| Objective We have investigated the hypotensive effect of different doses of Dendrobium officinale flower in SHR rats,and detected the expression level of several genes RAAS system-related,which primarily reveals the antihypertensive mechanism of Dendrobium officinale flower.Methods(Ⅰ)Experimental animals and groups:32 SHR rats of 8-week-old,half males and half females,whose mean weight 177.7± 15.91 g,were randomly divided into four groups(n=10),including model group,low-dose dendrobium officinale flower group,middle-dose dendrobium officinale flower group,high-dose dendrobium officinale flower group,four groups.16 normal Wistar rats of 8-week-old,half males and half females,whose mean weight 213.3±42.45 g,were divided into control group and four groups of normal middle-dose group,two groups(n=8).(Ⅱ)experimental period:The whole experiment was divided into two phases:In the first phase,rats were treated with medication for 8 weeks,then drug withdrawal for 1 week.In the second phase,rats were treated with medication for7 weeks(dosage doubled),observing 2 weeks after drug withdrawal.(Ⅲ)Experiment methods:In the first phase,rats in the normal control and model group were given normal saline,normal middle-dose group were given dendrobium officinale flower(1.5 g/kg crude drugs)by intragastric administration.High-dose,middle-dose,low-dose dendrobium officinale flowergroup,were given dendrobium officinale flower(4.5 g/kg、1.5 g/kg、0.5 g/kg crude drugs respectively)by intragastric administration.The gavage volume was lml/kg.In the second phase,the normal control and model group were given normal saline.Normal middle-dose group were given dendrobium officinale flower 3.0g/kg crude drugs by intragastric administration.High-dose,middle-dose and low-dose dendrobium officinale flower group,were given dendrobium officinale flower 9.0 g/kg、3.0 g/kg、1.0 g/kg crude drugs respectively by intragastric administration.The total gavage volume was 1.0 ml/kgThe first phase,blood pressure(SBP and DBP),Heart rate(HR),Body weight(BW)were measured 1 time a week.The first phase of thel hour after last administration in the experiment.Groups rats shearing tail take the artery blood to detective angiotensin Ⅱ(Ang Ⅱ)content.In addition to taking three male rats from each the normal control group,model group,High-dose group.Taking the liver and lung two Organizations,used to detect the expression of liver angiotensin(AGT)mRNA and lung in angiotensin converting enzyme(ACE)mRNA.The second phase,before medication(close to 24 hours after medication),after 1h medication,after 2h medication,blood pressure is measured every week.The second phase of the last administration after 1h in the experiment.The normal control group,model group,High-dose group were taken blood by abdominal aortic method.The rest three groups were taken Blood by shear tail method to detection the content of Ang Ⅰ,Ang Ⅱ,ACE,PRA and ALD.In addition,high dose group,model group,normal control group all out of liver,lung,kidney and other organs.To be detected the expression of liver in the angiotensin(AGT)mRNA and lungs of angiotensin converting enzyme(ACE)mRNA and Renin(Renin)mRNA in the kidney and aldosterone synthase(CYP11B2)mRNA.Results:The first stage:prior treatment,the group had no significant difference,the normal control group and the normal middle dose group had no significant difference.As rats age aging,pressure of each SHR group raised was completed.Dendrobium officinale flower high-middle dose group blood pressure increasing amplitude was significantly lower than the model group,and high dose group most significant.Blood pressure of the high dose group before treatment had no significant difference.From treat to drug withdrawal a week,were significantly lower than the concurrent model group(P<0.05～0.01).The high dose group treat blood pressure 8 week 181.3±11.90/148.2±9.19 mmHg,the model group treat blood pressure 8 week 209.2±10.66/162.0±3.67mmHg.The high dose group was significantly lower than the concurrent middle dose group in the first week,the third week,the fifth week,the sixth week,the seventh week and the eighth week after the drug use and 3 days after drug withdrawal(P<0.05～0.01);The high dose group was significantly lower than the concurrent low dose group in the first week,the third week,until 3 days after drug withdrawal(P<0.01);The middle dose group was significantly lower than the concurrent fourth group in the week,the seventh week after the drug use and 1 week after drug withdrawal(P<0.05).The middle dose group treat blood pressure 8 week 198.1±6.54/156.6±6.97 mmHg.In addition to the low dose group blood pressure is significantly lower than model group after 1 week drug withdrawal,there were no significant difference with model group in the rest of time(P>0.05).The low dose group treat blood pressure 8 week 206.3±7.57/161.1±3.80 mmHg.From treatment to 1 week after drug withdrawal,the normal control group and the normal middle dose group blood pressure had no significant difference,were lower than the concurrent model group,compared with the extremely significant difference(P<0.01)blood pressure of each SHR group raised after drug