Metallothionein gene expression under different time in testicular Sertoli and spermatogenic cells of rats treated with cadmium.
The rodent testes are generally more susceptible to cadmium (Cd)-induced toxicity than the liver. To clarify the molecular mechanism underlying tissue and cell differences in Cd sensitivity, we compared metallothionein (MT) gene expression, MT protein accumulation, and Cd retention under different times in freshly isolated testicular Sertoli and spermatogenic cells and liver of rats treated with Cd. Adult male Sprague-Dawley rats received a s.c. injection of 4.0 micromol Cd/kg and 1, 3, 6, or 24h later and untreated animals (0h) tissue were sampled and testicular Sertoli and spermatogenic cells isolated. 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. Testicular lesions were not grossly or histologically observed in rats treated with 4.0 micromol Cd/kg. In the present study, we demonstrated that the rat testis indeed 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 3h, followed by a decline, in contrast, the mRNA levels in Sertoli cells peaked at 6h. Interestingly, the induction of MT1 mRNA was lower than MT2 mRNA in Sertoli cells and liver of rats treated with Cd. However, the MT1 mRNA levels of spermatogenic cells decreased 0-3h after Cd treatment, followed by an increase; in contrast, MT2 mRNA levels increased 0-3h after Cd treatment, followed by a reduction, but induced extents of them are lower than those of Sertoli cells and liver. Cd exposure substantially increased hepatic MT, but did not increase MT translation in Sertoli and spermatogenic cells. These results indicate: (1) that Cd-induced MT mRNA expression is cell- and time-dependent; (2) that the inability to induce the metal-detoxicating MT protein in response to Cd, might account for higher susceptibility of testes to Cd toxicity and carcinogenesis relative to liver.
Ren
Xu Yi
XY
Department of Biochemistry and Molecular Biology, Second Military Medical University, 200433, Shanghai, China. renxuyi2003@163.com
Zhou
Yong
Y
Zhang
Jian Peng
JP
Feng
Wei Hua
WH
Jiao
Bing Hua
BH
D000818:Animals; D001483:Base Sequence; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D003001:Cloning, Molecular; D015870:Gene Expression / Q000187:drug effects*; D008099:Liver / Q000166:cytology / Q000187:drug effects; D008297:Male; D008668:Metallothionein / Q000096:biosynthesis* / Q000235:genetics*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012708:Sertoli Cells / Q000187:drug effects / Q000378:metabolism*; D013091:Spermatogenesis / Q000187:drug effects*; D013737:Testis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects
D012333:RNA, Messenger; D002104:Cadmium; D008668:Metallothionein