The Effects of Cadmium Exposure on Biochemical Indexes, Antioxidant Responses, Inflammation, and Anti-Stress Responses of Juvenile GIFT Tilapia (Oreochromis niloticus).

Abstract

This study investigated the effects of cadmium (Cd2+) exposure on the biochemical indexes, antioxidant responses, non-specific immune responses, inflammatory responses, anti-stress responses, and related gene expression levels of juvenile GIFT tilapia (Oreochromis niloticus). Four groups of juveniles were cultured for 30 days in four aquaculture waters with different levels of Cd2+ concentrations (0, 0.2, 0.4, and 0.6 mg/L). Key findings include: In comparison to the control group (0 mg/L Cd2+), cadmium stress significantly impacted the liver and serum biochemical indices of juvenile tilapia (p < 0.05). The activities of catalase (CAT), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) in the gills, liver, and serum were significantly decreased (p < 0.05) and the contents of malondialdehyde (MDA) showed the opposite trend. The expression levels of interleukin-10 (IL-10), sonic hedgehog (SHH), and cytochrome oxidase 1A (CYP1A) were significantly down-regulated (p < 0.05) and the expression levels of interleukin-1β (IL-1β), tumor necrosis factor α (TNFα), interferon γ (IFNγ), interleukin-6 (IL-6), interleukin-8 (IL-8), transforming growth factor β1 (TGF-β1), metallothionein (MT), and heat shock protein 70 (HSP70) in the liver were significantly up-regulated (p < 0.05). In conclusion, the concentration of cadmium in aquaculture water exceeded 0.2 mg/L, and the biochemical indexes, antioxidant responses, non-specific immune responses, inflammatory responses, and anti-stress responses of juvenile GIFT tilapia were markedly altered. These findings highlight that even sub-lethal Cd2+ concentrations (≥ 0.2 mg/L) pose substantial risks to the physiological health and survival of juvenile tilapia.