title: Hormonal regulation of aquaporin 3: opposing actions of prolactin and cortisol in tilapia gill.
abstract: Aquaporins (Aqps) are expressed within key osmoregulatory tissues where they mediate the movement of water and selected solutes across cell membranes. We leveraged the functional plasticity of Mozambique tilapia (Oreochromis mossambicus) gill epithelium to examine how Aqp3, an aquaglyceroporin, is regulated in response to osmoregulatory demands. Particular attention was paid to the actions of critical osmoregulatory hormones, namely, prolactin (Prl), growth hormone and cortisol. Branchial aqp3 mRNA levels were modulated following changes in environmental salinity, with enhanced aqp3 mRNA expression upon transfer from seawater to freshwater (FW). Accordingly, extensive Aqp3 immunoreactivity was localized to cell membranes of branchial epithelium in FW-acclimated animals. Upon transferring hypophysectomized tilapia to FW, we identified that a pituitary factor(s) is required for Aqp3 expression in FW. Replacement with ovine Prl (oPrl) was sufficient to stimulate Aqp3 expression in hypophysectomized animals held in FW, an effect blocked by coinjection with cortisol. Both oPrl and native tilapia Prls (tPrl177 and tPrl188) stimulated aqp3 in incubated gill filaments in a concentration-related manner. Consistent with in vivo responses, coincubation with cortisol blocked oPrl-stimulated aqp3 expression in vitro Our data indicate that Prl and cortisol act directly upon branchial epithelium to regulate Aqp3 in tilapia. Thus, within the context of the diverse actions of Prl on hydromineral balance in vertebrates, we define a new role for Prl as a regulator of Aqp expression.
authors.affiliation: Department of BiologySkidmore College, Saratoga Springs, New York, USA jbreves@skidmore.edu.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Breves
authors.affiliation: Hawai'i Institute of Marine BiologyUniversity of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA Department of Aquatic BioscienceGraduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Inokuchi
authors.affiliation: Hawai'i Institute of Marine BiologyUniversity of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Hawai'i Institute of Marine BiologyUniversity of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA.
authors.forename: Andre P
authors.initials: AP
authors.lastname: Seale
authors.affiliation: Department of BiologySkidmore College, Saratoga Springs, New York, USA.
authors.forename: Bethany L
authors.initials: BL
authors.lastname: Hunt
authors.affiliation: Department of Aquatic BioscienceGraduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo, Japan.
authors.forename: Soichi
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Hawai'i Institute of Marine BiologyUniversity of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA University of Hawai'i Sea Grant College ProgramUniversity of Hawai'i at Mānoa, Honolulu, Hawai'i, USA.
authors.forename: Darren T
authors.initials: DT
authors.lastname: Lerner
authors.affiliation: Department of Aquatic BioscienceGraduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo, Japan.
authors.forename: Toyoji
authors.initials: T
authors.lastname: Kaneko
authors.affiliation: Hawai'i Institute of Marine BiologyUniversity of Hawai'i at Mānoa, Kāne'ohe, Hawai'i, USA.
authors.forename: E Gordon
authors.initials: EG
authors.lastname: Grau
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D051400:Aquaporin 3 / Q000235:genetics / Q000378:metabolism*; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism*; D005618:Fresh Water; D005880:Gills / Q000187:drug effects / Q000378:metabolism*; D006854:Hydrocortisone / Q000494:pharmacology*; D011388:Prolactin / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D012623:Seawater; D012756:Sheep; D017210:Tilapia / Q000235:genetics / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000187:drug effects
chemical_list: D029941:Fish Proteins; D012333:RNA, Messenger; D051400:Aquaporin 3; D011388:Prolactin; D006854:Hydrocortisone
keywords: aquaporin; cortisol; gill; osmoregulation; prolactin