Dietary parsley seed powder attenuates acrylamide-waterborne toxicity hazards on growth, redox status, immunity and gene regulations in Oreochromis niloticus.

Abstract

This study evaluated the protective role of dietary parsley seed powder (PSP) against acrylamide (ACR) toxicity in Nile tilapia (Oreochromis niloticus). A total of 200 juvenile fish (15.98 ± 0.01 g) were randomly assigned to four dietary groups (0.0, 2.5, 5.0 and 10.0 g PSP/kg diet) and exposed for 56 days to a sublethal ACR concentration (3.46 mg/L). Throughout the experiment, growth performance, blood biochemical indices, immune responses, oxidative stress biomarkers, digestive enzyme activities, histopathology and hepatic gene expression were thoroughly assessed. The results revealed that PSP supplementation, particularly at 10.0 g/kg, significantly improved final body weight, body weight gained, daily weight gain and survival rate (p ≤ 0.05), while reducing feed conversion ratio significantly at 2.5 g/kg (p ≤ 0.001). Moreover, blood AST activity was significantly decreased in the 5.0 and 10.0 g/kg groups (p ≤ 0.01), accompanied by significantly elevated total protein and albumin (p < 0.01), and reduced uric acid and creatinine levels (p ≤ 0.001), indicating hepatoprotective and nephroprotective effects. Additionally, PSP exerted anti-inflammatory and antioxidant benefits, as evidenced by significantly reduced serum tumour necrosis factor-α (TNF-α) levels (p ≤ 0.001) and increased glutathione (GSH) concentration (p ≤ 0.05), especially in the 10.0 g/kg group. Digestive enzymes (amylase and pepsin) exhibited a significant increase at all PSP levels (p ≤ 0.05 or 0.01), with the highest levels observed in the DP3 group (10.0 g PSP/kg diet). Histopathological evaluation indicated a dose-dependent attenuation of intestinal and hepatopancreatic alterations with increasing PSP levels, as evidenced by reduced lesion severity, decreased necrotic changes and better preservation of tissue architecture. Furthermore, gene expression analysis revealed significant downregulation of cysteine-aspartic acid protease-3 (caspase-3) and tumour necrosis factor-alpha 2 (tnf-2α) genes (p ≤ 0.01) and upregulation of insulin-like growth factor 1 (igf-1) and growth hormone (gh) (p ≤ 0.01) genes in the 10.0 g/kg group, indicating enhanced growth and cellular resilience. In conclusion, dietary PSP at 10.0 g/kg significantly alleviates ACR toxicity by enhancing physiological, biochemical, immunological and molecular responses in Nile tilapia.