Gene expressions and metabolomic research on the effects of polyphenols from the involucres of Castanea mollissima Blume on heat-stressed broilers chicks

Abstract

To study the effects of polyphenolic extract from involucres of Castanea mollissima Blume ( PICB: ), a novel approach using gene expression by real time polymerase chain reaction ( REAL-TIME PCR: ) coupled with metabolomic profiling technique was established to explain the mechanism of PICB on heat-stressed broiler chicks. Four thousand 28-day-old male Arbor Acres (AA) broilers were randomly assigned to 5 groups (4 replicates / group, 20 chicks / replicate), in which group 1 was normal control group fed with basic ration; groups 2, 3, 4, and 5 were fed with the basic ration with a supplementation of 0.2% Vitamin C ( VC: ), or 0.2%, 0.3%, or 0.4% of PICB respectively. After 1 wk of adaptation, heat stress was applied for 7 consecutive days. On d 3 and d 7 of heat stress, the chicks were sacrificed and sampled. The mRNA expression of heat stress protein 70 (HSP70), glutathione peroxidase ( GSH-PX: ), ornithine decarboxylase ( ODC: ), epidermal growth factor ( EGF: ) and epidermal growth factor receptor ( EGFR: ) were detected by real-time PCR using samples from jejunum mucosa. The serum and jejunum mucosa metabolomic profiles of PICB group showing best antioxidative effects and control group at d 3 were studied using the method of the gas chromatography - time of flight mass spectrometry ( GT-TOF-MS: ), followed by principal component analysis and partial least squares-discriminate analysis. Potential biomarkers were found using Student's t-test. The results showed mRNA expressions of HSP70, GSH-Px, ODC, EGF, and EGFR were altered by the supplementation of PICB. PICB exhibited antioxidative and growth promoting effects, and 0.3% PICB supplementation level exhibited the best. Three metabolites in the serum and 5 in the jejunum mucosa were identified as potential biomarkers. They were considered to be in accordance with antioxidative and growth promoting effects of PICB, which involved in the energy metabolism (sorbitol, palmitic acid), carbohydrate metabolism, amino acids metabolism (serine, L-ornithine), glutathione metabolism (glutamate, L-ornithine), GnRH signaling pathway (inositol), etc. These findings provided novel insights into our understanding of molecular mechanism of PICB effects on heat-stressed chicks.