Grantee Research Project Results
1999 Progress Report: Developmental Effects of Fish-Borne Toxicants in the Rat
EPA Grant Number: R825812Title: Developmental Effects of Fish-Borne Toxicants in the Rat
Investigators: Seegal, Richard F. , Schantz, Susan L.
Institution: The State University of New York , University of Illinois Urbana-Champaign
EPA Project Officer: Aja, Hayley
Project Period: December 15, 1997 through December 15, 2000
Project Period Covered by this Report: December 15, 1998 through December 15, 1999
Project Amount: $470,560
RFA: Issues in Human Health Risk Assessment (1997) RFA Text | Recipients Lists
Research Category: Human Health
Objective:
Epidemiological studies suggest an association between consumption of contaminated Great Lakes fish by pregnant women and behavioral deficits in their children. Polychlorinated biphenyls (PCBs) are correlated with these dysfunctions suggesting that PCBs may either be the relevant toxicant or serve as a marker for the relevant toxicant(s). The objective of this project is to determine if the neurobehavioral effects attributed to PCBs are due either to other neuroactive contaminants or to additive or synergistic interactions between PCBs and other contaminants. The project will determine the class(es) of contaminants in Lake Ontario (LO) salmon that induce neurobehavioral and neurochemical alterations in rats following perinatal exposure to lyophilized LO salmon and solvent-extracted contaminants from LO salmon. The contaminant concentrations of these diets, as well as the resulting brain levels of the contaminants, will be characterized. Experiments will include three dose levels at all exposure conditions, providing data useful in the design of new risk assessment methods. These data will provide more accurate information concerning the risk due to fish consumption and the importance of incorporating data on the identity and levels of the contaminants and their possible interactive effects on neurological endpoints.Progress Summary:
Developmental Exposure to Fish-Borne Contaminants. We have completed exposure of three of four cohorts of 27 litters each. Dams were exposed from gestational day 6 through weaning (21 days of age) to one of nine diets (control chow; 20 percent lyophilized Pacific Ocean [PO] salmon; extracted PO oil equivalent to 20 percent lyophilized salmon; 7, 14, and 20 percent lyophilized LO salmon; and extracted LO oil equivalent to 7, 14, and 20 percent lyophilized salmon).Developmental Landmarks and Neurochemical and Neurobehavioral Testing. On postnatal day 2, we determined, for each treatment, the number of litters delivered, the number of pups per litter, the sex ratio of the litter, the total litter weight, and the ano-genital distances for both male and female pups. During the lactational period, we determined righting reflex and the date at which eye opening occurred; at weaning, we determined the weight of the offspring, and liver and brain weights. We also determined the dates of sexual maturity?vaginal opening and preputial separation. At present, we are collecting developmental data from the third cohort.
For each cohort, at 21 days of age one male and one female pup from each litter were sacrificed for brain neurochemical and contaminant residue analyses. At 60 days of age one male and one female pup from each litter were shipped to Dr. Schantz at the University of Illinois at Urbana? Champaign for behavioral testing. At present, animals from the second cohort are being tested. Because of the preliminary nature of the data (small number of litters at each treatment), we have elected to delay statistical analyses of the developmental, neurochemical, and behavioral data until all cohorts of the experiment are complete.
Characterization of Contaminants in Exposure Diets and Brain Tissue. Preliminary contaminant characterization of the PO and LO salmon has been completed and includes PCBs, pesticides, dioxins, dibenzofurans, inorganic metals, and methylmercury. We are completing development and validation of a dual column gas chromatographic method for confirming PCB congeners and pesticides that includes an automated program for comparing the data from the two columns for PCB congener confirmation. This technique will allow us to report congener-specific PCB data from both the exposure diets and the brains of offspring exposed to the diets; it also will allow us to follow the transfer of contaminants from the diets to the offspring. These results will be the first published data on congener-specific analysis of brain PCB levels in rodents following exposure to contaminated fish from the Great Lakes.
To separate the contaminants from the oil for subsequent experiments, we will use semipermeable membrane dialysis because this technique minimizes the destruction of contaminants that might occur if sulfuric acid was used to destroy the lipids. The prepared extracts will be characterized using the same methods as those used for the exposure diets and brain tissue.
Neurobehavioral Testing. During the first year of funding, an automated behavioral testing laboratory was assembled. A behavioral test battery was programmed and the battery was piloted on a set of practice animals. During the current reporting period, the test battery was validated by evaluating animals exposed to two of the key individual contaminants present in Great Lakes fish?PCBs and dioxins. This approach allowed us to test the operant battery under real experimental conditions and confirm that the test battery was providing results consistent with findings for these two contaminants previously reported in the literature. These experiments also provided important data on individual contaminants for comparison with the findings from rats exposed to the complex mixture of chemicals present in Great Lakes fish.
