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A Role For 11‐Deoxycortisol In The Regulation Of Tight Junction Permeability In An Extant Agnathan
Author(s) -
Zimina Anna,
Kolosov Dennis,
Wilkie Michael P,
Kelly Scott P
Publication year - 2016
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.30.1_supplement.1223.25
Subject(s) - paracellular transport , lamprey , biology , extant taxon , tight junction , hormone , vertebrate , petromyzon , endocrinology , microbiology and biotechnology , permeability (electromagnetism) , fishery , evolutionary biology , biochemistry , membrane , gene
Corticosteroid hormones are important regulators of paracellular permeability across vertebrate epithelia. In aquatic vertebrates such as teleost fishes, cortisol reduces the paracellular permeability of the gill epithelium, which in a freshwater (FW) environment has been proposed to contribute to reduced passive ion loss under conditions of environmental or systemic perturbation. However, it is not known whether corticosteroids contribute to the regulated movement of solutes across the paracellular pathway in less derived vertebrates, such as agnathans. This gap in knowledge speaks to the difficulty of pinning down the identity of corticosteroid hormones in agnathans. But recent studies have revealed that 11‐deoxycortisol is the only circulating corticosteroid with high affinity and specificity to the sea lamprey corticosteroid receptor. This knowledge now presents us with an opportunity to examine whether 11‐deoxycortisol contributes to the regulation of paracellular ion transport in sea lamprey. Given the strong link between corticosteroids and paracellular solute movement across epithelia of more derived fishes, as well as other vertebrates, it can be hypothesized that 11‐deoxycortisol will play a similar role in the lamprey. Using the stenohaline FW larval form of the sea lamprey, the objectives of this study were to examine the dose‐dependent effects of 11‐deoxycortisol on: (1) endpoints of salt and water balance and (2) the molecular physiology of the larval lamprey TJ complex in iono/osmoregulatory organs such as the gill and kidney. Results indicated that 11‐deoxycortisol treatment of larval sea lamprey dose‐dependently altered endpoints of salt and water balance as well as the abundance of select TJ proteins. Therefore a third objective of this study was to examine whether changes brought about by 11‐deoxycortisol are beneficial to larval lamprey in terms of coping with ionoregulatory disturbance (i.e. abrupt exposure to an ion deficient environment). While data on the molecular physiology of the lamprey TJ complex suggests that the changes produced by 11‐deoxycortisol are useful for ion retention in a hyposmotic or ion‐deficient environment, net flux of Na+ and Cl‐ upon abrupt exposure to ion‐poor water paradoxically suggest that transepithelial solute permeability is greater following 11‐deoxycortisol treatment. Overall, data from these studies provide evidence to support the hypothesis that 11‐deoxycortisol contributes to the regulation of TJ permeability in an extant FW larval agnathan, but this may differ from the role that corticosteroids such as cortisol play in more derived fishes. Support or Funding Information This research was supported by Natural Sciences and Engineering Research Council of Canada.