Chronic exposure to tralopyril induced abnormal growth and calcium regulation of turbot (Scophthalmus maximus)

Tralopyril is an emerging marine antifouling agent with limited data on its effects on fish growth and calcium regulation. To determine the changes induced by long-term exposure to tralopyril, multi-levels (such as molecular, biochemical, and individual levels) responses were measured in turbot at different concentrations (1 μg/L, 20 μg/L). The results showed that 1 μg/L mainly affected the immune response, while 20 μg/L affected the synthesis and metabolism of steroids and fat. However, different concentrations of tralopyril affected the synthesis, secretion and action of parathyroid hormone and growth hormone. The expression of GH/IGF axis gene and the level of growth hormone increased significantly, leading to abnormal growth. The energy tradeoff between immunity and growth at 1 μg/L tralopyril pressure may inhibit growth. The change of Ca2+ level was accompanied by the disturbance of PTH-related gene expression. The results of molecular docking showed that the disturbance of Ca2+ regulation might be attributed to the inhibition of vitamin D receptor by tralopyril, which affected the vitamin D signaling pathway. This study provides scientific data for the in-depth understanding and risk assessment of the toxicological effects of tralopyril and reveals the potential threat of tralopyril to environmental health.