Wang Mei-Zhen, Jia Xiu-Ying
College of Life and Environment Sciences, Hangzhou Normal University, Hangzhou, Zhejiang, 310036, People's Republic of China.
Ecotoxicology. 2009 Jan;18(1):94-9. doi: 10.1007/s10646-008-0262-5. Epub 2008 Sep 3.
We have investigated the chronic effects of low concentrations of lead (Pb) on oxidative damage and DNA damage in testes of the frog Rana nigromaculata. Sixty adult male frogs were randomly divided into six groups of ten. Based on the levels of the Integrated Wastewater Discharge Standard (GB 8978-1996) of China, five groups (II-VI) were treated by epidermal absorption with a PbNO(3) solution at concentrations of 0.1, 0.2, 0.4, 0.8, 1.6 mg/l, respectively. The first group (I), which served as a control, was treated with distilled water only. Thirty days after treatment, all frogs were sacrificed and the testis tissues removed for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels. DNA damage, including indicators of damage rate, DNA tail length (TL), and DNA tail moment (TM), was also analyzed by comet assays. Our data suggest that MDA levels in all treatment groups and GSH levels in the 0.2-1.6 mg/l Pb groups increased significantly relative to the controls (P < 0.01). Treatment with Pb at concentrations >0.4 mg/l also increased DNA damage rate and TM, while TL increased when the Pb level was >0.2 mg/l (P < 0.01 for DNA damage rate and TM, P < 0.05 for TL). Positive correlations were also found between DNA damage levels in the testes and MDA levels (r = 0.796 for DNA damage rate, r = 0.811 for TL, r = 0.796 for TM; P < 0.01 for all) as well between MDA and GSH levels (r = 0.455, P < 0.05) in the testes. Results from MDA measurements indicated that Pb-induced DNA damage in the testes of R. nigromaculata was possibly due to oxidative damage. Taken together, we conclude that Pb can induce male reproductive toxicity in R. nigromaculata.
我们研究了低浓度铅（Pb）对黑斑蛙睾丸氧化损伤和DNA损伤的慢性影响。60只成年雄性青蛙被随机分为6组，每组10只。根据中国《污水综合排放标准》（GB 8978 - 1996）的标准，五组（II - VI）分别通过表皮吸收0.1、0.2、0.4、0.8、1.6 mg/l浓度的PbNO₃溶液进行处理。第一组（I）作为对照，仅用蒸馏水进行处理。处理30天后，处死所有青蛙，取出睾丸组织用于测量丙二醛（MDA）和谷胱甘肽（GSH）水平。还通过彗星试验分析了DNA损伤，包括损伤率、DNA尾长（TL）和DNA尾矩（TM）等指标。我们的数据表明，所有处理组的MDA水平以及0.2 - 1.6 mg/l铅组的GSH水平相对于对照组均显著升高（P < 0.01）。浓度>0.4 mg/l的铅处理也增加了DNA损伤率和TM，而当铅水平>0.2 mg/l时TL增加（DNA损伤率和TM的P < 0.01，TL的P < 0.05）。在睾丸中的DNA损伤水平与MDA水平之间（DNA损伤率r = 0.796，TL r = 0.811，TM r = 0.796；所有P < 0.01）以及MDA和GSH水平之间（r = 0.455，P < 0.05）也发现了正相关。MDA测量结果表明，铅诱导的黑斑蛙睾丸DNA损伤可能是由于氧化损伤。综上所述，我们得出结论，铅可诱导黑斑蛙雄性生殖毒性。
