Synthetic phenolic antioxidants evoked hepatoxicity in grass carp (Ctenopharyngodon idella) through modulating the ROS-PI3K/mTOR/AKT pathway: Apoptosis-autophagy crosstalk.

Synthetic phenolic antioxidants (SPAs) are an environmental concern due to their persistence nature and bioaccumulation. However, the hepatoxicity and mechanisms of SPAs in aquatic organisms remain poorly understood. In this study, grass carp were exposed to two representative SPAs (BHA and BHT) at environmentally relevant levels (0.1 µM) for 30 days. We observed that BHA and BHT exposure significantly increased the levels of serum aminotransferase (ALT) and aspartate aminotransferase (AST) in grass carp, accompanied by mild inflammatory cell infiltration and irregularity in the shape of hepatocytes. Dihydro ethylenediamine staining showed that BHA and BHT exposure resulted in elevated levels of superoxide levels, accompanied by increased antioxidant enzyme activities (T-AOC, SOD, CAT, GSH-PX) and MDA levels, which is suggestive of oxidative stress responses in the liver of grass carp. Besides, BHA and BHT could dock into the pocket of phosphatidylinositol 3-kinases (PI3K) and thereby inhibiting PI3K/mammalian target of rapamycin (mTOR)/protein kinase B (AKT) signaling cascades. Meanwhile, our results clarified that BHA and BHT could promote autophagosome production and increase the expression of key autophagy proteins, likely due to inhibition of PI3K/mTOR/AKT signaling pathway. Moreover, BHA and BHT could induce apoptotic process by upregulating the expression of Bax, Caspase3 and Caspase8 and downregulating Bcl2 expression. Notably, BHT exhibited more hepatoxicity on the indicators of the apoptosis and oxidative stress than BHA. In summary, our findings demonstrated that BHA and BHT exposure could induce liver damage induced via regulating ROS/PI3K-mediated autophagic hyperactivation, which is a crucial step in triggering hepatocyte death. This study provides novel insight into the potential mechanisms underlying liver damage caused by BHA and BHT in aquatic organisms, and offers a new theoretical basis for ecological risk assessment of SPAs.

Lycopene abolishes typical polyhalogenated carbazoles (PHCZs)-induced hepatic injury in yellow catfish (Pelteobagrus fulvidraco): Involvement of ROS/PI3K-AKT/NF-κB signaling.

Aquatic ecosystems are being more contaminated with polyhalogenated carbazoles (PHCZs), which raising concerns about their impact on aquatic organisms. Lycopene (LYC) exhibits several beneficial properties for fish via enhance antioxidant defenses and improve immunity. In this study, we attempted to investigate the hepatotoxic effects of typical PHCZs 3, 6-dichlorocarbazole (3,6-DCCZ) and the protective mechanisms of LYC. In this study, we found that yellow catfish (Pelteobagrus fulvidraco) exposure to 3,6-DCCZ (1.2 mg/L) resulted in hepatic inflammatory infiltration and disordered hepatocyte arrangement. Besides, we observed that 3,6-DCCZ exposure resulted in hepatic reactive oxygen species (ROS) overproduction and excessive autophagosome accumulation, accompanied with inhibition of phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) pathway. Subsequently, we confirmed that 3,6-DCCZ exposure triggered hepatic uncontrolled inflammatory response via activation of nuclear factor-κB (NF-κB) pathway, along with decreased plasma complement C3 (C3) and complement C4 (C4) levels. Meanwhile, yellow catfish exposed to 3,6-DCCZ exhibit an increased hepatic apoptosis phenomenon, as evidenced by the elevated number of positive TUNEL cells and upregulated expression of caspase3 and cytochrome C (CytC). In contrast, LYC treatment could alleviate the 3,6-DCCZ-induced pathological changes, hepatic ROS accumulation, autophagy, inflammatory response and apoptosis. To sum up, this study provided the demonstration that LYC exerts hepatoprotective effects to alleviate 3,6-DCCZ-induced liver damage by inihibiting ROS/PI3K-AKT/NF-κB signaling in yellow catfish.

Mulberrin alleviates triclocarban induced hepatic apoptosis and inflammation by regulating the ROS/NF-κB pathway in grass carp.

Triclocarban (TCC) is commonly used in household, personal care and industrial products and has been frequently detected in different aquatic ecosystems. Mulberrin (Mul) is a key component of the traditional Chinese medicine Romulus Mori with antioxidant and anti-inflammatory properties. The present study aimed to investigate the hepatotoxic effects of TCC in aquatic organisms and explore the protective roles of Mul. Herein, we found that exposure to TCC at environmentally realistic concentrations (5 µg/L) could impair liver function, along with impaired antioxidant defense and infiltration of inflammatory cells. Additionally, we found that TCC increased the ratio of TUNEL staining positive cells, accompanied by upregulation of pro-apoptotic protein (Bax, caspase3 and caspase9), and downregulation of anti-apoptotic proteins (Bcl2). In contrast, Mul supplementation reversed the hepatic pathological damage, ROS elevation, and apoptosis induced by TCC, likely due to hyperactivation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Additionally, Mul supplementation suppressed the mRNA levels of proinflammatory factors (TNF-α, IL-1ß, IFN-γ, IL-6 and IL-8) and enhanced the mRNA levels of anti-inflammatory factors (TGFß1, TGFß2, IL4, IL10 and IL11) in the liver of carp. We also discovered that Mul supplementation suppressed TCC-induced nuclear nuclear factor κB (NF-κB) elevation. In conclusion, Mul enhances Nrf2 signaling cascades and counteracts the NF-κB inflammatory program to rescue hepatotoxicity induced by TCC, providing new insights into the hepatotoxic effects of TCC and potential protection strategies for heart injury induced by TCC.