title: Effects of cortisol and salinity challenge on water balance in developing larvae of tilapia (Oreochromis mossambicus).
abstract: Effects of exogenous cortisol on drinking rate and water content in developing larvae of tilapia (Oreochromis mossambicus) were examined. Both freshwater- and seawater-adapted larvae showed increases in drinking rates with development. Drinking rates of seawater-adapted larvae were about four- to ninefold higher than those of freshwater-adapted larvae from day 2 to day 5 after hatching. Seawater-adapted larvae showed declines in drinking rate and water content at 4 and 14 h, respectively, after immersion in 10 mg L(-1) cortisol. In the case of freshwater-adapted larvae, the drinking rate decreased after 8 h of cortisol immersion, while the water content did not show a significant change even after 32 h of cortisol immersion. In a subsequent experiment of transfer from freshwater to 20 ppt (parts per thousand, salinity) seawater, immersion in 10 mg L(-1) cortisol for 8-24 h enhanced the drinking rate in larvae at 4 h after transfer, but no significant difference was found in water contents between cortisol-treated and control groups following transfer. These results suggest that cortisol is involved in the regulation of drinking activity in developing tilapia larvae.
authors.affiliation: Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan, Republic of China.
authors.forename: L Y
authors.initials: LY
authors.lastname: Lin
authors.forename: C F
authors.initials: CF
authors.lastname: Weng
authors.forename: P P
authors.initials: PP
authors.lastname: Hwang
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D004327:Drinking Behavior; D006854:Hydrocortisone / Q000494:pharmacology*; D017210:Tilapia / Q000502:physiology*; D014867:Water / Q000737:chemistry; D014882:Water-Electrolyte Balance / Q000502:physiology*
chemical_list: D014867:Water; D006854:Hydrocortisone