title: Alteration of inflammatory cytokines, energy metabolic regulators, and muscle fiber type in the skeletal muscle of postweaning piglets.
abstract: This study was conducted to determine the alterations of inflammatory cytokines, energy metabolic regulators, and muscle fiber type in the LM of the piglets postweaning. Crossbred piglets (Landrace × Large White) weaned at 14 d age were randomly selected from 8 litters and slaughtered at 0 (W0), 1 (W1), 3 (W3), 5 (W5), or 7 (W7) days postweaning. The glycogen content, free glucose concentration, and enzyme activities, including ATPase (Na/K, Ca/Mg), creatine kinase, and lactic dehydrogenase (LDH), were detected in the skeletal muscle tissue. Concentrations of proinflammatory cytokines, including IL-1β, IL-6, and tumor necrosis factor-α (TNF-α), and anti-inflammatory cytokines, including IL-10 and transforming growth factor-β1 (TGF-β1), were measured in serum. The mRNA abundance of the above cytokines, energy metabolic regulators, and muscle fiber type related genes were determined via real-time quantitative PCR analysis. The adenosine monophosphate-activated protein kinase α (AMPKα) signaling was measured by Western blot analysis. Our results showed ATPase activities were lower on W7 d but LDH activity was higher on W3 d after weaning ( < 0.05). Serum TNF-α concentration was markedly increased on W1 d, then returned to the value of preweaning ( < 0.05), and almost all the values of inflammatory cytokines were reduced to a low point on W5 d after weaning. Additionally, the IL-6 mRNA abundance was upregulated during W3 to W7 d, but cytokine TNF-α was upregulated just on W7 d ( < 0.05). The mRNA abundance of AMPKα and uncoupling protein (UCP) 3 were both higher on W1 and W3 d, and UCP2 was higher on W7 d postweaning ( < 0.05). Myosin heavy chain (MyHC) I and MyHC IIx-type fibers were enhanced on W1 d, then returned to the value of preweaning, and the MyHC IIb-type fiber was significantly increased on W5 and W7 d ( < 0.05). Meanwhile, the value of P-AMPKα/T-AMPKα increased on W3 d postweaning ( < 0.05) compared with that on W0 d. These results indicate that weaning stress induced inflammation in skeletal muscle tissue during at least 7 d postweaning. It upregulated the expression of proinflammatory cytokines, which then stimulated the AMPKα and UCP involved in energy metabolism events, accompanied by significant alterations in muscle fiber type.
authors.forename: F
authors.initials: F
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.forename: B
authors.initials: B
authors.lastname: Tan
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Duan
authors.forename: Q
authors.initials: Q
authors.lastname: Guo
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: X
authors.initials: X
authors.lastname: Kong
authors.forename: T
authors.initials: T
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Tang
authors.forename: Y
authors.initials: Y
authors.lastname: Yin
mesh_terms: D000818:Animals; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D007249:Inflammation / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000235:genetics; D024501:Nonmuscle Myosin Type IIB; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013552:Swine / Q000502:physiology*
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D024501:Nonmuscle Myosin Type IIB; C103815:nonmuscle myosin type IIB heavy chain; D018995:Myosin Heavy Chains