The first cohort of offspring exposed to the fish diets (one male and one female from each litter; 3 litters/exposure group; 54 rats/cohort) began the behavioral test battery in February 1999. All rats in the cohort have completed the open field locomotor activity test, the motor skill reaching task, operant lever press shaping, spatial discrimination-reversal learning, the visual discrimination-reversal learning task, and the delayed spatial alternation task. The second cohort began testing in September 1999, and the third cohort will begin testing in March 2000. Again, because of the small number of litters in each exposure group that have completed testing, we have elected to delay presentation of any preliminary data.
This first experiment of the study will allow us to characterize the neurobehavioral effects associated with exposure to the complex mixture of contaminants found in Great Lakes fish, and provide information about the role of metals, particularly methylmercury, in mediating these effects.
Future Activities:
By the end of the current year, we will have completed the first experiment (four cohorts) comparing behavioral and neurochemical effects in offspring of rats exposed to lyophilized LO salmon, solvent extract of LO salmon, or comparably treated PO salmon. These data will allow us to: (1) characterize the behavioral effects of the complex mixture of chemicals found in Great Lakes fish; and (2) determine whether methylmercury, which is present in the lyophilized fish but absent from the extracted fish oil, is important in mediating the behavioral effects of the complex mixture of contaminants found in the fish. In additional experiments, the contaminants will be separated from the fish oil and will be fractionated to determine the role that different classes of organic pollutants play in mediating the neurobehavioral deficits.Journal Articles on this Report : 5 Displayed | Download in RIS Format
| Other project views: | All 8 publications | 5 publications in selected types | All 5 journal articles |
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Bemis JC, Seegal RF. Polychlorinated biphenyls and methylmercury act synergistically to reduce rat brain dopamine content in vitro. Environmental Health Perspectives 1999;107(11):879-885. |
R825812 (1999) R829390 (2005) R829390 (Final) |
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Bemis JC, Seegal RF. Polychlorinated biphenyls and methylmercury alter intracellular calcium concentrations in rat cerebellar granule cells. NeuroToxicology 2000;21(6):1123-1134. |
R825812 (1999) R829390 (2005) R829390 (Final) |
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Bemis JC, Seegal RF. PCB-induced inhibition of the vesicular monoamine transporter predicts reductions in synaptosomal dopamine content. Toxicological Sciences 2004;80(2):288-295. |
R825812 (1999) R829390 (2005) R829390 (Final) R829390C004 (2004) |
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Seegal RF, Pappas BA, Park GAS. Neurochemical effects of consumption of Great Lakes salmon by rats. Regulatory Toxicology and Pharmacology 1998;27(1):S68-S75. |
R825812 (1998) R825812 (1999) |
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Widholm JJ, Clarkson GB, Strupp BJ, Crofton KM, Seegal RF, Schantz SL. Spatial reversal learning in Aroclor 1254-exposed rats: sex-specific deficits in associative ability and inhibitory control. Toxicology and Applied Pharmacology 2001;174(2):188-198. |
R825812 (1999) |
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Supplemental Keywords:
complex mixtures, contaminated Great Lakes fish, solvent extraction and fractionation, polychlorinated biphenyls, PCBs, pesticides, heavy metals, human cognitive dysfunctions, neurobehavior and neurochemical alterations, mechanisms of toxicity, human health., RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Toxics, Geographic Area, Waste, Ecology, Toxicology, Environmental Chemistry, Chemistry, pesticides, chemical mixtures, Risk Assessments, Susceptibility/Sensitive Population/Genetic Susceptibility, Physical Processes, Children's Health, genetic susceptability, Biology, Great Lakes, health effects, pesticide exposure, sensitive populations, dioxin, fish borne toxicant, adolescents, health risks, mothers, Great Lakes salmon consumption, prenatal exposure, exposure, lead, polychlorinated biphenyl, animal model, developmental effects, perinatal exposure, developmental toxicity, children, environmental mutagens, Human Health Risk Assessment, polychlorinated dibenzofuran, neuropsychological, furans, human exposure, behavioral deficits, growth and development, environmental toxicant, pregnant women, perinatanl exposure, arsenic exposure, biological markers, dietary exposure, pregnancy, arsenic, developmental disorders, dioxin exposure, fish-borne toxicants, heavy metals, synergistic interactions, biomarker, Lake OntarioProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.