P-045 Effects of seminal BPA levels on human sperm parameters and gene expression

Abstract Study question Are high BPA levels in human seminal fluid associated with low sperm metrics and changes in gene expression? Summary answer A trend towards an inverse relationship between seminal BPA and sperm count was observed. Expression of androgen receptor mRNA was down-regulated with high BPA exposure. What is known already Bisphenol A (BPA) is a widespread industrial chemical, used as the key monomer of polycarbonate plastics and epoxy resins. While some countries have introduced bans/stringent regulation for BPA, it continues to be widely used especially in North America, where its use is only limited in baby products. BPA has been detected in human seminal fluid and has been correlated with decreased sperm counts and motility - crucial factors in determining male fertility, which continue to decrease. We have demonstrated that in vitro BPA exposure can reduce motility, mitochondrial membrane potential, and capacitation in mature bovine spermatozoa. Study design, size, duration In collaboration with CCRM, Toronto, seminal fluid samples were collected from 90 patients undergoing fertility assessment between 2021 and 2023. Typical evaluations such as sperm counts, motility, and morphology were recorded by the clinic (following WHO guidelines). Samples were then shipped to the University of Guelph for further investigations. Information on outcomes for patients who underwent subsequent IVF cycles like fertilization rates and pregnancy rates were also recorded at the clinic. Participants/materials, setting, methods At the University of Guelph, seminal BPA levels were measured through an enzyme-linked immunosorbent assay (ELISA; My BioSource), then compared to sperm metrics obtained by the clinic. Next, a GeNorm analysis was performed to determine the most stable reference genes for subsequent qPCR analysis. The relative mRNA expression of three key genes related to male reproduction (androgen receptor (AR), cyp17a1 and cyp11a1) were quantified and compared between groups with high and low BPA content. Main results and the role of chance BPA concentrations in the seminal fluid samples ranged between 0-3000 pg/mL, with most samples containing 35-1000 pg/mL. When samples were graphed according to increasing BPA levels, no relationships were observed between BPA and motility or morphology rates. However, a negative trend between BPA and sperm count was detected, although this was not significant. Samples were then divided into high- (total 15 sampl