Korean red ginseng suppresses mitochondrial apoptotic pathway in denervation-induced skeletal muscle atrophy

Abstract

Background: Skeletal muscle denervation leads to motor neuron degeneration, which in turn reduces muscle fiber volumes. Recent studies have revealed that apoptosis plays a role in regulating denervation-associated pathologic muscle wasting. Korean red ginseng (KRG) has various biological activities and is currently widely consumed as a medicinal product worldwide. Among them, ginseng has protective effects against muscle atrophy in in vivo and in vitro. However, the effects of KRG on denervation-induced muscle damage have not been fully elucidated.

Methods: We induced skeletal muscle atrophy in mice by dissecting the sciatic nerves, administered KRG, and then analyzed the muscles. KRG was administered to the mice once daily for 3 weeks at 100 and 400 mg/kg/day doses after operation.

Results: KRG treatment significantly increased skeletal muscle weight and tibialis anterior (TA) muscle fiber volume in injured areas and reduced histological alterations in TA muscle. In addition, KRG treatment reduced denervation-induced apoptotic changes in TA muscle. KRG attenuated p53/Bax/cytochrome c/Caspase 3 signaling induced by nerve injury in a dose-dependent manner. Also, KRG decreases protein kinase B/mammalian target of rapamycin pathway, reducing restorative myogenesis.

Conclusion: Thus, KRG has potential protective role against denervation-induced muscle atrophy. The effect of KRG treatment was accompanied by reduced levels of mitochondria-associated apoptosis.

Keywords: Korean red ginseng; denervation; mitochondria-activated apoptosis; myogenesis.

Graphical abstract

Fig. 1

Representative photographs of TA, GA, and quadriceps in denervation-induced mice. Nerve dissected muscles are on the right, and contralateral muscles are on the left. DEN; denervation-induced mice, DEN + KRG L; denervation-induced mice + oral administration of low-dose (100 mg/kg/day) of KRG, DEN + KRG H; denervation-induced mice + oral administration of high-dose (400 mg/kg/day) KRG.

Fig. 2

KRG improves the histological alterations and the atrophied muscle fibers size in TA muscles from mice which was confirmed by (A) Harris' hematoxylin and eosin staining (Bar = 30 μm) and (B) immunofluorescence laminin staining (Bar = 25 μm). The nuclei were enlarged and abnormally located (arrowheads). DEN; denervation-induced mice, DEN + KRG L; denervation-induced mice + oral administration of low-dose (100 mg/kg/day) of KRG, DEN + KRG H; denervation-induced mice + oral administration of high-dose (400 mg/kg/day) KRG. Values: means ± SD (n = 7). Significance: ^##p < 0.01 vs SHAM; ∗p < 0.05 vs DEN, respectively.

Fig. 3

KRG reduces the elevated apoptosis in TA muscles (A) and suppresses the elevated pro-apoptotic signals (B). (C) The densitometric values were determined using ChemiDoc. DEN; denervation-induced mice, DEN + KRG L; denervation-induced mice + oral administration of low-dose (100 mg/kg/day) of KRG, DEN + KRG H; denervation-induced mice + oral administration of high-dose (400 mg/kg/day) KRG. Values: means ± SD (n = 7). Significance: ^##p < 0.01 vs SHAM; ∗^,∗∗p < 0.05 and 0.01 vs DEN, respectively.

Fig. 4

KRG reduced the elevated phosphorylation of (A) AKT and mTOR. (B) The densitometric values were determined using ChemiDoc. DEN; denervation-induced mice, DEN + KRG L; denervation-induced mice + oral administration of low-dose (100 mg/kg/day) of KRG, DEN + KRG H; denervation-induced mice + oral administration of high-dose (400 mg/kg/day) KRG. Values: means ± SD (n = 7). Significance: ^##p < 0.01 vs SHAM; ∗∗p < 0.01 vs DEN.

Fig. 5

KRG reduces the elevated (A) myogenin positivity and (B) myogenin expression in TA muscles from mice which was confirmed by IHC and Western blot. DEN; denervation-induced mice, DEN + KRG L; denervation-induced mice + oral administration of low-dose (100 mg/kg/day) of KRG, DEN + KRG H; denervation-induced mice + oral administration of high-dose (400 mg/kg/day) KRG. Values: means ± SD (n = 7). Significance: ^##p < 0.01 vs SHAM; ∗∗p < 0.01 vs DEN.