The Long-Term Consumption of Ginseng Extract Reduces the Susceptibility of Intermediate-Aged Hearts to Acute Ischemia Reperfusion Injury.

A large number of experimental studies using young adult subjects have shown that ginseng (Panax ginseng C.A. Meyer) protects against ischemia heart disease. However, ginseng has not been explored for its anti-I/R effect and mechanism of action in the aged myocardium. The present study was designed to evaluate the effects of the long-term consumption of ginseng extract on myocardial I/R in an in vivo rat model and explore the potential underlying mechanism.Young (6-mo-old) and intermediate-aged (18-mo-old) rats were gavaged with either standardized ginseng extract (RSE) at 80 mg/kg or vehicle for 90 days. The rats were sacrificed after LAD coronary artery ligation was performed to induce 30 min of ischemia, followed by 90 min of reperfusion. The myocardial infarct size was measured. Left ventricular function was evaluated using pressure-volume loops. The levels of survival, apoptotic and longevity protein expression were assessed through Western blot analysis. Myocardial pathology was detected through H&E or Masson's trichrome staining. We observed higher infarct expansion with impairment in the LV functional parameters, such as LVSP and LVEDP, in aged rats compared with young rats. Enhanced Akt phosphorylation and eNOS expression in RSE-treated aged hearts were accompanied with reduced infarct size, improved cardiac performance, and inducted survival signals. In contrast, p-Erk and caspase 7 were significantly downregulated in aged rats, suggesting that cardiomyocyte apoptosis was suppressed after RSE treatment. RSE also inhibited caspase-3/7 activation and decreased Bax/Bcl-2 ratio. Consistent with the results of apoptosis, Sirt1 and Sirt3 were significantly increased in the RSE-treated aged heart compared with vehicle-treated I/R, suggesting that the anti-aging effect was correlated with the anti-apoptotic activity of RSE.These findings suggest that the long-term consumption of ginseng extract reduced the susceptibility of intermediate-aged hearts to acute ischemia reperfusion injury in rats. These effects might be mediated through the activation of Akt/eNOS, suppression of Erk/caspase 7 and upregulation of Sirt1 and Sirt3 in intermediate-aged rats

Effectiveness of Panax ginseng

Mechanisms for Panax ginseng’s cardioprotective effect against ischemia reperfusion injury involve the estrogen-mediated pathway, but little is known about the role of androgen. A standardized Panax ginseng extract (RSE) was orally given with or without flutamide in a left anterior descending coronary artery ligation rat model. Infarct size, CK and LDH activities were measured. Time-related changes of NO, PI3K/Akt/eNOS signaling, and testosterone concentration were also investigated. RSE (80 mg/kg) significantly inhibited myocardial infarction and CK and LDH activities, while coadministration of flutamide abolished this effect of RSE. NO was increased by RSE and reached a peak after 15 min of ischemia; however, flutamide cotreatment suppressed this elevation. Western blot analysis showed that RSE significantly reversed the decreases of expression and activation of PI3K, Akt, and eNOS evoked by ischemia, whereas flutamide attenuated the effects of these protective mechanisms induced by RSE. RSE completely reversed the dropping of endogenous testosterone level induced by I/R injury. Flutamide plus RSE treatment not only abolished RSE’s effect but also produced a dramatic change on endogenous testosterone level after pretreatment and ischemia. Our results for the first time indicate that blocking androgen receptor abolishes the ability of Panax ginseng to protect the heart from myocardial I/R injury

Histological characterization and collagenous fibrosis in the hearts of young and intermediate-aged rats. magnification × 4 (A and B) or × 10 (C)is shown.

<p>A. Representative images showing the effects of RSE on histological changes in the heart after I/R or sham operation (hematoxylin and eosin stain). B. Representative images showing the effects of RSE through collagenous fibrotic staining in the heart after I/R or sham operation (Masson’s trichrome staining). Photomicrograph showing the cross section of cardiac tissues in rats treated with vehicle after the sham operation (<i>Top</i>), vehicle-treatment after I/R (<i>Middle</i>) and RSE-treatment after the I/R operation (<i>Bottom</i>). C. Representative heart section with myocardial injury histoscore of 4 (a, severe), a histoscore of 3 (b, moderate), a histoscore of 2 (c, mild), a histoscore of 1 (d, minimum), and 0 (e, nil). D. Scatter plot of histoscore. n = 4 rats in each group.</p

Effect of RSE on cardiac function.

<p>After 90 days, the rats were subjected to 30 min ischemia, followed by 90 min reperfusion. Left ventricular function was monitored at baseline and after reperfusion. (A) The data are shown as the means±SD, n = 6 rats/group. HR, heart rate; MAP, Mean arterial pressure; LVSP, left ventricular systolic pressure; LVEDP, left ventricular end-diastolic pressure; LV _max<i>dp/dt</i>, maximum first derivative of LVDP. *, <i>p</i> <0.05 vs. young, ^#, <i>p</i> <0.05 vs. vehicle-treated aged. Representative pressure-volume (P-V) loops obtained using the Millar P-V conductance catheter system from vehicle-treated young and intermediate-aged rats underwent sham operation (B), vehicle-treated young and intermediate-aged rats subjected to I/R(C), RSE-treated young and intermediate-aged rats subjected to I/R (D).</p

Western blot analysis of Sirt1 and Sirt3 protein expression in young and intermediate-aged rat hearts.

<p>Histone and Cox 4 were used as loading controls. The bar charts represent quantitative comparisons between the groups. Relative density was shown as the means± SD, n = 4/group. ^#<i>P</i><0.05, * <i>P</i><0.05.</p

Evaluation of myocardial cell apoptosis induced by I/R in young and intermediate-aged rat hearts.

<p>A. Left ventricular tissue was lysed and then the caspase3/7 activity was measured as Luminescence signal. B. Caspase-3 processing was evaluated by Western blotting. C. Bax and Bcl-2 protein expression in young and intermediate-aged rat hearts. β-actin were used as loading controls. The bar charts represent quantitative comparisons between the groups. Bax/Bcl-2 ratio calculated from the density analysis. D. Bax and Bcl-2 mRNA expression was evaluated by quantitative real-time PCR. The values were shown as the means± SD, n = 4/group. ^#<i>P</i><0.05, * <i>P</i><0.05, ^##<i>P</i><0.01, * *<i>P</i><0.01.</p

Outline of the experimental protocol.

<p>The experimental protocol used to evaluate the anti-aging effects of RSE against myocardial ischemia and reperfusion (I/R) injury. Young and intermediate-aged rats were fed RSE (80 mg/kg) or vehicle once daily for 90 days. After the last administration on the 90th day, the rats were subjected to LAD occlusion for 30 min ischemia, followed by 90 min reperfusion.</p