trans 10, cis 12, but Not cis 9, trans 11 Conjugated Linoleic Acid Isomer Enhances Exercise Endurance by Increasing Oxidative Skeletal Muscle Fiber Type via Toll-like Receptor 4 Signaling in Mice

Abstract

Conjugated linoleic acid (CLA) has been implicated in regulating muscle fiber. However, which isomer elicits this effect and the underlying mechanisms remain unclear. Here, male C57BL6/J mice and C2C12 cells were treated with two CLA isomers, and the exercise endurance, skeletal muscle fiber type, and involvement of Toll-like receptor 4 (TLR4) signaling were assessed. The results demonstrated that dietary t10, c12, but not c9, t11-CLA isomer enhanced exercise endurance of mice (from 115.88 ± 11.21 to 130.00 ± 15.84 min, P < 0.05) and promoted the formation of oxidative muscle fiber type of gastrocnemius muscle (from 0.15 ± 0.04 to 0.24 ± 0.05, P < 0.05). Consistently, t10, c12-CLA isomer increased the mRNA expression of oxidative muscle fiber type in C2C12 myotubes (from 1.00 ± 0.08 to 2.65 ± 1.77, P < 0.05). In addition, t10, c12-CLA isomer increased TLR4 signaling expression in skeletal muscle and C2C12 myotubes. More importantly, knockdown of TLR4 eliminated the t10, c12-CLA isomer-induced enhancement of exercise endurance in mice and elevation of oxidative muscle fiber type in C2C12 myotubes and gastrocnemius muscle. Together, these findings showed that t10, c12, but not c9, t11-CLA isomer enhances exercise endurance by increasing oxidative skeletal muscle fiber type via TLR4 signaling.

CLA improves the lipo-nutritional quality of pork and regulates the gut microbiota in Heigai pigs

“…23 Previous studies also found that CLA could change the muscle fiber type transformation and promote the formation of an oxidative muscle fiber type in mice and in C2C12 myotubes. 24,25 In addition, we also found that CLA could decrease the content of capric acid (C10:0) in the LDM. Capric acid has been reported to increase the capacity for fatty acid oxidation in skeletal muscle.…”

Conjugated linoleic acid (CLA) reduces intestinal fatty acid uptake and chylomicron formation in HFD-fed mice associated with the inhibition of DHHC7-mediated CD36 palmitoylation and the downstream ERK pathway

“…48 Additionally, our published results demonstrated that t10, c12-CLA, but not c9, t11-CLA enhanced exercise endurance by increasing the oxidative skeletal muscle fiber type in mice. 49 Similarly, 50 μM c9, t11-CLA increased the expression of UCP1 in human precursor adipocytes, while t10, c12-CLA inhibited the expression of UCP1 in human precursor adipocytes after 12 h treatment. 50 The specific reasons why different CLA isomers have different regulatory effects are not clear, but the possible reasons may be the differences in the CLA treatment concentration, experimental duration and cell model.…”

“…48 Additionally, our published results demonstrated that t10, c12-CLA, but not c9, t11-CLA enhanced exercise endurance by increasing the oxidative skeletal muscle fiber type in mice. 49 Similarly, 50 μM c9, t11-CLA increased the expression of UCP1…”

Application of conjugated materials in muscle movement recovery process

“…Duan, Chen said that Conjugated linoleic acid is related to the regulation of muscle fibers. He pointed out through experiments that Conjugated linoleic acid isomers increase the type of oxidized skeletal muscle fibers through toll like receptor 4 signals to enhance exercise endurance ( Duan et al, 2021 ). Scholars’ research on conjugated materials and muscles can provide some theoretical support for this article, but due to the lack of emphasis on the application of conjugated materials in muscle motion recovery, the research does not have much reference value.…”