P-067 Correlation between Zn/Cu ratio and Bisphenol A in seminal plasma in men with varicocele
Authors: Jeseta M , Navrátilová J , Franzová K , Kalina J , Fialková S , Mekiňová L , Žáková J , Ventruba P , Crha I 
Published: June 2022

Abstract

Study question
Is there a relationship between concentration of Bisphenol A (BPA), Zn contents and Zn/Cu ratio in seminal fluid and spermiogram parameters in men with varicocele?

Summary answer
Our results document correlations between BPA, Zn/Cu and sperm motility. We found that the negative effect of BPA can be attenuated by higher Zn/Cu levels.

What is known already
A range of environmental factors including organic endocrine disruptors affects spermatogenesis. Bisphenols are endocrine disruptors often used in production of plastics. BPA is an endocrine disruptor with negative effects on reproduction. Presence of BPA also induces production of reactive oxygen species with negative impact on spermatogenesis. Zinc and copper are trace elements important for human spermatogenesis. Zn and especially the ratio of Zn/Cu are good parameters of the antioxidant potential of seminal plasma. The relationship between BPA levels, Zn concentration and Zn/Cu ratio with human sperm parameters is still unclear.

Study design, size, duration
In this study, we evaluated correlation between BPA concentration, Zn concentration and ratio of Zn/Cu in seminal plasma in relation to sperm concentration, number of spermatozoa, total motility, progressive motility, morphology and DNA fragmentation. A total of 123 nonsmoking patients aged 18 - 45 (average 28) years with varicocele were included in this prospective study from 2019 to 2021.

Participants/materials, setting, methods
All the men signed an informed consent and agreed with analyses. Ethical Committee of University Hospital Brno approved analyses. Seminal plasma was collected after centrifugation. BPA was determined by the LC-MS/MS method (liquid chromatography-tandem mass spectrometry). The concentrations of Zn and Cu were measured by inductively coupled plasma mass spectrometry (Agilent 8900 ICP-MS/MS). Statistical evaluation was performed using Spearmen test (p = 0.05). The relationship between parameters was expressed by Spearman's correlation coefficient (ρ).

Main results and the role of chance
Analytical examination of seminal fluids detected presence of BPA in 89 samples (72.3 % of all samples analysed with average value 0.1627 ng/ml). In 18 samples, the concentration was under the level of detection and in 16 samples under the level of quantification. Zn was detected in all 123 patients with average concentration 139.44 µg/ml. The Zn/Cu ratio was calculated with average value 1.73. Subsequently, individual parameters of spermiogram plus DNA integrity were assessed. In case of BPA, negative correlations were found between BPA concentration and total motility (p = 0.010) and progressive motility (p = 0.012). Similarly, positive significant correlations between Zn/Cu ratio and total motility (p = 0.032) and progressive motility (p = 0.028) were found. For Zn concentration, we found positive non-significant correlation with total motility (p = 0.144) or progressive motility (p = 0.147). There were non-significant correlations between the BPA, Zn/Cu ratio or Zn and other parameters. Similarly, for BPA and Zn/Cu ratio a non-significant positive correlation was found (p = 0.157) and neither significant correlation was found between BPA and Zn (p = 0.452). In several cases we observed normal progressive and total motility in patients with high BPA concentrations together with high Zn/Cu ratio which probably has a protecting effect from the high BPA levels.

Limitations, reasons for caution
A limitation for this study is the final number of patients analysed in this study, which slightly reduced the power of statistical analysis. Currently, more analyses focused on detection of BPA in seminal plasma are being carried out in order to obtain sufficiently larger data set.

Wider implications of the findings
In this study, BPA was detected in 72 % of analysed samples. Our first results indicate a higher sensitivity of spermatozoa to BPA presence in seminal fluid, affecting mainly their motility. Interestingly, a higher Zn/Cu ratio is potent to reduce partially the negative impact of BPA on human spermatozoa.

Trial registration number
Supported by Czech Health Research Council (NV18-01-00544 and NV18-08-00291) and MH CZ – DRO (FNBr, 65269705). Jana Navratilova was supported by the Czech Ministry of Education, Youth and Sports (CZ.02.2.69/0.0/0.0/19_074/0012727). Authors also thanks to Research Infrastructure RECETOX RI (No LM2018121) financed by the Ministry of Education, Youth and Sports, and Operational Programme Research, Development and Innovation - project CETOCOEN EXCELLENCE (No CZ.02.1.01/0.0/0.0/17_043/0009632) for supportive background.