Basic Research
Copyright ©The Author(s) 2003. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 15, 2003; 9(7): 1554-1558
Published online Jul 15, 2003. doi: 10.3748/wjg.v9.i7.1554
Expression of metallothionein gene at different time in testicular interstitial cells and liver of rats treated with cadmium
Xu-Yi Ren, Yong Zhou, Jian-Peng Zhang, Wei-Hua Feng, Bing-Hua Jiao
Xu-Yi Ren, Yong Zhou, Jian-Peng Zhang, Wei-Hua Feng, Bing-Hua Jiao, Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai 200433, China
Author contributions: All authors contributed equally to the work.
Supported by the National Natural Science Foundation of China, No. 39970631
Correspondence to: Dr. Xu-Yi Ren, Department of Biochemistry and Molecular Biology, Second Military Medical University, Shanghai 200433, China. renxuyi2003@163.com
Telephone: +86-21-25070306-8008 Fax: +86-21-65334344
Received: December 30, 2002
Revised: March 1, 2003
Accepted: March 4, 2003
Published online: July 15, 2003
Abstract

AIM: Rodent testes are generally more susceptible to cadmium (Cd)-induced toxicity than liver. To clarify the molecular mechanism of Cd-induced toxicity in testes, we compared metallothionein (MT) gene expression, MT protein accumulation, and Cd retention at different time in freshly isolated testicular interstitial cells and liver of rats treated with Cd.

METHODS: Adult male Sprague-Dawley rats weighing 250-280 g received a s.c injection of 4.0 μmol Cd/kg and were euthanized by CO2 asphyxiation 1 h, 3 h, 6 h, or 24 h later. Tissue was sampled and testicular interstitial cells were isolated. There were three replicates per treatment and 3 animals per replicate for RNA analyses, others, three replicates per treatment and one animal per replicate. MT1 and MT2 mRNA levels were determined by semi-quantitative RT-PCR analysis followed by densitometry scanning, and MT was estimated by the enzyme-linked immunosorbent assay (ELISA) method. Cadmium content was determined by atomic absorption spectrophotometry. The same parametersd were also analyzed in the liver, since this tissue unquestionably accumulate MT.

RESULTS: The rat testis expressed MT1 and MT2, the major isoforms. We also found that untreated animals contained relatively high basal levels of both isoform mRNA, which were increased after Cd treatment in liver and peaked at 3 h, followed by a decline. In contrast, the mRNA levels in interstitial cells peaked at 6 h. Interestingly, the induction of MT1 mRNA was lower than MT2 mRNA in liver of rat treated with Cd, but it was opposite to interstitial cells. Cd exposure substantially increased hepatic MT (3.9-fold increase), but did not increase MT translation in interstitial cells.

CONCLUSION: Cd-induced expression of MT isoforms is not only tissue dependent but also time-dependent. The inability to induce the metal-detoxicating MT-protein in response to Cd, may account for a higher susceptibility of testes to Cd toxicity and carcinogenesis compared to liver.

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