# Acute Exposure to a Common Organic UV Filter Does Not Alter the mRNA of Gonadal Estrogen or Growth Hormone Receptors in Mozambique Tilapia (Oreochromis mossambicus) In Vitro

## TL;DR

This study finds that a common UV filter does not change gene activity in fish gonads after short-term exposure.

## Contribution

The first in vitro study on BP-3's effects on fish gonadal gene expression using environmentally relevant doses.

## Key findings

- BP-3 does not alter mRNA levels of estrogen or growth hormone receptors in tilapia gonads after 24 hours.
- ERβ regulation in male tilapia gonads is confirmed, similar to other fish species.

## Abstract

Background/Objectives: Organic UV filters are chemical compounds that are commonly used in sunscreen products to absorb UV radiation from the Sun. To date, the filters have been detected in aquatic environments worldwide, as well as in aquatic organisms, including fish and coral. Hydroxy-4-methoxybenzophenone (BP-3) is a common organic UV filter and it is well documented to be among the filters that are detectable worldwide in water samples and aquatic organisms. Long-term exposure in vivo studies have demonstrated that high doses of BP-3 can cause endocrine-disrupting effects in aquatic organisms. Methods: Using gonadal cell culture and quantitative RT-PCR, our study aimed to ascertain the effect of environmentally relevant doses of BP-3 (detected in aquatic systems) on the gene expression of reproductive targets, estrogen and growth hormone receptors (ERs and GHRs), in Mozambique tilapia (Oreochromis mossambicus) after an acute 24 h treatment. Results/Conclusions: Our study is the first to use an in vitro design to investigate the mechanism of the action of BP-3 on gonadal tissue in fish. Our results show that BP-3 does not induce gene regulation directly on the gonads of tilapia at doses that are comparable to what is detectable in aquatic environments after 24 h. We do verify, as seen in other teleost species, homologous regulation of ERβ in male tilapia gonadal tissue.