Toxic effects of paraquat on cytokine expression in common carp, Cyprinus carpio L

In this study, the acute toxicity of paraquat (PQ) in common carp was determined. Then, the contents and mRNA levels of the cytokines interleukin-1β (IL-1β), interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) were evaluated following subacute exposure to PQ. The results show that the LC50 of PQ for common carp at 72 and 96 h was 15.962 and 15.106 mg/L, respectively. Moreover, after 7 days of subacute PQ exposure, the IL-1β content in the fish liver and kidney increased, although it decreased in spleen. However, changes in the IFN-γ content showed an irregular trend. The TNF-α content increased in the liver and spleen but decreased in the kidney. Additionally, PQ exposure also induced alterations in the mRNA levels of IL-1β, IFN-γ, and TNF-α. These results suggest that PQ exposure may result in suppression or excessive activation of the immune system in treated fish and lead to immune dysfunction and reduced immunity.