Saponins of Panax japonicus ameliorates cardiac aging phenotype in aging rats by enhancing basal autophagy through AMPK/mTOR/ULK1 pathway.

Heart disease is a significant health concern for elderly individuals, with heart aging being the primary cause. Recent studies have shown that autophagy can play a protective role in preventing cardiac aging. Our previous research confirmed that Chikusetsu saponin IVa, a fundamental component of Saponins of Panax japonics (SPJ), can enhance basic autophagy levels in cardiomyocyte of isoproterenol induced cardiac fibrosis mice. However, it remains unclear whether SPJ possesses a protective effect on cardiac dysfunction during the natural aging process. Rats were randomly divided into four groups: adult control group (6 months old), aging group (24 months old), aging group treated with 10 mg/kg SPJ, and aging group treated with 30 mg/kg SPJ. The heart function, blood pressure, and heart mass index (HMI) were measured. Hematoxylin and eosin staining (H&E) and Wheat Germ Agglutinin (WGA) staining were used to observe the changes in morphology, while Masson staining was used to examine collagen deposition in the rat hearts and CD45 immunohistochemistry was conducted to examine the macrophage infiltration in heart tissues. TUNEL kit was used to detect apoptosis level of cardiomyocyte, and western blot was used to evaluate autophagy-related proteins as well as AMPK/mTOR/ULK1 pathway-related markers. SPJ treatment improved the cardiac function, reduced HMI, attenuated myocardial fiber disorder, inhibited inflammatory cell infiltration, and decreased collagen deposition and cardiomyocyte apoptosis in aging rats. Additionally, SPJ treatment decreased the expression of aging-related proteins and restored the expression of autophagy-related markers. SPJ activated autophagy through the activation of AMPK, which in turn increased the phosphorylation of ULK1(Ser555), while inhibited the phosphorylation of mTOR and ULK1(Ser757). Our study demonstrates that SPJ improves the cardiac function of aging rats by enhancing basal autophagy through the AMPK/mTOR/ULK1 pathway. These results offer a theoretical foundation and empirical evidence to support the clinical advancement of SPJ in enhancing age-related cardiac dysfunction.

Chikusetsu saponin IVa attenuates isoprenaline-induced myocardial fibrosis in mice through activation autophagy mediated by AMPK/mTOR/ULK1 signaling.

BACKGROUND: Myocardial fibrosis is a common pathological manifestation of many cardiovascular diseases at the end stage. Autophagy has been demonstrated to play a protective role in the cardiac fibrosis. Our previous studies have demonstrated that the Saponins from Panax japonicus effectively ameliorated the degree of fibrosis in rat acute myocardial ischemia injury model though the mechanisms are not clear. HYPOTHESIS: We hypothesized that Chikusetsusaponin IVa (CS), a major component of Saponins from Panaxjaponicus, may improve isoprenaline induced myocardial fibrosis via AMPK/mTOR/ULK1 mediated autophagy METHODS: Continuous subcutaneous injection of isoproterenol for 21 days was used to induce myocardial fibrosis in mice and high and low doses (15 mg/kg and 5 mg/kg) of CS was administered by oral gavage to observe the efficacy. Animals were sacrificed 12 h after the last administration and samples were collected. H&E staining, Masson staining and wheat germ agglutinin (WGA) staining were used to evaluate histopathological changes, collagen deposition and myocardial cell hypertrophy. Autophagy-related markers (LC3ß, Beclin1 and p62) and AMPK/mTOR/ULK1 pathway-related markers were evaluated by western blot. RESULTS: CS effectively attenuated isoprenaline-induced myocardial fibrosis in vivo, reduced the heart index, inhibited inflammatory infiltration, decreased collagen deposition and myocardial cell size. CS treatment rescued the expression of autophagy-related markers. CS activated autophagy through the activation of AMPK, which in turn inhibited the phosphorylation of mTOR and ULK1(Ser757), rather than directly phosphorylate ULK1(Ser555) by AMPK. CONCLUSION: Our data demonstrated that CS attenuated isoprenaline-induced myocardial fibrosis by activating autophagy through AMPK/mTOR/ULK1 pathway. Our findings suggested that CS is a potential candidate drug against cardiac fibrosis and have identified potential drug targets for the treatment of heart diseases.

