Antidepressants as new endocrine disruptors? – transcriptomic profiling in gonads of Mytilus trossulus exposed to norfluoxetine

In this study an impact of norfluoxetine (NFLU) on Mytilus trossulus gonads was investigated focusing on sex-related differences in hormonal changes, gene expression, and transcriptomic profiling. Sex-specific differences in gonadal serotonin levels were found. NFLU stimulates serotonin synthesis and/or transport in female gonads, potentially accelerating oocyte maturation and gamete release. In males, NFLU decreases serotonin level what likely leads to impeding sperm maturation and thus spawning delay. Transcriptomic analyses highlighted the presence of NFLU-induced changes in gene expression related to gametogenesis and neurotransmission. In females, NFLU upregulated genes associated with oocyte development and downregulated those involved in sperm maturation. NFLU-treated males exhibited mixed effects in their genes in relation to spermatogenesis. Additionally, sex-related differences in the expression of the CYP450 genes responsible for detoxification were found. Overall, norfluoxetine acts as an endocrine-disrupting chemical and impacts gonadal serotonin levels and gene expression, potentially disrupting reproductive success of M. trossulus.