Osmoregulatory action of 17β‐estradiol in the gilthead sea bream Sparus auratus

摘要: The osmoregulatory action of 17beta-estradiol (E2) was examined in the euryhaline teleost Sparus auratas. In a first set experiments, fish were injected once with vegetable oil containing E2 (1, 2 and 5 microg/g body weight), transferred 12h after injection from sea water (SW, 38 ppt salinity) to hypersaline (HSW, 55 ppt) or brackish (BW, sampled later (i.e. 24 h post-injection). second experiment, intraperitoneally coconut alone (10 weight) days. same days treatment, each group HSW, BW SW 4 (9 post-implant). Gill Na+,K+ -ATPase activity, plasma levels, osmolality, levels ions (sodium calcium), glucose, lactate, protein, triglyceride, hepatosomatic index examined. Transfer HSW produced no significant effects on any parameters assessed. treatment did not affect parameter. resulted decrease osmolality sodium but gill activity. A single dose attenuated these transfer BW, without effect An implant for significantly increased calcium, index, metabolic parameters, oil-implanted (sham) fish, during elevated -ATPase. activity remained unaltered E2-treated BW. However, E2-implant), decreased respect HSW- BW-transferred fish. Shams showed trygliceride plasma, while those only displayed levels. higher protein change other plasmatic glucose These results substantiate chronic stimulatory