Toxicological effects of nodularin on the reproductive endocrine system of female zebrafish (Danio rerio)

• Published in: Aquatic toxicology Vol. 273; p. 107000
• Main Authors: Biswas, Chayan, Adhikari, Madhuchhanda, Pramanick, Kousik
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.08.2024
• Subjects: Algal bloom; Cyanotoxin; Endocrine disruption; Eutrophication; Reproductive toxicity; Endocrine disruption; Algal bloom; Reproductive toxicity; Cyanotoxin; Eutrophication
• ISSN: 0166-445X; 1879-1514; 1879-1514
• DOI: 10.1016/j.aquatox.2024.107000

•Nodularin causes endocrine disruption by decreasing gonadotropin levels (FSH and LH) and E2/T ratio.•Nodularin disrupts oocyte growth in female zebrafish by inhibiting vitellogenesis in the liver.•Nodularin inhibits oocyte maturation and alters gene expression patterns on the HPGL axis of female zebrafish.•Nodularin induces oxidative stress in the brain, ovary, and liver of female zebrafish. Nodularin is a potent cyanotoxin that has been detected in aquatic environments as well as in the body of aquatic organisms throughout the world, but its effects on the reproductive system are yet to be explored. The present study investigated the toxic effects of environmentally relevant concentrations of nodularin on the reproductive endocrine system of female zebrafish (Danio rerio). After exposure to nodularin for 14 days, decreased gonadosomatic Index (GSI), germinal vesicle breakdown (GVBD), and decreased level of follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17β-estradiol (E2) level and increased testosterone (T) content in female zebrafish suggested that nodularin may disrupt both oocyte growth and maturation. In support of this data, alteration in different marker gene expression on the hypothalamic-pituitary-gonadal-liver (HPGL) axis was observed. Transcriptional levels of genes related to steroidogenesis including cytochrome P450 aromatase (cyp19a1a) in the ovary and primary vitellogenin genes (vtg1, vtg2, and vtg3) in the liver were down-regulated and marker genes for oxidative stress (sod, cat, and gpx) were up-regulated on HPGL axis. These findings revealed for the first time that nodularin is a potent endocrine-disrupting compound posing oxidative stress and causes reproductive endocrine toxicity in female zebrafish, emphasizing the importance of assessing its environmental risks.