938:Glucocorticoids; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D011965:Receptors, Glucocorticoid; C411470:glucocorticoid receptor alpha; C431926:taste receptors, type 1; C004180:dexamethasone 21-phosphate; D003907:Dexamethasone
keywords: Adrenalectomy; Dexamethasone; Mouse; RT-PCR; Rat; T1R3