Effects Of α-Ketoglutarate On Energy Metabolism Of Muscles, Intestinal Mucosa And Livers In Weanling Piglets Chronically Challenged With Lipopolysaccharide

The aim of the current study was to evaluate effects of dietary supplementation withα-ketoglutarate (AKG) on muscle, intestinal mucosa, and liver energy metabolism with reference to its molecular mechanism in weaned pigs after repetitive stimulation with lipopolysaccharide (LPS). Piglets were assigned to a 2×2 factorial arrangements with LPS challenge (with, without) and dietary supplementation of AKG (1%, 0%) as the main factors, total four treatments. Twenty four weaned piglets (Large White×Landrace×Duroc, 6.79±0.32 kg BW) were randomly allocated to one of four treatment groups (each group 6 replicates, one pig per replicate). Four treatment groups are:①LPS challenge (+LPS), 0% AKG supplementation (-AKG);②LPS challenge, 1% AKG supplementation (+AKG);③without LPS challenge (-LPS), 0% AKG;④without LPS challenge, 1% AKG supplementation. LPS challenged piglets were given a single intraperitoneal injection of 100μg/kg BW LPS at 10, 13, 15 d and the remaining piglets were injected intraperitoneally with physiological saline at the same volume. On 16 d, all pigs were killed under anesthesia and gastrocnemius, intestinal mucosa, and liver tissues were excised. Gastrocnemius, intestinal mucosa, and liver adenine nucleotide were assayed by HPLC, western blot assays were performed for gastrocnemius, intestinal mucosa, and liver AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) expression and their phosphorylation.Results showed that:1. Effects ofα-Ketoglutarate on muscle energy metabolism in weanling pigs chronically challenged with lipopolysaccharide(1) Dietary supplementation of 1% AKG increased ADP (P<0.05), attenuated the increase of AMP level and AMP/ATP and the decrease of ADP and energy charge (EC) induced by LPS challenge (P<0.05). (2) AKG supplementation and LPS challenge had no effects on the expression and phosphorylation of AMPK. (3) Dietary supplementation of 1% AKG significantly inhibited ACC phosphorylation; LPS challenge significantly increased the expression and phosphorylation of ACC (P<0.05).2. Effects ofα-Ketoglutarate on intestinal mucosa energy metabolism in weanling pigs chronically challenged with lipopolysaccharide(1) Dietary supplementation of 1% AKG significantly increased EC in in duodenum mucosa and ATP level in ileum mucosa (P<0.05), tended to increased ATP level in duodenum mucosa (P=0.09) , and significantly decreased AMP and AMP/ATP in jejunum and ileum mucosa (P<0.05); attenuated the decrease of ATP level and EC induced by LPS challenge in ileum mucosa (P<0.05). LPS challenge tend to decreased EC in duodenum mucosa (P=0.07), significantly decreased ADP level in ileum mucosa (P<0.05), significantly increased AMP and AMP/ATP in jejunum and ileum mucosa (P<0.05). (2) Dietary supplementation of 1% AKG tend to attenuated the increase of pAMPK/AMPK induced by LPS challenge in jejunum mucosa (P=0.05). LPS challenge significantly increased pAMPK/AMPK in jejunum and ileum mucosa (P<0.05). (3) AKG supplementation attenuated the decrease of ACC expression induced by LPS challenge in ileum mucosa (P<0.05). AKG significantly increased ACC expression in ileum mucosa (P<0.05), decreased pACC/ACC in jejunum and ileum mucosa (P<0.05). LPS challenge significantly increased pACC/ACC in jejunum and ileum mucosa (P<0.05).3. Effects ofα-Ketoglutarate on liver energy metabolism in weanling pigs chronically challenged with lipopolysaccharide.(1) AKG supplementation attenuated the decrease of ATP, ADP level and TAN in liver (P<0.05). AKG supplementation significantly increased TAN (P<0.05), while LPS challenge significantly decreased TAN (P<0.05). (2) AKG supplementation and LPS challenge had no effects on the expression and phosphorylation of AMPK. (3) AKG supplementation significantly decreased pACC/ACC (P<0.05).In short, under the present experimental conditions:1. LPS challenge resulted in muscle energy depletion; dietary supplementation of 1% AKG could maintain muscle energy metabolism; AKG may improve muscle energy status via ACC signaling, therefore alleviate energy metabolism status induced by LPS challenge.2. LPS regulated intestinal mucosa AMPK activity on an AMP-dependent mechanism, and influented intestinal mucosa energy metabolism via AMPK/ACC passway; AKG relieves LPS-induced intestinal mucosa energy depletion, then play a protective effect on intestinal mucosa.3. LPS challenge resulted in liver energy depletion; dietary supplementation of 1% AKG could maintain liver energy metabolism; AKG may improve liver energy status via ACC signaling, therefore alleviate growth inhibition induced by LPS challenge.