Effect of cortisol on permeability and tight junction protein transcript abundance in primary cultured gill epithelia from stenohaline goldfish and euryhaline trout

► Effect of cortisol on gill permeability and tight junction protein mRNA was studied. ► Primary cultured gill epithelia from goldfish and rainbow trout were utilized. ► Cortisol elevated transepithelial resistance and reduced paracellular permeability. ► Cortisol elicited few changes in goldfish versus trout tight junction protein mRNA. ► Differences in response may relate to stenohalinity versus euryhalinity.