Health Effects Research Program, Toxicology Portfolio, U.S. Army Institute of Public Health, Aberdeen Proving Ground, MD 21010-5403, USA.
Ecotoxicology. 2012 Nov;21(8):2372-90. doi: 10.1007/s10646-012-0993-1. Epub 2012 Sep 14.
Evaluation of multiple-stressor effects stemming from habitat degradation, climate change, and exposure to chemical contaminants is crucial for addressing challenges to ecological and environmental health. To assess the effects of multiple stressors in an understudied taxon, the western fence lizard (Sceloporus occidentalis) was used to characterize the individual and combined effects of food limitation, exposure to the munitions constituent 2,4,6-trinitrotoluene (TNT), and Plasmodium mexicanum (lizard malaria) infection. Three experimental assays were conducted including: Experiment I--TNT × Food Limitation, Experiment II--Food Limitation × Malaria Infection, and Experiment III--TNT × Malaria Infection. All experiments had a 30 day duration, the malaria treatment included infected and non infected control lizards, food limitation treatments included an ad libitum control and at least one reduced food ration and TNT exposures consisting of daily oral doses of corn oil control or a corn oil-TNT suspension at 5, 10, 20, 40 mg/kg/day. The individual stressors caused a variety of effects including: reduced feeding, reduced testes mass, anemia, increased white blood cell (WBC) concentrations and increased mass of liver, kidney and spleen in TNT exposures; reduced cholesterol, WBC concentrations and whole body, testes and inguinal fat weights given food limitation; and increased WBC concentrations and spleen weights as well as decreased cholesterol and testes mass in malaria infected lizards. Additive and interactive effects were found among certain stressor combinations including elimination of TNT-induced hormesis for growth under food limitation. Ultimately, our study indicates the potential for effects modulation when environmental stressors are combined.
评估由栖息地退化、气候变化和接触化学污染物引起的多种胁迫效应对于解决生态和环境健康挑战至关重要。为了评估未充分研究的分类单元中的多种胁迫效应，使用西部围栏蜥蜴（Sceloporus occidentalis）来描述食物限制、暴露于弹药成分 2,4,6-三硝基甲苯（TNT）和 Plasmodium mexicanum（蜥蜴疟疾）感染的个体和联合效应。进行了三个实验测定，包括：实验 I-TNT×食物限制、实验 II-食物限制×疟疾感染和实验 III-TNT×疟疾感染。所有实验均持续 30 天，疟疾处理包括感染和非感染对照蜥蜴，食物限制处理包括随意进食对照和至少一种减少的食物量，TNT 暴露包括每日口服玉米油对照或玉米油-TNT 悬浮液，剂量为 5、10、20、40mg/kg/天。单个胁迫源引起了多种效应，包括：TNT 暴露导致摄食量减少、睾丸质量减少、贫血、白细胞（WBC）浓度增加以及肝、肾和脾质量增加；食物限制导致胆固醇、WBC 浓度和全身、睾丸和腹股沟脂肪重量减少；疟疾感染导致 WBC 浓度和脾脏重量增加以及胆固醇和睾丸质量减少。某些胁迫源组合之间发现了累加和交互效应，包括食物限制下 TNT 诱导生长的兴奋效应的消除。最终，我们的研究表明，当环境胁迫源组合时，可能会发生效应调节。
