Heat-induced oxidative stress and inflammation involve in cadmium pollution history in the spleen of zebrafish

Zebrafish were exposed to 0, 2.5 and 5 mu g/L cadmium (Cd) for 10 weeks, and then each group was exposed to 26 degrees C(control) and 32 degrees C (high temperature) for 7 days. 22 indicators were compared between 26 degrees C and 32 degrees C in the spleen, including body weight, LPO and NO levels, activity levels of Cu/Zn-SOD, CAT and iNOS, MTs protein levels, and mRNA levels of Nrf2, Cu/Zn-SOD, CAT, HSF1, HSF2, HSP70, MTF-1, MTs, IL-6, IL-10, IL-beta, TNF-alpha, iNOS and NF-kappa B. Most indicators were not significantly affected by heat in fish from no Cd pollution. However, almost all of indicators were responsive to heat in fish pre-exposed to Cd. Several indicators were sensitive to heat in fish pre-exposed to 2.5 mu g/L Cd such as iNOS activities, and mRNA levels of iNOS and IL-10. Most other indicators were sensitive to heat in fish pre-exposed to 5 mu g/L. The mRNA levels of HSP70 and MTF-1 were up-regulated by heat in fish pre-exposed to 0, 2.5 and 5 mu g/L Cd. However, the magnitude of increase was the greatest in fish pre exposed to 5 mu g/L Cd. These differences between control and high temperature would serve as biomarkers to distinguish healthy from Cd-polluted group. The findings imply that metal pollution history should be carefully considered when screening heat biomarkers in fish. (C) 2017 Elsevier Ltd. All rights reserved.