Zarei_2025_J.Hazard.Mater_501_140956

Aquatic ecosystems are increasingly threatened by organophosphate pesticides (OPPs) such as diazinon (DZN) and polycyclic aromatic hydrocarbons (PAHs) like benzo[a]pyrene (BaP), both of which disrupt metabolic, immune, and neural functions in fish. This study investigated the protective efficacy of Spirulina platensis (SP), a natural heat shock protein inducer (HSPi), against DZN- and BaP-induced toxicity in Acipenser stellatus fingerlings. Experimental treatments involved individual and combined exposures to DZN and BaP, with or without SP supplementation, over 1, 3, and 6 days. Gas chromatography-mass spectrometry (GC-MS) analysis identified methyl palmitate (38.43 %) and gamma-linolenic acid methyl ester (GLA; 19.06 %) as the predominant bioactive constituents of SP. Exposure to DZN and BaP significantly increased hepatic cytochrome P450 (CYP450; up to 0.95 ng/mg protein), serum cortisol (to 33 ng/mL), and liver enzyme activities, while reducing acetylcholinesterase (AChE) activity by approximately 40 %. In contrast, treatments combining SP with pollutant stress markedly upregulated HSP70 expression, enhanced antioxidant enzyme activities, and elevated immune markers by 25-40 %. Furthermore, SP supplementation reduced cortisol levels by 30-35 % and restored AChE activity to near-baseline values. These findings demonstrate SP's HSP70-mediated cytoprotective effects and support its potential as a dietary strategy to mitigate multi-pollutant stress in aquatic organisms.