Effect of cortisol on the physiology of cultured pavement cell epithelia from freshwater trout gills

Abstract

Cortisol had dose-dependent effects on the electrophysiological, permeability, and ion-transporting properties of cultured pavement cell epithelia derived from freshwater rainbow trout gills and grown on cell culture filter supports. Under both symmetrical (L15 media apical/L15 media basolateral) and asymmetrical (freshwater apical/L15 media basolateral) culture conditions, cortisol treatment elevated transepithelial resistance, whereas permeability of epithelia to a paracellular permeability marker (polyethylene glycol-4000) decreased. Cortisol did not alter the Na(+)-K(+)-ATPase activity or the total protein content of the cultured preparations. During 24-h exposure to asymmetrical conditions, the net loss rates of both Na(+) and Cl(-) to the water decreased with increasing cortisol dose, an important adaptation to dilute media. Unidirectional Na(+) and Cl(-) flux measurements and the application of the Ussing flux-ratio criterion revealed cortisol-induced active uptake of both Na(+) and Cl(-) under symmetrical culture conditions together with an increase in transepithelial potential (positive on the basolateral side). Under asymmetrical conditions, cortisol did not promote active ion transport across the epithelium. These experiments provide evidence for the direct action of cortisol on cultured pavement cell epithelia and, in particular, emphasize the importance of cortisol for limiting epithelial permeability.

Tight junction protein gene expression patterns and changes in transcript abundance during development of model fish gill epithelia

“…In support of the idea that a reduction in cldn-32a occurs in association with reduced gill epithelium permeability and, therefore, may play a role in enhancing its barrier properties are observations of a cortisol-induced reduction in cldn-32a mRNA abundance in cultured PVC epithelia derived from the puffer fish (Tetraodon nigroviridis) (Bui et al, 2010). Cortisol has been documented to reduce the paracellular permeability of model gill epithelia derived from trout (Kelly and Wood, 2001;Chasiotis et al, 2010), tilapia and goldfish (Chasiotis and Kelly, 2011b). Therefore, these new observations, together with the limited distribution of cldn-32a (see Fig.…”

“…Once insert-cultured epithelia reach a plateau in TER, they are not documented to exhibit any further increase in TER or decrease in paracellular permeability unless they are experimentally manipulated [e.g. by the addition of cortisol (Kelly and Wood, 2001)]. Therefore, if changes in TJ protein mRNA abundance are conservative during the first 108 h of culture, it seems unlikely that marked changes would occur during an extended plateau phase.…”

The physiology of fish at low pH: the zebrafish as a model system

“…Consistent with their increased levels during acid exposure, these hormones are able to promote ion uptake (Flik and Perry, 1989;Kumai et al, 2012a;, increase H + -ATPase activity for acid secretion (Lin and Randall, 1993), and reduce epithelial permeability Chasiotis et al, 2010;Kelly and Wood, 2001;Kwong and Perry, 2013a;Tipsmark et al, 2009). Therefore, these hormones may play critical roles during the acclimation of fish to acidic environments.…”

Glucocorticoid and mineralocorticoid receptors regulate paracellular permeability in a primary cultured gill epithelium

“…Using primary cultured 'reconstructed' gill preparations, a role for cortisol in the regulation of gill epithelial permeability has been established (see Kelly and Wood, 2001;Kelly and Wood, 2002;Wood et al, 2002). Measurements of epithelial permeability, such as transepithelial resistance (TER), paracellular radiotracer movement (i.e.…”

“…For example, cultured trout gill epithelia have been shown to respond to levels of cortisol as low as 10ngml -1 (Kelly and Wood, 2001). Recent studies indicate that cortisol-induced alterations in the paracellular permeability characteristics of cultured gill preparations relate to changes in the abundance of tight junction (TJ) proteins and transcript encoding these proteins (Bui et al, 2010;Chasiotis et al, 2010).…”