Date Approved

8-3-2023

Graduate Degree Type

Thesis

Degree Name

Health Sciences (M.H.S.)

Degree Program

Biomedical Sciences

First Advisor

Dr. Christopher Pearl

Second Advisor

Dr. Daniel Bergman

Third Advisor

Dr. Kathryn Haley

Academic Year

2022/2023

Abstract

Increases in infertility over the past 50 years are linked to environmental exposures to endocrine disrupting chemicals (EDCs). One type of EDC is phytoestrogens, commonly found in soy-based diets and foods such as cauliflower, tofu, and broccoli. Phytoestrogens may bind estrogen receptors and have positive or negative effects on receptor signaling. The developing male reproductive tract is potentially susceptible to endocrine disruptors leading to changes in adult reproductive function and possibly infertility. We hypothesized that dietary phytoestrogen exposure would have a dose dependent effect with the high diet yielding the lowest sperm count and worst performance compared to the medium and low phytoestrogen diet. Male C57 mice were fed a diet containing a low, medium or high concentration of phytoestrogens during pubertal development. Testicular and epididymal sperm were counted to determine sperm production and transit times. Differences between the groups were determined by ANOVA using GraphPad Prism statistical analysis software. Daily sperm production (DSP) was not significantly different between groups, however DSP in the high diet group appeared to trend lower. Serum follicle stimulating hormone (FSH) was lowest in the high group indicating changes in pituitary hormone function. Intratesticular testosterone concentration was significantly increased in the high group, indicating a direct effect on the testis. Epididymis weight was increased in the high group suggesting changes in tissue development. Caudal transit time was the longest in the high group, a factor that could negatively affect sperm development. These results suggest that high levels of dietary phytoestrogens may alter pubertal development and sexual maturation in mice.

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