Parental Bisphenol S exposure induces oxidative stress and disrupts serotonergic and cholinergic neurotransmission in zebrafish offspring

Bisphenol S (BPS), a structural analogue of bisphenol A (BPA), is widely used in consumer products and increasingly detected in aquatic environments, raising concerns about its long-term ecological and health impacts. Although short-term developmental neurotoxicity of BPS has been documented, its potential intergenerational effects remain largely unknown. In this study, zebrafish (F 0 ) embryos were exposed to an environmentally relevant concentration of BPS (30 µg/L) from 4 to 120 h post-fertilization (hpf) and subsequently reared in clean water until adulthood (6 months). Adult fish were then crossed to generate F 1 offspring through maternal, paternal, and parental lineages, which were assessed for behavioural and molecular endpoints. Although hatching success, survival, and behaviour remained unaffected across maternal, paternal, and parental lineages, distinct lineage-specific molecular alterations were observed. All lineages exhibited increased reactive oxygen species, lipid peroxidation, and neuronal apoptosis, accompanied by suppression of gpx1a and mn-sod and induction of creb1a , indicating persistent oxidative stress and apoptotic activation. The serotonergic pathway showed marked vulnerability, with downregulation of htr1aa , htr2a , and slc6a4a and elevated serotonin levels, particularly in the parental lineage. Cholinergic signalling was similarly affected, as chata and slc18a3a were upregulated while acetylcholine concentrations increased, suggesting cholinergic hyperactivity. Neurotrophic markers revealed bdnf upregulation and manf downregulation, implying impaired neuronal maintenance and endoplasmic-reticulum stress. Lineage comparisons revealed that the maternal BPS lineage primarily exhibited alterations in serotonergic and cholinergic signalling, whereas the paternal BPS lineage showed stronger oxidative and neurotrophic disruption, and the parental BPS lineage exhibited both, representing the most comprehensive molecular perturbation. These results demonstrate that parental exposure to environmentally relevant BPS concentration induces stable, lineage-specific transcriptional and neurochemical reprogramming without overt phenotypic change. Such latent molecular neurotoxicity highlights the capacity of BPS to silently compromise neurotransmission and stress-response networks across generations, emphasizing the need to include molecular inheritance endpoints in future BPS risk assessments.