Dietary Epigallocatechin-3-Gallate (EGCG) Improves Nonspecific Immune Response of Chinese Rice Field Eel (Monopterus albus)

Haichao Deng; Huamei Yue; Rui Ruan; Huan Ye; Zhong Li; Chuangju Li

doi:10.1155/2023/6512136

Dietary Epigallocatechin-3-Gallate (EGCG) Improves Nonspecific Immune Response of Chinese Rice Field Eel (Monopterus albus)

Aquac Nutr. 2023 Nov 15:2023:6512136. doi: 10.1155/2023/6512136. eCollection 2023.

Authors

Haichao Deng^{1

2}, Huamei Yue², Rui Ruan², Huan Ye², Zhong Li³, Chuangju Li²

Affiliations

¹ College of Fisheries and Life Sciences, Shanghai Ocean University, Shanghai 201306, China.
² Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture and Rural Affairs of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
³ Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.

Abstract

Epigallocatechin-3-gallate (EGCG) has been recognized as a potential additive for aquafeeds due to its beneficial biological functions. In order to evaluate the potential application of EGCG in Chinese rice field eel (Monopterus albus), six isonitrogenous and isolipidic diets containing 0, 25, 50, 100, 200, and 400 mg/kg EGCG were formulated and were fed to Monopterus albus (M. albus) for 9 weeks. The results showed that M. albus fed diets containing 0 and 100 mg/kg EGCG presented higher weight again and specific growth rate than the other groups. Fish fed with 25, 50, and 400 mg/kg EGCG displayed lower whole-body lipid content. Serum aspartate aminotransferase (AST) concentration significantly decreased in EGCG treated groups with the exception of 100 mg/kg group. Hepatic catalase (CAT) activity and glutathione (GSH) concentration decreased as EGCG level increased while malondialdehyde (MDA) concentration showed an opposite trend. EGCG supplementation resulted in a promoted lysozyme (LZM) activity and immunoglobulin M (IgM) level in the liver of M. albus. Furthermore, transcription of three immune related genes including major histocompatibility complex (mhc-2α), hepcidin, and interleukin-8 (il-8) mRNAs was upregulated by EGCG treatment; while transcription of interleukin-6 (il-6) and nuclear factor kappa-B (nf-kb) genes was downregulated. Results also showed a linear relation between EGCG inclusion level and parameters of AST, CAT, GSH, MDA, LZM, IgM, and immune-related genes transcriptions. In summary, it could be suggested that EGCG supplementation enhanced the nonspecific immune response of the Chinese rice field eel. Based on the broken-line regression analysis of IgM, the optimal dietary EGCG supplementation for M. albus was estimated to be 109.81 mg/kg.