Sex-specific reproductive toxicity of subacute exposure to glufosinate-ammonium in zebrafish (Danio rerio).

Glufosinate-ammonium (GLA) is a common agricultural herbicide used worldwide. It can be transported into water bodies and can persist for long periods, posing a risk to non-target aquatic organisms. In this study, adult zebrafish were exposed to GLA (0, 0.6, 6, and 60 mg/L) for 21 days to evaluate its effect on reproduction. Fecundity, offspring development, sex hormone levels, histological changes, and apoptosis in the gonads were measured, and the expression levels of genes related to the hypothalamic-pituitary-gonadal-liver (HPG-L) axis, the cell cycle, and apoptosis were examined to assess the toxic mechanisms of GLA. Higher GLA concentrations were measured in the ovaries than in the testes. Decreases in spawning count, sperm density, and motility were observed. Meanwhile, the offspring survival rate decreased, and larval offspring swimming behavior was inhibited. GLA exposure significantly increased estradiol levels in females and reduced testosterone levels in males by affecting the expression of HPG-L axis genes. Furthermore, GLA exposure induced apoptosis in gonadal cells by controlling the expression of genes involved in cell cycle regulation and apoptotic pathways. Notably, the smaller effects of GLA concentration on body weight, gonad somatic index value, gonadal cell composition, and gonadal cell apoptosis were observed in male fish than in female fish. Taken together, GLA can accumulate in the gonads and cause sex-specific alterations in the expression of genes involved in the HPG-L axis and subsequent steroidogenesis and gametogenesis, which may be responsible for GLA-induced reproductive and developmental toxicities.