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چکیده
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Silver nanoparticles (AgNPs) are extensively used in consumer products due to their antimicrobial properties, leading to their release into aquatic environments. There is growing evidence that the biological effects of AgNPs in aquatic organisms can be modulated by nutritional and metabolic factors. This study investigated how variations in dietary energy availability modulate the physiological and toxicological responses to AgNPs exposure in zebrafish (Danio rerio). Six dietary treatments were tested for 28 days, combining three feeding regimens—restricted (RC), normal (NC), and high-calorie (HC)—with or without 50 mg kg⁻¹ AgNPs supplementation (RC+AgNPs, NC+AgNPs, HC+AgNPs). Growth performance and metabolic indices revealed that high-calorie feeding enhanced body weight and specific growth rate, whereas co-exposure to AgNPs significantly altered blood glucose and whole-body lipid status in a diet-dependent manner. In contrast, caloric restriction attenuated AgNPs-induced hyperglycemia and lipid-related accumulation. AgNPs exposure disrupted antioxidant defense, reducing SOD and CAT activities and altering GPx activity, accompanied by increased malondialdehyde (MDA) levels, with the strongest oxidative imbalance observed in the HC+AgNPs group. Fatty acid profiling revealed diet-dependent increases in MUFA and decreased PUFA and HUFA fractions following AgNPs exposure, accompanied by altered n-6 and n-3 PUFA proportions and an increased n-6/n-3 ratio. Whole-body silver concentrations were highest in HC+AgNPs, whereas RC+AgNPs exhibited the lowest metal retention, coinciding with more stable Cu, Zn, and Fe levels. Collectively, these results demonstrate that dietary energy availability strongly modulates AgNPs toxicity: excessive caloric intake amplifies oxidative and metabolic disruption, whereas caloric restriction confers partial protection by maintaining redox and metabolic homeostasis. Integrating nutritional context into nanotoxicological assessments is therefore essential for realistic ecological risk evaluation.
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