Effect of cortisol on some osmoregulatory parameters of the teleost, Oreochromis niloticus L., after transference from freshwater to seawater

A. Fontaínhas-Fernandes, E.F. Gomes, Mª.A. Reis-Henriques, J. Coimbra
2003 Arquivo Brasileiro de Medicina Veterinária e Zootecnia  
This trial was conducted in order to determine the effects of cortisol on salt water acclimation of tilapia Oreochromis niloticus (L.). Tilapia (n=42) were injected intraperitoneally with cortisol and then were directly transferred from freshwater (FW) to 15‰ salt water (SW). Changes in plasma osmolality, chloride ion concentration (Cl-), plasma level of cortisol and gill Na+, K+-ATPase activity were measured at 6, 12, 24, 48, 72 and 168 hours after transference to 15‰ SW. Plasma osmolality and
more » ... Cl- increased immediately after transference until 12-24 h. The fish injected with cortisol (F) showed higher plasma levels of cortisol than those from control group (C) that maintained the initial levels during the experiment. Gill Na+, K+-ATPase activity of C fish began to increase at first hours after transference and peak at 48h. The differences between gill Na+, K+-ATPase activity of F and C groups were significant (P<0.05) in FW, which confirm the effect of exogenous cortisol.
doi:10.1590/s0102-09352003000500008 fatcat:epmgfkxbjjbpdbvf534iw7x75m