Fish Physiology and Biochemistry

, Volume 17, Issue 1, pp 295–301

Osmoregulatory actions of growth hormone in juvenile tilapia (Oreochromis niloticus)

  • B. Xu
  • H. Miao
  • P. Zhang
  • D. Li
Article

DOI: 10.1023/A:1007750022878

Cite this article as:
Xu, B., Miao, H., Zhang, P. et al. Fish Physiology and Biochemistry (1997) 17: 295. doi:10.1023/A:1007750022878

Abstract

Growth hormone (GH) effectively promotes seawater (SW) adaptation in salmonids, but little is known of its effect in tilapias. Experiments were performed to investigate the effects of recombinant eel GH (reGH) on osmoregulatory actions and ultrastructural features of gill chloride cells in juvenile tilapia, Oreochromis niloticus. Tilapia showed a markedly improved SW survival, when directly transferred from freshwater (FW) to 62.5% SW 24h after a single reGH injection (0.25 or 2.5 µg g-1) or 3 reGH injections (0.25 µg g-1 every other day). Plasma Na+ and Mg2+ levels were significantly reduced by reGH (0.25 and 2.5 µg g-1) compared with saline injections; Ca2+ concentrations were reduced significantly by high dose of reGH (2.5 µg g-1) after SW transfer. However, fish failed to survive more than 24h when directly transferred to 70% SW, although the fish treated with reGH could survive longer than the controls. When examined by electron microscopy, the chloride cells were identified as mitochondrion-rich and an extensive tubular system was induced by GH treatment. The results of the present study suggest that, similar to its effect on salmonids, GH also exerts acute osmoregulatory actions and enhances SW adaptation in juvenile tilapia. GH also stimulates the differentiation of chloride cells toward SW adaptation.

tilapiaOreochromis niloticusosmoregulationgrowth hormoneseawater adaptationplasma ionsgill chloride cellsmitochondrion-richtubular system

Copyright information

© Kluwer Academic Publishers 1997

Authors and Affiliations

  • B. Xu
    • 1
  • H. Miao
    • 2
  • P. Zhang
    • 3
  • D. Li
    • 1
  1. 1.Fisheries CollegeOcean University of QingdaoQingdaoP.R. China
  2. 2.Marine Life Sciences CollegeOcean University of QingdaoQingdaoP.R. China
  3. 3.Laboratory of Experimental Marine Biology, Institute of OceanologyAcademia SinicaQingdaoP.R. China