| OBJECTIVE: Based on the animal model of peri-menopausal ovariectomized female rats, this investigation was designed to systematically illustrate the possible cardioprotection mechanism and signal transduction pathway of SDG on injury of myocardial ischaemia/reperfusion(MIRI) in ovariectomized rats, trough detecting and comparing the changes of multiple important indexes in the level of molecule under the condition of the optimal dose of 50mg/kg b.w./day, which included the apoptosis and inflammatory injury and NOS and PI3K/Akt.METHODS: In this experiment of MIRI, there were 90 ten-week-olds in SPF grade randomized into sham-operated(SHAM) and ovariectomized(OVX) groups according to their weight. Furthermore, the latter one was divided into four groups: MIRI/SHAM, I/R, estradiol treated(EST) and SDG. In the group of SDG, ovariectomized rats were perfused with SDG dissolved by distillation water at a dose of 50mg/kg, while the EST selected a dose of 0.8mg/kg. However, the other two just used distillation water. After 8 weeks, different models of MIRI would be established based on respective experiments, in the process of which detailed methods were available as following: to determine the infarcted sizes in heart with Even`s Blue-TTC analysis, to detect the estrogen level, serum NO, e NOS and i NOS and c NOS in myocardium, TNF-α, IL-1β and IL-6 in serum by ELISA analysis, to test the expression of estrogen receptor α, phospho-PI3 K, phosphor-Akt, phosphor-e NOS, phosphor-BAD, and phosphor-Bcl2/Bax protein in myocardium through western blot analysis.RESULTS:1. There was a marked increase in myocardial infarction area in MIRI group than that of MIRI/SHAM. However, it sharply declined in the ovariectomized rats who were given SDG intervention. 2. By comparison with OVXsham group, the estrogen level in OVX obviously decreased, with weight gaining, uterus atrophying noticeably and uterus index reducing. On the contrary, these characters of the ovariectomized rats intervened by SDG changed well, whose weight gained slowly, estrogen level rose significantly, uterus atrophy relieved, and uterus index got higher. 3. According to the experimental observation, the levels of inflammatory factors in serum in MIRIgroup were higher than those in MIRI/SHAM, which included TNF-α, IL-1β and IL-6. But these indexes would be lower after SDG intervention. 4. It was found that the serum NO and the c NOS of myocardium decreased in MIRI group compared with MIRI/SHAM group. Nevertheless, the serum NO and c NOS went up in the context of SDG. 5. It indicated that the expression of Bcl2/Bax of myocardium in MIRI group was lower than that in MIRI/SHAM group, while the p-BAD expression was higher. But SDG intervention could convert them, which meant that the Bcl2/Bax expression would heighten and the p-BAD expression would lessened. It was also that the p-PI3 K and p-Akt and p-e NOS of myocardium were expressed at lower level in MIRI group than in MIRI/SHAM, but increased after SDG intervention. Finally, the expression of Era of myocardium in OVX group was less than in MIRI/SHAM, but became higher in SDG intervention.CONCLUSIONS: 1. SDG intervention could prominently improve the estrogen level in the serum of the ovariectomized rats, reduce the area of necrosis and apoptosis index of myocardium, decrease TNF-α, IL-1β and IL-6 and increase the serum NO at the same time, and also raise the level of c NOS. It could be deduced that the cardioprotection of SDG on injury of MIRI in ovariectomized rats is related to such factors as the increase of estrogenlevel and serum NO, the inhibition of apoptosis, the emergence of anti-inflammatory mediators and the energy of c NOS. 2. SDG intervention could evidently heighten the expression of estrogen receptor α, raise the proportion of phospho-PI3 K, phosphor-Akt, phosphor-e NOS, phosphor-Bcl2/Bax and phosphor-Bax protein in myocardium, and reduce phosphor-BAD protein simultaneously. As a result, it could be inferred that the cardioprotection mechanism of SDG on injury of MIRI in ovariectomized rats might lie in the process in which the estrogen receptor α touched off by SDG activates its anti-inflammatory and anti-apoptosis molecules to attenuate myocardial infarction and myocarditis and myocardial apoptosis to release the function of SDG through the signal transduction pathway provided by PI3K/Akt. |
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