Shikonin Inhibits Fin Regeneration in Zebrafish Larvae.

Shikonin is a naphthoquinone compound extracted from Chinese comfrey for treating cancer. However, there are few reports on its research on vertebrate tissue regeneration. Zebrafish is an ideal model for studying organ regeneration. In this study, we found that 3-dpf of zebrafish larvae exposed to shikonin at concentrations of 0.2, 0.3, and 0.4 mg/L showed increasingly inhibited regeneration of the tail fin. Immunohistochemical staining showed that shikonin exposure from 6 to 12 hpa increased the number of apoptotic cells in the caudal fin wound of larvae and decreased the number of proliferating cells. Shikonin exposure was found to up-regulate oxidative stress, increase ROS levels, and reduce neutrophil recruitment in the early stage of wound repair. Moreover, shikonin exposure caused disordered expression of fin regeneration blastemal-related genes. The use of astaxanthin to down-regulate oxidative stress was found to significantly reduce the inhibition of caudal fin regeneration. Mixed exposure of AMPK inhibitors or fullerenes (C60) with shikonin also showed the similar rescue effect. Collectively, our study showed that shikonin inhibited fin regeneration in zebrafish larvae by the upregulation of oxidative stress level and AMPK signaling pathway. This research provides valuable information on the mechanism of action of shikonin for its safe application.

Cyclosporine A Induces Cardiac Developmental Toxicity in Zebrafish by Up-Regulation of Wnt Signaling and Oxidative Stress.

Due to the widely application of Cyclosporine A (CsA) as an immunosuppressant in clinic, it is necessary to study its potential toxicity. Therefore, we used zebrafish as a model animal to evaluate the toxicity of CsA on embryonic development. Exposure of zebrafish embryos to CsA at concentrations of 5 mg/L, 10 mg/L, and 15 mg/L from 12 hpf to 72 hpf resulted in abnormal embryonic development, including cardiac malformation, pericardial edema, decreased heart rate, decreased blood flow velocity, deposition at yolk sac, shortened body length, and increased distance between venous sinus and arterial bulb (SV-BA). The expression of genes related to cardiac development was disordered, and the apoptotic genes were up-regulated. Oxidative stress level was up-regulated and accumulated in pericardium in a dose-dependent manner. Astaxanthin (ATX) treatment could significantly alleviate zebrafish heart defects. CsA induced up-regulation of Wnt signaling in zebrafish, and IWR-1, an inhibitor of Wnt signaling pathway, could effectively rescue the heart defects induced by CsA. Together, our study indicated that CsA induced cardiac developmental toxicity in zebrafish larvae through up-regulating oxidative stress and Wnt signaling, contributing to a more comprehensive evaluation of the safety of the drug.

Effect of fomesafen on the embryonic development of zebrafish.

Fomesafen is widely used in agriculture and can be detected in the environment and agricultural products. Research on the developmental toxicity of fomesafen in animals is currently very limited. Here, we used zebrafish as an animal model to evaluate the toxicity of fomesafen in developing aquatic vertebrates and higher animals. From 6h to 72h following fertilization, exposure of zebrafish embryos to 5, 10 and 20 mg/L of fomesafen resulted in pericardial edema, a reduction in heart rate, shortening of body length, and yolk sac edema. Fomesafen reduced the number of immune cells such as neutrophils and macrophages, increased the expression of a number of inflammatory factors, induced the up-regulation of the oxidative stress response and apoptosis, and disrupted the activity of enzymes related to nerve development, which affected the motility of the embryos. In conclusion, the results provide new evidence for the comprehensive assessment of fomesafen toxicity in aquatic vertebrates.