Abstract: 【Aim】 To study the effect of earthworm extract on the oxidative stress and antioxidant enzyme contents in the midgut of the silkworm, Bombyx mori, so as to explore the antioxidant function of earthworm extract. 【Methods】 The 5th instar larvae of B. mori were fed with mulberry leaves treated with the 50-, 100- and 200-fold dilutions of the original earthworm (Eisenia foetida) extract solution, respectively, the contents of malondialdehyde (MDA) and lactate dehydrogenase (LDH) as the products of oxidative damage in the midgut of the larvae treated for 6 d were determined, the expression levels of key antioxidant enzyme genes Cat, Sod and GSH-Px were assessed by quantitative real-time PCR, and the contents of antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the total antioxidant capacity (T-AOC) were detected by enzyme linkedimmunosorbent assay. 【Results】 The contents of MDA, CAT, SOD and GSH-Px and the T-AOC in the 50-, 100- and 200-fold dilution treatment groups showed no significant difference from those in the control group, and the LDH content in the 200-fold dilution treatment group was significantly decreased by 9.85% as compared to that in the control group. The expression levels of Cat and GSH-Px in the 100-fold dilution treatment group was significantly higher than those in the control group. The expression levels of Sod in the three dilution treatment groups were significantly higher than that in the control group. 【Conclusion】 Dietary earthworm extract can improve the antioxidant capacity in B. mori by reducing the LDH content and increasing the expression level of antioxidant enzyme genes.

Key words: Bombyx mori; Eisenia foetida, earthworm extract, oxidative stress, antioxidant enzymes, lactate dehydrogenase, total antioxidant capacity