The uncoupling protein 2 (UCP2) gene belong to the superfamily of electron transport carriers of the mitochondrial inner membrane which is involved in thermogenesis and determining the functional evolution of UCP2 gene is important to understand the evolution of thermo-regulation in chickens. The aim of this study was to investigate the effects of cold stress on the mRNA level of UCP2 in liver of chickens. In this study, 120 15-d-old male chickens were randomly allocated into 12 groups (10 each group) for exposure to acute (up to 24 h) and chronic (up to 20 days) cold stress (12±1°C). This study detected UCP2 mRNA levels in liver, glucagons (GLU) content in plasma, insulin (INS), blood glucose (BG) and free fatty acid (FFA) content in serum. The results showed that during acute cold stress, UCP2 mRNA levels gradually increased the INS and FFA content showed fluctuant change, GLU content gradually increased, and BG content first increased and then decreased. During chronic cold stress, UCP2 mRNA levels significantly increased compared with the control group, and the content of INS, GLU, BG and FFA were all gradually increased with the time lapsing. The results indicated that both acute and chronic cold stress could enhance the energy metabolism and the UCP2 mRNA levels in liver of chicks.

Key words: Chicken, Cold stress, Energy metabolism, Liver, UCP2