Responses of the Nrf2/Keap1 signaling pathway in Mugilogobius abei (M. abei) exposed to environmentally relevant concentration aspirin

Ecotoxicity effect of aspirin on the larvae of Musca domestica through retinol metabolism

Aspirin is a widely used multi-efficiency pharmaceutical, and its environmental residues are frequently detected. However, limited information is available on its effects on the development of the public health pest and saprophytic insect Musca domestica. In this study, it was demonstrated that aspirin inhibits the larval growth of house flies in a concentration-dependent manner. Microbiome analysis indicated that the composition of larval intestinal bacteria was influenced by aspirin but not greatly. The dominant bacterial genus in the aspirin group was still Klebsiella, as in the control group. Transcriptome sequencing and gene set enrichment analysis showed that retinol metabolism was activated after aspirin treatment. High performance liquid chromatography indicated that the content of retinol in larvae was decreased and that of retinoic acid was increased. The addition of β-carotene, a precursor substance of retinol, in feeding promotes larval development and alleviates the inhibitory effect caused by aspirin. In contrast, retinoic acid delayed the larval development of house flies as well as aspirin. Gene expression analysis after aspirin exposure demonstrated that genes involved in the transformation from retinol to retinoic acid were upregulated. Overall, aspirin exposure impairs larval development by activating retinol metabolism in house flies and can be utilized as an effective pesticide. This work uncovers the mechanism underlying the larval development inhibition induced by aspirin in terms of metabolism and genetics, and provides novel functional exploration of a traditional drug for pest management.

Effects of atorvastatin on the Sirtuin/PXR signaling pathway in Mugilogobius chulae

Atorvastatin (ATV) is a hypolipidemic drug widely detected in the aquatic environment. Nevertheless, limited information is provided about the toxic effects of ATV on estuary or coastal species and the underlying mechanisms. In the present study, the responses of genes expression in pregnane X receptor (PXR) signaling pathway and enzymatic activities in the liver of the estuarine benthic fish (Mugilogobius chulae) were investigated under acute and sub-chronic ATV exposure. Results showed that PXR was significantly inhibited in the highest exposure concentration of ATV for a shorter time (24 h, 500 μg L^-1) but induced in a lower concentration (72 h, 5 μg L^-1). The downstream genes in PXR signaling pathway such as CYP3A, SULT, UGT, and GST showed similar trends to PXR. P-gp and MRP1 were repressed in most treatments. GCLC associated with GSH synthesis was mostly induced under ATV exposure for a long time (168 h), suggesting that reactive oxygen species (ROS) were generated under ATV exposure. Similarly, GST and SOD enzymatic activities significantly increased in most exposure treatments. Under ATV exposure, SIRT1 and SIRT2 displayed induction to some extent in most treatments, suggesting that SIRTs may affect PXR expression by regulating the acetylation levels of PXR. The investigation demonstrated that ATV exposure affected the expression of the Sirtuin/PXR signaling pathway, thus further interfered adaption of M. chulae to the environment.

Atorvastatin causes oxidative stress and alteration of lipid metabolism in estuarine goby Mugilogobius abei

The potential effects of the environmental residues of Atorvastatin (ATV) as a widely used antilipemic agent on aquatic organisms deserve more investigations because of its high detection frequency in environment. The responses of Nrf2/Keap1 signaling pathway (including the transcriptional expression of Nrf2, Keap1, GCLC, GPx, GST, SOD, CAT, Trx2, TrxR, HMG-CoAR and PGC-1α) in Mugilogobius abei were investigated under acute and sub-chronic exposure of ATV in the simulated laboratory conditions. The changes of related enzymatic activity (GST, GPx, SOD, CAT and TrxR) and the content of GSH and MDA combining with the observation of histology sections of liver in M. abei were also addressed. The results show Nrf2 and its downstream antioxidant genes were induced to different degrees under ATV exposure. The activities of antioxidant enzymes were inhibited at 24 h and 72 h but induced/recovered at 168 h. Correspondingly, negatively correlated to GSH, MDA increased first but reduced then. Notably, with the increase of exposure concentration/time, the volume of lipid cells in liver decreased, suggesting more lipid decomposition. Therefore, lipid metabolism was suppressed (down-regulation of PGC-1α) and cholesterol biosynthesis was induced (up-regulation of HMG-COAR) at 168 h. In short, ATV brings oxidative stress to M. abei in the initial phase. However, with the increase of exposure time, ATV activates Nrf2/Keap1 signaling pathway and improves the antioxidant capacity of M. abei to reverse this adverse effect. ATV also affects lipid metabolism of M. abei by reducing cholesterol content and accelerating lipid decomposition.

Bioactive Peptide F2d Isolated from Rice Residue Exerts Antioxidant Effects via Nrf2 Signaling Pathway

Studies have shown that the peroxidation caused by oxygen free radicals is an important reason of vascular endothelial dysfunction and multiple diseases. In this study, active peptides (F2ds) were isolated from the fermentation product of rice dregs and its antioxidant effects were approved. Human umbilical vein endothelial cells (HUVECs) stimulated by H2O2 were used to evaluate the antioxidation effect and its molecular mechanism in the oxidative stress model. F2d protected H2O2-induced damage in HUVECs in a dosage-dependent manner. F2d can reduce the expression of Keap1, promote the expression of Nrf2, and activate the downstream target HO-1, NQO1, etc. It means F2d can modulate the Nrf2 signaling pathway. Using Nrf2 inhibitor ML385 to block the Nrf2 activation, the protective function of F2d is partially lost in the damage model. Our results indicated that F2d isolated from rice exerts antioxidant effects via the Nrf2 signaling pathway in H2O2-induced damage, and the work will benefit to develop functional foods.