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Hormonal Control of Aquaporin 3 in Tilapia Gill: Direct Actions of Prolactin and Cortisol
Author(s) -
Breves Jason,
Inokuchi Mayu,
Yamaguchi Yoko,
Seale Andre,
Watanabe Soichi,
Lerner Darren,
Kaneko Toyoji,
Grau E
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.843.5
Subject(s) - euryhaline , aquaporin 3 , prolactin , tilapia , biology , medicine , endocrinology , aquaporin , hormone , osmoregulation , epithelium , microbiology and biotechnology , salinity , fish <actinopterygii> , ecology , fishery , genetics
In teleosts, aquaporins (Aqps) are expressed within key osmoregulatory epithelia where they mediate the movements of water and selected solutes across cell membranes. We investigated endocrine control of Aqp3 in the gill of euryhaline Mozambique tilapia, with particular attention to prolactin (Prl), growth hormone, and cortisol. Branchial aqp3 mRNA levels were modulated following salinity challenges, with enhanced aqp3 expression upon transfer from seawater to fresh water (FW). Accordingly, extensive Aqp3‐immunoreactivity was localized to cell membranes of branchial epithelium in FW‐acclimated animals. By transferring hypophysectomized tilapia to FW, we identified that a pituitary factor(s) is required for the elevation in Aqp3 levels that accompanies FW acclimation. The diminished capacity of hypophysectomized animals to activate Aqp3 expression in FW was rescued by Prl replacement, an effect blocked by co‐injection with cortisol. Prl stimulated aqp3 expression in cultured gill filaments in a concentration‐related manner. Consistent with in vivo responses, co‐incubation with cortisol blocked Prl‐stimulated aqp3 expression in cultured filaments. Our data indicate that Prl and cortisol act upon branchial epithelium to mediate salinity‐dependent Aqp3 expression in tilapia. Collectively, these data provide the first evidence that Prl modulates Aqp expression in a vertebrate osmoregulatory tissue.