Women are exposed daily in the workplace, as well as the environment (cigarette smoke, automobile exhaust) to chemicals that can damage small pre-antral (primordial) ovarian follicles. Damage to these follicles can result in early ovarian failure (menopause). Because menopause is associated with a variety of health disorders, this represents a plausible health risk. Dosing of mice and rats with the occupational chemical, 4-vinyl-cyclohexene diepoxide (VCD) destroys primordial follicles and early ovarian failure can be caused in rodents by repeated dosing. On-going mechanistic studies in rats have helped characterize VCD as a model chemical for the study of xenobiotic-induced destruction of primordial follicles. However, the exact mechanism, which initiates oocyte degeneration, remains unknown. Thus, it is proposed here to expand the base of mechanistic information obtained with VCD to further identify those mechanisms. Because a variety of environmental chemicals are known to destroy primordial follicles, VCD-related information will prove applicable to chemicals that are sources of greater exposure in the environment. Therefore, a comparison between selected parameters of VCD-induced ovotoxicity and another environmental chemical, 9,10-dimethylbeznanthracene, DMBA, present in cigarette smoke and automobile exhaust will also be made. The hypothesis to be tested is that VCD causes destruction of primordial follicles by upregulation of pre- and post-transcriptional intracellular pathways and DMBA initiates similar events.
The Specific Aims are to: 1) identify and characterize gene expression directly regulated by VCD dosing, 2) dissect signaling pathways involved in VCD-induced ovotoxicity 3) compare selected signaling events initiated by DMBA with those of VCD, and 4) characterize the ability of ovarian compartments to bioactivate and detoxify VCH, VCD, and DMBA. Specifically investigating the mechanism(s) by which VCD damages ovarian primordial follicles and comparing this with DMBA will provide a greater ability to predict potential risks for early menopause from environmental exposures in women. This greater awareness will lead to an appreciation of the global impact of the environment on age of menopause in women ? ?
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