Changes in Serum Steroid Hormones and Vitellogenin Levels in Cultured Female European Eels Anguilla anguilla during Artificially Induced Ovarian Development |
| |
| Authors: | Hiroaki Chiba Kenji Iwatsuki Kazuo Hayami Akihiko Hara Kohei Yamauchi |
| |
| Institution: | School of Fisheries Sciences, Kitasato University, Sanriku. Iwate 022–01 Japan;Biological Institute, Faculty of Education, Kagawa University, Takamatsu. Kagawa 760 Japan;Three Bond Co., Ltd, Harama. Hachioji, Tokyo 193 Japan;Nanae Fish Culture Experimental Station, Faculty of Fisheries, Hokkaido University, Hakodate 041–11 Japan;Department of Biology, Faculty of Fisheries, Hokkaido University. Hakodate 041 Japan |
| |
| Abstract: | Changes in serum concentrations of estradiol-17β, testosterone, 17α,20βdihydroxy-4-pregnen-3-one, and vitellogenin were investigated during ovarian development induced by injection of a salmon pituitary extract in cultured European eel Anguilla anguilla . Vitellogenesis was induced with a weekly dose of 50 mg pituitary extract/kg body weight. In eels receiving that dose, gonadsomatic indices ranged from 20–43% after the 10th–11th weekly injection. Body weights were relatively stable during vitellogenesis, but increased dramatically during final maturation. Serum estradiol-17β levels increased slightly during vitellogenesis and peaked at an average of 6.95 ng/mL at final maturation. The profile of serum vitellogenin followed that of estradiol-17β which increased markedly from an average of 0.36 to 20.72 mg/mL. Control levels of vitellogenin were undetectable throughout the study. Average serum levels of testosterone increased to a peak of 17.74 ng/mL in the early stage of vitellogenesis, followed by a sharp drop to initial levels (3.86 ng/mL) in the late stage of vitellogenesis, and then increased again to an average of 8.84 ng/mL at the final maturation stage. Serum 17α,20β-dihydroxy-4-pregnen-3-one was not detected (<50 pg/mL) throughout the experiment. Profiles of serum estradiol-17β, testosterone, and vitellogenin observed during ovarian development appear different from those found in salmonids and other teleosts. This study indicates, however, that cultured European eels are a useful model for study of gonadal maturation in the eel. |
| |
| Keywords: | |
|
|
