Protective effects of tree peony seed protein hydrolysate on Cd-induced oxidative damage, inflammation and apoptosis in zebrafish embryos

The objective of this study was to investigate protective effects of tree peony seed protein hydrolysate by Alcalase (AL-TPSPH) on oxidative damage, inflammation and apoptosis using Cd-induced zebrafish embryos. Zebrafish embryos were treated with either Cd (2 μg/L) or AL-TPSPH (25, 50 and 75 μg/mL) alone or in combination of both from 4 to 144 h post fertilization (hpf). The effects of these treatments on developments, antioxidant parameters and mRNA expression of genes related to oxidative damage, inflammation and apoptosis were examined. The results showed that co-treatment with Cd and AL-TPSPH significantly increased hatching and survival rates and decreased malformation rates of zebrafish embryos compared with Cd treatment alone group (P < 0.05). Cd-induced increase of MDA content, decreases of T-AOC content, GSH/GSSG ratio and activities of SOD, CAT and GPx in zebrafish embryos were modified upon treatment with AL-TPSPH. AL-TPSPH treatment significantly suppressed Cd-induced down-regulations of the antioxidant gene expressions (Mn-sod, Cat and GPx1a) in zebrafish embryos (P < 0.05). AL-TPSPH also prevented Cd-induced up-regulations of pro-inflammatory cytokine (TNF-α, IL-1β and IFN-γ) expressions. Moreover, AL-TPSPH inhibited Cd-induced up-regulations of pro-apoptotic genes (C-jun, Caspase-3 and Caspase-9) in zebrafish embryos. Collectively, these results indicated that AL-TPSPH could reduce Cd-induced oxidative damage, inflammation and apoptosis in zebrafish embryos, suggesting its future applications as functional food or pharmaceutical ingredient.