Lei Wang1, Dan Yi1, Yongqing Hou2, Binying Ding1, Kang Li1, Baocheng Li1, Huiling Zhu1, Yulan Liu1, Guoyao Wu3. 1. Hubei Key Laboratory of Animal Nutrition and Feed Science, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, China; and. 2. Hubei Key Laboratory of Animal Nutrition and Feed Science, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, China; and houyq@aliyun.com g-wu@tamu.edu. 3. Hubei Key Laboratory of Animal Nutrition and Feed Science, Hubei Collaborative Innovation Center for Animal Nutrition and Feed Safety, Wuhan Polytechnic University, Wuhan, China; and Department of Animal Science, Texas A&M University, College Station, TX houyq@aliyun.com g-wu@tamu.edu.
Abstract
BACKGROUND: Skeletal muscle undergoes rapid loss in response to inflammation. α-Ketoglutarate (AKG) has been reported to enhance muscle growth in piglets, but the underlying mechanisms are largely unknown. OBJECTIVES: This study tested the hypothesis that dietary AKG supplementation activates mechanistic target of rapamycin (mTOR) signaling and improves skeletal muscle energy metabolism in lipopolysaccharide (LPS)-challenged piglets. METHODS: Forty-eight male piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age to a corn- and soybean meal-based diet. After a 3-d period of adaptation, piglets with a mean weight of 7.21 kg were randomly assigned to control, LPS (intraperitoneal administration of 80 μg LPS/kg body weight on days 10, 12, 14, and 16), or LPS plus 1% dietary AKG (LPS+AKG) groups. On day 16, blood samples were collected from 8 piglets/group 3 h after LPS administration. On day 17, piglets were killed to obtain gastrocnemius muscle from 8 piglets/group for biochemical analysis. RESULTS: Compared with the control group, LPS administration increased (P < 0.05) plasma concentrations of globulin (by 14%) and tumor necrosis factor α (by 59%) and the intramuscular ratio of AMP to ATP (by 93%) and abundance of phosphorylated acetyl-coenzyme A carboxylase (ACC) β protein (by 64%). Compared with the control group, LPS administration reduced (P < 0.05) weight gain (by 15%); plasma concentrations of glutamine (by 20%), glucose (by 23%), insulin, insulin-like growth factor I, and epidermal growth factor; intramuscular concentrations of glutamine (by 27%), ATP (by 12%), ADP (by 22%), and total adenine nucleotides; and intramuscular ratios of phosphorylated mTOR to total mTOR (by 38%) and of phosphorylated 70-kDa ribosomal protein S6 kinase (p70S6K) to total p70S6K (by 39%). These adverse effects of LPS were ameliorated (P < 0.05) by AKG supplementation. CONCLUSIONS: Dietary AKG supplementation activated mTOR signaling, inhibited ACC-β, and improved energy status in skeletal muscle of LPS-challenged piglets. These results provide a biochemical basis for the use of AKG to enhance piglet growth under inflammatory or practical postweaning conditions.
BACKGROUND: Skeletal muscle undergoes rapid loss in response to inflammation. α-Ketoglutarate (AKG) has been reported to enhance muscle growth in piglets, but the underlying mechanisms are largely unknown. OBJECTIVES: This study tested the hypothesis that dietary AKG supplementation activates mechanistic target of rapamycin (mTOR) signaling and improves skeletal muscle energy metabolism in lipopolysaccharide (LPS)-challenged piglets. METHODS: Forty-eight male piglets (Duroc × Landrace × Yorkshire) were weaned at 21 d of age to a corn- and soybean meal-based diet. After a 3-d period of adaptation, piglets with a mean weight of 7.21 kg were randomly assigned to control, LPS (intraperitoneal administration of 80 μg LPS/kg body weight on days 10, 12, 14, and 16), or LPS plus 1% dietary AKG (LPS+AKG) groups. On day 16, blood samples were collected from 8 piglets/group 3 h after LPS administration. On day 17, piglets were killed to obtain gastrocnemius muscle from 8 piglets/group for biochemical analysis. RESULTS: Compared with the control group, LPS administration increased (P < 0.05) plasma concentrations of globulin (by 14%) and tumornecrosis factor α (by 59%) and the intramuscular ratio of AMP to ATP (by 93%) and abundance of phosphorylated acetyl-coenzyme A carboxylase (ACC) β protein (by 64%). Compared with the control group, LPS administration reduced (P < 0.05) weight gain (by 15%); plasma concentrations of glutamine (by 20%), glucose (by 23%), insulin, insulin-like growth factor I, and epidermal growth factor; intramuscular concentrations of glutamine (by 27%), ATP (by 12%), ADP (by 22%), and total adenine nucleotides; and intramuscular ratios of phosphorylated mTOR to total mTOR (by 38%) and of phosphorylated 70-kDa ribosomal protein S6 kinase (p70S6K) to total p70S6K (by 39%). These adverse effects of LPS were ameliorated (P < 0.05) by AKG supplementation. CONCLUSIONS: Dietary AKG supplementation activated mTOR signaling, inhibited ACC-β, and improved energy status in skeletal muscle of LPS-challenged piglets. These results provide a biochemical basis for the use of AKG to enhance piglet growth under inflammatory or practical postweaning conditions.
Authors: Ashton Faulkner; Anita Tamiato; William Cathery; Andrea Rampin; Carlo Maria Caravaggi; Eva Jover; Steve Allen; Harry Mellor; David Hauton; Lisa C Heather; Gaia Spinetti; Paolo Madeddu Journal: Diabetologia Date: 2020-07-30 Impact factor: 10.122