Silver nanoparticles modify the hypothalamic–pituitary–interrenal axis and block cortisol response to an acute stress in zebrafish, Danio rerio

• Published in: Toxicology and industrial health 2022-04, Vol.38 (4), p.201-209
• Main Authors: Arab-Bafrani, Zahra, Zabihi, Erfan, Hoseini, Seyyed Morteza, Sepehri, Hamid, Khalili, Mohsen
• Format: Article
• Language: English
• Subjects: Air exposure; Animals; Brain; Corticotropin-releasing hormone; Corticotropin-Releasing Hormone - genetics; Corticotropin-Releasing Hormone - metabolism; Cytochrome; Cytochrome P-450 Enzyme System; Cytochrome P450; Cytochromes P450; Danio rerio; Down-regulation; Exposure; Gene expression; Genes; Hormones; Hydrocortisone - metabolism; Hypothalamus; Kidneys; Melanocortin; Metal Nanoparticles - toxicity; Nanoparticles; Pituitary; Pro-Opiomelanocortin - genetics; Pro-Opiomelanocortin - metabolism; Proopiomelanocortin; Proprotein convertases; Receptor, Melanocortin, Type 2 - genetics; Receptor, Melanocortin, Type 2 - metabolism; Receptors; Silver; Silver - toxicity; Steroidogenic acute regulatory protein; Stress, Physiological; Transcriptomics; Zebrafish; Zebrafish - genetics
• ISSN: 0748-2337; 1477-0393
• DOI: 10.1177/07482337221086128

The present study aimed at assessing the effects of exposure to silver nanoparticle (AgNP) and a subsequent acute stress on the expression of various genes involved in the hypothalamus–pituitary–interrenal (HPI) axis in zebrafish, Danio rerio. The fish were exposed to 0 (Control), 0.1 (LC), 0.4 (MC), and 1.2 (HC) mg Ag/L (as AgNP) over a 2-week period, followed by an acute air exposure stress. The whole body cortisol and the expression of selected genes in the fish brain and kidney were analyzed, before and after the acute stress. The results showed that AgNP increased basal cortisol levels and the expression of corticotropin releasing factor, prohormone convertase 1, pro-opiomelanocortin, and melanocortin 2 receptor; however, it suppressed/inhibited whole body cortisol, brain corticotropin releasing factor responses, pro-opiomelanocortin, and the kidney melanocortin 2 receptor responses to the acute stress. AgNP down-regulated the expression of the steroidogenic acute regulatory protein, but it intensified the gene expression in response to the acute stress. Before the acute stress, LC treatment exhibited an up-regulation in Cytochrome P450-11A-1 expression, but MC and HC treatments induced down-regulation. After the acute stress, the AgNP-exposed fish exhibited decreased Cytochrome P450-11A-1 expressions, compared with the Control. Exposure to AgNP significantly increased Cytochrome P450-11B expression. However, after the acute stress, LC treatment exhibited an up-regulation, but MC and HC treatments exhibited down-regulation in the Cytochrome P450-11B gene expression. In conclusion, AgNP suppressed cortisol response to stress, which appears to be a consequence of alterations in the HPI axis at the transcriptomic levels.