Effects Of Puerarin On The AT1 MRNA And ACE2 MRNA Expression In Spontaneous Hypertension Rats

Objective: Studies showed Puerarin can reduce angiotensinⅡlevel in plasma and blood pressure in human and some animals, but the effects of puerarin on angiotensinⅡtype 1 receptor and angiotensin-converting enzyme 2 still has not been reported. So we will evaluate those by RT—PCR.Method: 12-week-old male SHRs were randomly divided into four groups: control group (normal saline), Verapamil group (6mg/kg.d), low dosage group of puerarin(100mg/kg.d), high dosage group of puerarin(200mg/kg.d). All drugs were given by Intraperitoneal injection for three weeks. Total RNA was extracted from heart, aorta and kidney tissue, respectively. The level of AT1 mRNA, ACE2 mRNA andβ-actin mRNA expression was examined by RT-PCR. the relatively expression of ACE2 or AT1 mRNA was defined as ratio value of the average optical density of ACE2 mRNA or AT1 mRNA to that ofβ-actin mRNA. One-way ANOVA followed by the 2-tailed student t test was used for comparing the differences between the groups, linear regression analysis was used for determining the relation of ACE2 mRNA to AT1 mRNA. Data was analysed by SPSS 13.0.Result: 1. The expression of ACE2 mRNA: ACE2 mRNA expressions were detected only in few samples of aorta because of low expression of it in aorta, so the data of ACE2 mRNA expressions in aorta has not been statistically analyzed. In heart, the expression of ACE2 mRNA in low dosage group of puerarin decreases as compared to that of control group , P＜0.05. There are no significant differences among high dosage group of puerarin, Verapamil group and control group, in kidney, ACE2 mRNA expression of high dosage group of puerarin increases as compared to that of control group and low dosage group of puerarin, P＜0.05. There are no significant differences between other groups.2. The expression of AT1 mRNA: In aorta, AT1 mRNA expression of all groups has no statistically significance. In heart, the expression of AT1 mRNA in low dosage group of puerarin decreases as compared to that of control group, P＜0.05. There are no significant differences among high dosage group of puerarin, Verapamil group and control group. In kidney, Ar1 mRNA expression of high dosage group of puerarin increases as compared to that of control group, P＜0.05. There are no significant differences between other groups.3. The relationship between the AT1 mRNA expression and the ACE2 mRNA expression: Linear regression analysis was carried out, coefficient of regression has statistically significance, P＜0.0005. coefficient of correlation is 0.56, the slope is 0.758. It indicate that there has positive Linear relationship between the AT1 mRNA expression and the ACE2 mRNA expression.Conclusions: 1. The target-organs of puerarin vary from dosages. In low dosage group of puerarin, AT1 mRNA expression level decreases in heart, while in high dosage group of puerarin, AT1 mRNA expression level increases in kidney.2. The decreased level of AT1 mRNA expression induced by low dosage of puerarin, may play an important role in the inhibition of myocardial hypertrophy and the reduction of myocardial infarction size.3. There has Positive linear relationship between ACE2 mRNA expression and AT1 mRNA expression. It seems that AT1 receptor can regulate ACE2 expression in a positive feed-back manner.