[Effect of saponins extracted from Panax japonicas on inhibiting myocardial fibrosis by TGF-ß1/Smad3 signaling pathway in aging rats].

To investigate the amelioration effect of saponins extracted from Panax japonicas (SPJ) on myocardial fibrosis in natural aging rats and its mechanisms, male SD rats aged 18 months were randomly divided into 3 groups (aging model group, low-dose SPJ group and high-dose SPJ group), with 10 rats in each group. SPJ groups were given SPJ at different doses (10, 60 mg·kg⁻¹·d⁻¹) consecutively for 6 months, meanwhile, aging model group was treated with the equal volume of saline for 6 months until 24 months old. Another 10 rats aged 6 month were used as young control group. The changes of myocardial morphological were observed by haematoxylin-eosin (HE) staining. Masson staining was used to observe the changes of collagen deposition in rat hearts. RT-PCR was used to detect the mRNA expression levels of myofibroblast marker α-SMA, collagen-related protein COL1α2, COL3α1 and matrix metalloproteinase MMP2, MMP9. Western blot was used to test the changes of the protein expressions of TGF-ß1, p-Smad3, IL-1ß and TNF-α in heart tissues. SPJ can effectively improve the arrangement of myocardial fibers, decrease inflammatory infiltration and reduce collagen deposition in aging rats. SPJ can effectively down-regulate the mRNA expression levels of COL1α2, COL3α1, α-SMA, MMP9, MMP2 and inhibit the protein expressions of TGF-ß1, p-Smad3, TNF-α, IL-1ß in the natural aging heart tissues. SPJ can effectively alleviate myocardial fibrosis in natural aging rats, and its mechanisms was related to the inhibition of the protein expressions of TGF-ß1, p-Smad3 and the reduction of myocardial inflammation in rat hearts.

[Effect of saponins extracted from Panax japonicus on inhibiting cardiomyocyte apoptosis by AMPK/Sirt1/NF-κB signaling pathway in aging rats].

To investigate the effects of saponins extracted from Panax japonicus(SPJ) on cardiomyocyte apoptosis in natural aging rats and explore its underlying mechanisms. SD male rats were randomly divided into four groups: young control group, natural aging group, SPJ low dose group and SPJ high dose group, with 10 rats in each group. The rats in natural aging group, SPJ low and high dose groups were respectively treated with normal saline, SPJ 10 and 60 mg•kg-1•d-1 from the beginning of 18 month-old, 6 days per week for 6 months till 24 month-old. Then the animals were sacrificed. Their myocardial morphology changes were observed by using haematoxylin-eoin(HE) staining; cardiomyocyte apoptosis was tested by using Tunel assays; and the protein expression levels of Bcl-2, Bax, IL-1ß, TNF-α, AMPK, p-AMPK, Sirt1, and Ac-NF-κB p65 in myocardial tissues of rats were detected by Western blot. The results showed that SPJ could effectively improve the arrangement disorder of myocardial fibers, reduce the infiltration of inflammatory cells and inhibit cardiomyocyte apoptosis in natural aging rats. At the same time, SPJ could significantly inhibit the protein expression of Bax, IL-1ß, TNF-α and Ac-NF-κB p65, and increase the expression of Bcl-2, Bcl-2/Bax, p-AMPK/AMPK and Sirt1 in the heart tissues of natural aging rats. SPJ can effectively inhibit cardiomyocyte apoptosis in natural aging rats, and its mechanisms may be related with the regulation of inflammatory reaction by AMPK/Sirt1/NF-κB signaling pathway.