Grantee Research Project Results
1997 Progress Report: Altered Sperm-Oocyte Interactions after Exposure to Reproductive Toxicants
EPA Grant Number: R825351Title: Altered Sperm-Oocyte Interactions after Exposure to Reproductive Toxicants
Investigators: Berger, Trish , Miller, Marion G.
Institution: University of California - Davis
EPA Project Officer: Hahn, Intaek
Project Period: December 1, 1996 through November 30, 1999
Project Period Covered by this Report: December 1, 1996 through November 30, 1997
Project Amount: $471,954
RFA: Exploratory Research - Environmental Biology (1996) RFA Text | Recipients Lists
Research Category: Biology/Life Sciences , Aquatic Ecosystems
Objective:
The objectives of this study are to evaluate sperm-oocyte interaction for assay sensitivity of sperm and oocytes to reproductive toxicants compared with sensitivity of assays analyzing sperm motility, spermatogenesis, and epididymal function and to evaluate the sperm and oocyte plasma membrane proteins including those that specifically interact with the complementary gamete surface as potentially more sensitive markers of exposure to toxicants and as part of the explanation for the effect of the toxicants.Progress Summary:
The sensitivity of the male reproductive system to toxicant exposure assessed by sperm fertilizing potential in an in vitro fertilization system is being compared with computer assisted analysis of sperm motility and sperm morphology. For example, male rats were exposed to 2000 ppm perchloroethylene in air for 1 or 2 hours daily while located in exposure chambers. Control animals were placed in exposure chambers and breathed room air. Epididymal sperm were obtained from males exposed for 2 or 3 weeks (5 days per week) and evaluated for fertilizing ability in an in vitro fertilization assay and for sperm motion parameters using a Hobson sperm tracker. Sperm from males exposed to the perchloroethylene during two 1-hour periods per day had reduced fertilizing ability (P < 0.05) compared with the control rats placed in the exposure chambers for two 1-hour periods. Sperm from these same groups of rats exhibited some differences between control and treated groups in two parameters of sperm motion, amplitude of lateral head displacement and linearity. Since control males loaded in exposure chambers twice per day had an apparent but nonsignificant reduction in fertilizing ability compared with control males loaded in exposure chambers once per day, we are evaluating exposures via drinking water prior to extending exposures to longer term.Sperm plasma membranes have been isolated from rats exposed to dinitrobenzene, ethylene glycol monomethyl ether, perchloroethylene, and from control rats. Differences in protein composition are apparent in the initial samples separated by SDS PAGE.
The sensitivity of the female reproductive system to toxicant exposure is being assessed by the fertilizability of oocytes in an in vitro fertilization system. For example, young female rats were exposed twice per day to 2000 ppm perchloroethylene for two weeks (5 days per week) prior to oocyte recovery. The fertilizability of the zona-free oocytes from perchloroethylene- exposed females was slightly but significantly reduced (P < 0.01) compared with control females exposed to room air in the exposure chambers.
Our current work suggests that the in vitro fertilization bioassay is a more sensitive assessment of toxicant exposure than more routine assays for some reproductive toxicants.
Future Activities:
Sperm plasma membranes isolated from treated and control male rats will be analyzed for the relative amounts of specific proteins with an affinity for the oocyte plasma membrane. The binding of sperm plasma membrane proteins to the oocyte surface will also be assessed both as a means to further understand the effect of the toxicants and as a potential biomarker for toxicants affecting female gametes. Anticipated alterations in plasma membrane proteins interacting with the complementary gamete are expected to contribute to the mechanism of the toxicant effect. This research is expected may lead to more sensitive biomarkers of reproductive toxicant effects in both the male and female.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 2 publications | 1 publications in selected types | All 1 journal articles |
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Jelks K, Berger T, Horner C, Miller MG. α-Chlorohydrin induced changes in sperm fertilizing ability in the rat: association with diminished sperm ATP levels and motility. Reproductive Toxicology 2000;15(1):11-20. |
R825351 (1997) |
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Supplemental Keywords:
mammalian, cellular, chemicals, measurement methods,, Health, Scientific Discipline, Environmental Chemistry, Chemistry, Epidemiology, Risk Assessments, Biology, ecological risk assessment, sperm plazma membranes, toxicology, sperm-oocyte interactions, toxic environmental contaminants, spermatogenesis, gametes, biomarker, in vitro fertilizationProgress 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.