Effects of exposure to atrazine on retinoid signaling in zebrafish

Atrazine is a widely used herbicide developed for use in range and pastureland. It is present in many surface waters, contaminating nontarget organisms due to its persistence. In this study, the effects of acute exposure to atrazine on retinoid signaling were investigated in zebrafish. Zebrafish embryos were exposed to atrazine from 6 hours post-fertilization (hpf) to 120 hpf. The contents of retinal and retinoic acid were decreased significantly. The mRNA expression levels of retinal dehydrogenase ( raldh2 ), retinol dehydrogenase ( rdh1 ), retinol binding protein ( rbp1a ), retinoic acid receptor subunit ( raraa ), and cellular retinoic acid binding protein ( crabp1a and crabp2a ) were significantly reduced, which indicated that retinoid signaling was interrupted. However, the transcriptional levels of five opsin genes ( zfrho , zfuv , zfred , zfblue , and zfgr1 ) were increased. These results indicated that exposure to atrazine could inhibit retinoid signaling and impair the eye development of zebrafish larvae.