Microbe-derived antioxidants enhance lipid synthesis by regulating AMPKα-SREBP1c pathway in liver of weanling piglets.

BACKGROUND: Weaning usually causes low feed intake and weight loss in piglets, which mobilizes lipid to energize. The microbe-derived antioxidants (MA) exhibit great potential in anti-oxidation, anti-inflammation and metabolic regulation.

OBJECTIVE: To investigate the changes of lipid metabolism postweaning and effects of MA on growth performance and hepatic lipid metabolism in weanling piglets.

METHODS: In the first experiment, piglets weaned at 21 days old were slaughtered on weaning day (d0), 4 (d4) and 14 (d14) days postweaning (6 piglets per day). In the second experiment, piglets were divided into two groups, receiving MA (MA) and saline gavage (CON), respectively. All piglets were weaned at 21 days old and 6 piglets from each group were slaughtered at 25 days old.

RESULTS: In the experiment 1, the serum TG, TC and LDL-C on d4 and d14 declined significantly compared with d0 (P < 0.05). The serum leptin on d0 was higher than that on d4 and d14 (P < 0.05). The serum ghrelin kept increasing from d0 to d14 (P < 0.05). The hepatic HSL and ATGL firstly increased from d0 to d4 then decreased from d4 to d14 (P < 0.05). In the experiment 2, the ADG and ADFI from 21-25 days old increased in MA group compared with CON group (P < 0.05). The serum TC, hepatic TC and glucose of MA group showed a significant increase than that of CON group (P < 0.05). The expression of SCD1, ACAT2 and PPARγ were upregulated in MA group (P < 0.05). Contrary to the decreased expression of p-AMPKα (Thr172), the nuclear SREBP1c, FASN and PPARγ of MA group increased than that of CON group (P < 0.05).

CONCLUSIONS: Weaning promoted hepatic lipolysis and MA could enhance lipid synthesis by regulating AMPKα-SREBP1c pathway, thus improving growth performance of weanling piglets.