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Vol. 45 No. 3, 2006
Cortisol and Copper Induce Metallothionein Expression in
Three Tissues of Tilapia (Oreochromis mossambicus) in Organ Culture
Su-Mei Wu*, Chun-Che Chen, Yi-Chun Lee, Hsien-Tai Leu, and Nia-Sung Lin
Department of Aquatic Biosciences, National Chiayi University, Chiayi, Taiwan 600
Su-Mei Wu, Chun-Che Chen, Yi-Chun Lee, Hsien-Tai Leu, and Nia-Sung Lin (2006) The
aim of this study was to determine the major organ for metallothionein
(MT) synthesis among the liver, gills, and intestines, and which organ
exhibits the highest heavy metal accumulation. In a review of past
studies, some researchers still doubted that the liver contains the
highest MT content. We decided to perform an in vitro study, and hypothesized that MT expression is affected by endogenous in vivo factors resulting in an irregular phenomenon. Therefore, in this in vitro
study, we compared MT expressions in these 3 important organs. The 3
organs were cultured in L15 media with 100 ng/ml cortisol and 100 µM
CuSO4
for 24, 48, 72, and 96 h. The MT contents of the 3 organs appeared to
be time dependent from 24 to 72 h, but decreased after 96 h. Hepatic
tissue exhibited the highest MT content among the 3 organs. With the
cortisol and CuSO4 dose-response tests, a dose-dependent response was
only seen in the intestines after treatments with various
concentrations of cortisol and CuSO4. When organs were
incubated in different culture media for 72 h, the hepatic tissue also
showed the highest Cu accumulation. Summarizing these results, we
suggest that the liver is the major organ synthesizing MT and
accumulating Cu in comparison to the gills and intestines.
Key words: Metallothionein, Cortisol, Copper, Tilapia, Organ culture.
*Correspondence: Tel: 886-5-2717850. Fax: 886-5-2717847. E-mail: sumei@mail.ncyu.edu.tw
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