Cortisol regulates eel ( Anguilla anguilla ) aquaporin 3 (AQP3) mRNA expression levels in gill

• Published in: General and comparative endocrinology Vol. 152; no. 2; pp. 310 - 313
• Main Authors: Cutler, C.P, Phillips, C, Hazon, N, Cramb, G
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2007
• Subjects: Acclimatization - physiology; Anguilla - physiology; Anguilla anguilla; Animals; Aquaporin 3; Aquaporin 3 - genetics; Brackish; Cortisol; Endocrinology & Metabolism; Freshwater; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; Gill; Gills - physiology; Hydrocortisone - blood; Hydrocortisone - pharmacology; Intestine; Intestines - physiology; Marine; mRNA expression; RNA, Messenger - metabolism; Cortisol; Gill; Intestine; Aquaporin 3; mRNA expression
• ISSN: 0016-6480; 1095-6840
• DOI: 10.1016/j.ygcen.2007.01.031

Abstract Previous studies in eel ( Anguilla anguilla ) gill have shown that the expression of the aquaporin 3 (AQP3) water and small solute channel is dramatically decreased (mRNA abundance decreased by up to 97%) when these euryhaline fish are acclimated from freshwater (FW) to seawater (SW). However, AQP3 mRNA expression levels in the intestine following SW-acclimation do not change. The SW-acclimating corticosteroid hormone, cortisol has previously been shown to regulate the expression of aquaporins (particularly AQP1) in eel osmoregulatory tissues in a tissue-specific and isoform-specific fashion. AQP1 is up-regulated in intestine and oesophagus, but down-regulated in kidney, following SW-acclimation in these fish. This study extends knowledge of the regulation of aquaporin expression by cortisol in the eel and shows that elevated levels of this hormone down-regulate AQP3 mRNA expression in the gill in a similar manner to SW-acclimation. However, the smaller magnitude of the changes in branchial AQP3 expression induced by cortisol-infusion (around a 60% decrease), in comparison to those occurring following SW-acclimation, suggest that other factors must also contribute to AQP3 down-regulation. In a similar fashion to the regulation of AQP1 by cortisol, changes in AQP3 expression following hormone infusion appear to be tissue-specific, as little effect was seen on the level of AQP3 expression in the intestine. Again the apparent lack of change in intestinal AQP3 expression following cortisol-infusion mimicked the invariant level of intestinal AQP3 mRNA abundance following SW-acclimation.