Different environmental chemicals can affect the reproductive capability of a variety of organisms, depending on the timing and dose of exposure, and are thought to impact human reproduction as well. One example is the phytoestrogen, genistein, which when given to neonatal female mice has long-term effects on their ability to reproduce. The underlying causes of their infertility, however, are not known. A second example is diethylstilbestrol, which causes reproductive tract malformations when given prenatally (before birth) and reproductive tract dysfunction and cancer when given neonatally (around the time of birth). We are using both neonatal genistein and DES treatments to determine how estrogenic compounds affect female reproductive tract development and function, and how these compounds influence embryo development within the female reproductive tract through the time of implantation. These studies are relevant to human fertility because genistein levels similar to those reached in our mouse model are measured in babies on soy-based infant formula, and many other estrogenic compounds are found in the environment and could affect reproductive tract development and function. Female mice treated neonatally with the phytoestrogen genistein are infertile because of deficiencies in embryo development in the oviduct and defects in implantation. During the past year we performed a series of experiments to characterize the abnormalities in the oviduct. We found significant alterations in morphology and permanently altered patterns of gene expression of inflammatory response factors known to modulate female reproductive tract function. We also found that the abnormal oviduct environment causes abnormalities in blastocyst development that are likely a consequence of alterations in the oviduct mucosal immune response to pregnancy;however, these abnormalities do not preclude successful term development after embryo transfer. These studies were published in Biology of Reproduction. We also found that neonatal genistein exposure to female mouse pups causes hypospadias, an abnormality of the urethral opening in the external genitalia;this finding was published in Molecular Reproduction &Development. We are continuing studies to determine the epigenetic mechanisms underlying the effects of both genistein and DES on female reproductive tract function. There is evidence in rodents that prenatal exposure to environmentally relevant doses of bisphenol A (BPA) causes abnormal ovarian and female reproductive tract development. Although the rodent studies have raised concerns regarding human exposure to BPA, there is minimal information regarding the effects of BPA on development in humans or non-human primate models. Dr. Patricia Hunt (Washington State Univ.) and Dr. Cathy VandeVoort (UC Davis Primate Center) initiated a study to examine the effects of maternal BPA exposure during either the 2nd or 3rd trimesters of pregnancy on development of female Rhesus monkey fetuses. The monkeys were treated using 2 different BPA dosing strategies, and all tissues have been collected. We are finalizing our evaluation of the morphology and gene expression in the female reproductive tract. This project will generate a gene expression profile of developing normal Rhesus monkey oviduct and uterus, and also provide evidence regarding whether there are differences in the gene expression profiles and histology when comparing control and BPA-treated groups.
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