Effects of Atrolnc-1 on immobilization induced muscular atrophy in mice hindlimbs

Abstract

Objective: To investigate the effects of Atrolnc-1 on immobilization induced muscular atrophy in mice hindlimbs. Methods: Male C57BL/6 mice were randomly divided into control group and immobilization group (n=10 per group). The control group did not receive any treatment. The right hindlimb of the Iimmobilization group was fixed by self-made plastic tube. After 2 weeks' immobilization, the gastrocnemius muscle was separated. Hematoxylin-eosin (HE) staining was used to observe the morphological changes and the cross-sectional area was calculated. The expressions of Atrogin-1 and atrophy-specific long non-coding RNA Atrolnc-1 were detected by quantitative real-time PCR (QRT-PCR). Western blot (WB) was used to detect the expressions of muscular atrophy fbox-1 protein (MAFbx/Atrogin-1), muscle ring finger1 (MuRF-1) in whole cell and phosphonated of nuclear factor kappaB (p-NF-κB) in cytoplasm and nucleus. Results: The gastrocnemius muscle was atrophy after 2 weeks' immobilization. Compared with the control group, the wet weight of gastrocnemius muscle was decreased (P＞0.05) and the permillage of wet weight/weight of gastrocnemius muscle was decreased significantly (P＜0.05). HE staining showed that the number of muscle fibers in the immobilization group were reduced, the muscle fibers were dissolved and arranged disorderly and the interstitial inflammatory cells were infiltrated; the cross-sectional area of muscle fibers was decreased (P＜0.01).The expression level of atrolnc-1 was increased in immobilization group (P＜0.01). The expression level of p-NF-κB in cytoplasm was decreased (P＜0.01), while the expression level of p-NF-κB was increased in nucleus ( P＜0.01). Besides, the expressions of atrogin-1 (P＜0.01) and MuRF-1 (P＜0.01) were increased. Conclusion: Immobilization induced gastrocnemius atrophy in mice may be related to the activation of NF-κB by Atrolnc-1 and then promote MuRF-1 expression.