title: Environmental and cortisol-mediated control of Ca(2+) uptake in tilapia (Oreochromis mossambicus).
abstract: Ca(2+) is a vital element for many physiological processes in vertebrates, including teleosts, which live in aquatic environments and acquire Ca(2+) from their surroundings. Ionocytes within the adult gills or larval skin are critical sites for transcellular Ca(2+) uptake in teleosts. The ionocytes of zebrafish were found to contain transcellular Ca(2+) transporters, epithelial Ca(2+) channel (ECaC), plasma membrane Ca(2+)-ATPase 2 (PMCA2), and Na(+)/Ca(2+) exchanger 1b (NCX1b), providing information about the molecular mechanism of transcellular Ca(2+) transports mediated by ionocytes in fish. However, more evidence is required to establish whether or not a similar mechanism of transcellular Ca(2+) transport also exists in others teleosts. In the present study, ecac, pmca2, and ncx1 were found to be expressed in the branchial ionocytes of tilapia, thereby providing further support for the mechanism of transcellular Ca(2+) transport through ionocytes previously proposed for zebrafish. In addition, we also reveal that low Ca(2+) water treatment of tilapia stimulates Ca(2+) uptake and expression of ecac and cyp11b (the latter encodes a cortisol-synthesis enzyme). Treatment of tilapia with exogenous cortisol (20 mg/l) enhanced both Ca(2+) influx and ecac expression. Therefore, increased cyp11b expression is suggested to enhance Ca(2+) uptake capacity in tilapia exposed to low Ca(2+) water. Furthermore, the application of cortisol receptor antagonists revealed that cortisol may regulate Ca(2+) uptake through glucocorticoid and/or mineralocorticoid receptor (GR and/or MR) in tilapia. Taken together, the data suggest that cortisol may activate GR and/or MR to execute its hypercalcemic action by stimulating ecac expression in tilapia.
authors: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC.|National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Aichi, Japan.
authors: Chia-Hao
authors: CH
authors: Lin
authors: Department of Biological Sciences and Technology, National University of Tainan, Tainan, 70005, Taiwan, ROC.
authors: Wei-Chun
authors: WC
authors: Kuan
authors: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC.
authors: Bo-Kai
authors: BK
authors: Liao
authors: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC.
authors: Ang-Ni
authors: AN
authors: Deng
authors: Department of Biological Sciences and Technology, National University of Tainan, Tainan, 70005, Taiwan, ROC. dytseng@mail.nutn.edu.tw.
authors: Deng-Yu
authors: DY
authors: Tseng
authors: Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, ROC. pphwang@gate.sinica.edu.tw.
authors: Pung-Pung
authors: PP
authors: Hwang
mesh_terms: D000064:Acclimatization; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D005880:Gills / Q000378:metabolism; D006854:Hydrocortisone / Q000378:metabolism* / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D018161:Receptors, Mineralocorticoid / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000235:genetics / Q000378:metabolism; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism; D017210:Tilapia / Q000378:metabolism*
chemical_list: D029941:Fish Proteins; D011965:Receptors, Glucocorticoid; D018161:Receptors, Mineralocorticoid; D019831:Sodium-Calcium Exchanger; D050916:TRPV Cation Channels; C110374:sodium-calcium exchanger 1; D053499:Plasma Membrane Calcium-Transporting ATPases; D002118:Calcium; D006854:Hydrocortisone
keywords: Ca2+ influx; Cortisol; ECaC; Ionocyte; Tilapia