Effects of Exogenous Cortisol and Progesterone on Metallothionein Expression and Tolerance to Waterborne Cadmium in Tilapia (Oreochromis mossambicus)

助孕酮和皮質醇對吳郭魚（Oreochromis mossambicus）金屬硫蛋白表現及鎘耐性之作用

吳淑美(Su-Mei Wu) ； 周宜瑩(Yi-Ying Chou) ； 鄧昂妮(Am-Ni Deng)

《Zoological Studies》 41卷1期 (2002/01) Pp. 111-118

摘要

本研究之目的為驗證假說： 糖皮質激素會誘發吳郭魚金屬硫蛋白表現進而增加對水中鎘之耐性。探討皮質醇與黃體酮前處理對吳郭魚（Oreochromis mossambicus）金屬硫蛋白表現及對鎘耐性之影響。吳郭魚成魚（全長4-5 cm、體重5.0-6.0 g）或仔魚（全長0.5-0.7 cm、體重0.012-0.017 g），投餵以0（對照組）、50（低劑量）、125（中劑量）和250 mg/kg（高劑量）皮質醇與黃體酮10天。投餵實驗後，偵測成魚肝臟或仔魚全魚之金屬硫蛋白含量及鎘處理後的死亡率。結果顯示投餵皮質醇與黃體酮可以增加吳郭魚成魚在鎘水中之活存。中劑量及高劑量黃體酮具有提高吳郭魚成魚金屬硫蛋白表現之作用，而皮質醇則作用不明。浸泡鎘後，高劑量皮質醇及中、高劑量的黃體酮都顯著地增加金屬硫蛋白之產生。然而在仔魚有不同之結果，皮質醇與黃體酮前處理對仔魚鎘耐性或金屬硫蛋白誘導均無明顯之作用。我們推論：類固醇激具有參與誘導吳郭魚成魚金屬硫蛋白合成與重金屬解毒之機制，但是此機制在仔魚尚不明瞭。

關鍵字

醣皮質固醇 ； 金屬硫蛋白 ； 鎘 ； 耐受力 ； 吳郭魚

並列摘要

The object of the present study was to test the hypothesis that glucocorticoids can induce the expression of metallothionein (MT) which consequently enhances the tolerance to metal toxicity in tilapia (Oreochromis mossambicus). Adult tilapia (4-5 cm in total length and 5.0-6.0 g in body weight) and larval tilapia (0.5-0.7 cm in total length and 0.012-0.017 g in body weight) were reared with artificial feed containing 0 (control), 50 (low dose), 125 (medium dose), or 250 mg/kg (high dose) of cortisol or progesterone for 10 d. Liver and wholebody contents of MT and mortality in tilapia upon Cd2+ exposure were examined after the steroid-rearing experiments. Both cortisol and progesterone significantly increased survival rates in adult fish after Cd2+ challenge. Treatment with middle and high doses of progesterone significantly stimulated the expression of MT in adult fish, but stimulation by cortisol showed no significant effect on MT expression. More MT was expressed after Cd2+ challenge in both cortisol- and progesterone-treated groups. However, exogenous steroids caused no significant effect on MT contents or survival upon Cd2+ challenge in tilapia larvae. This suggests that cortisol and progesterone are involved in metal-detoxification mechanisms in adult tilapia via regulating the expression of MT, but the occurrence of this pathway in developing fish is unclear.

並列關鍵字

Corticosteroid ； Metallothionein ； Cadmium ； Tolerance ； Tilapia