withdrawal was completed.The second stage:blood pressure of the high dose group was significantly lower than the model group in the whole stage(P<0.01),the high dose group treat blood pressure a week 190.5±6.85/145.3±6.12 mmHg,the model group treat blood pressure a week 217.6±9.50/171.7±3.72 mmHg,the high dose group treat blood pressure 7 week 205.2±8.91/150.3±9.36 mmHg,the model group treat blood pressure 7 week 219.7±8.03/171.8± 1.62 mmHg;The high dose group was significantly lower than the middle dose group in the second week,the third week,the fifth week,and the eighth week after the drug use(P<0.05～0.01),the middle dose group treat blood pressure 7 week 215.5±8.22 mmHg/159.1±4.62 mmHg;the first to seventh week after the drug use,blood pressure of the high dose group was significantly lower than the low dose of group(P<0.01),the low dose of irradiation treat blood pressure 7 week 222.7±9.83/170.8±3.63 mmHg。The middle dose group is significantly lower than the model group in the second week,the third week,the forth week,the fifth week,and the sixth week after the drug use(P<0.05～0.01),and in the forth week,the fifth week,and the sixth week it is significantly lower than the low dose of group.The blood pressure of the low dose of group in the second week 209.5±5.45/163.0±6.00mmHg was significantly lower than the model group 220.3±5.06/170.2±4.34 mmHg(P<0.01),The rest of the time had no difference.The normal control group and the normal middle dose group are significantly lower than each SHR group,and there was no significant difference in the normal control group and the normal middle dose group,Blood pressure of each SHR group raised after the treatment was completed.The results show that prolonged period of treatment may improve the efficacy of decreased DBP.Blood pressure of the high dose group was significantly lower than the model group after the drug use an hour in every week of the second stage(P<0.01);the first times amount administration four weeks and six weeks,the high dose group was significantly lower than the middle dose group(P<0.05～0.01)and that significantly lower than the low dose of group(P<0.01)after times amount administration two weeks to seven weeks.In addition to the first time times amount administration an hour,blood pressure of the middle dose group was significantly lower than the model group(P<0.01);Among them,the middle dose group after times amount administration 1h of two weeks,four weeks,and seven weeks the blood pressure was significantly lower than the low dose of group(P<0.05～0.01),the low dose of group of first times amount administration four weeks and five weeks,after the drug use an hour,the blood pressure was significantly lower than the model group(P<0.05～0.01).The blood pressure of each SHR group raised after the drug use 2 hours,all about to the lever before drug use the day.The normal control group and the normal middle dose group had no significant difference after the drug use one hour and two hours.(2)HR:heart rate of the normal control group and the normal middle dose group had no significant difference,decreasing tendency was in each SHR group,but there was no statistical significance.(3)BW:normal rats all higher than each SHR group,treatment group and the model group all had no significant difference.(4)Content of AngⅠ、AngⅡ、ACE、PRA、ALD:The first stage:in the plasma of normal rats,the content of AngⅡwas significantly higher than each SHR group(P<0.01),the two normal control group had no significant difference;in each SHR group,low dose of group was higher than model group,high dose group was lower than model group,but there was no statistical significance.The second stage:the content of AngⅠ in the SHR model group was significantly higher than the high dose group and model group(P<0.05).The content of AngⅡ in the second stage was significantly lower than the first stage,but had no significant difference with the trend.Normal rats was higher than SHR ones,middle dose group was significantly higher than high dose group、low dose of group and model group(P<0.05).The content of ACE of the six groups in the plasma had no significant difference.PRA of normal rats was higher than SHR ones,and model group was significantly lower than normal control group(P<0.05),model group was significantly higher than the low dose group and model group(P<0.05);The content of ALD in the model group was higher than the other five groups,but it had no significant difference.(5)Expression of AGT mRNA、ACE mRNA、Renin mRNA and CYP11B2 mRNA:The first stage:Expression of liver AGT mRNA in high dose group was significantly higher than model group(P<0.05);higher than normal control group,but not significant.Expression of lungs ACE mRNA in high dose group was significantly lower than model group,and significantly higher than normal control group(P<0.05);Expression of lungs ACE mRNA in model group significantly higher than normal control group(P<0.01)and high dose group(P<0.05).The second stage:Expression of liver AGT mRNA in high dose group was higher than model group,but not significant.Expression of lungs ACE mRNA in high dose group was lower than model group,and higher than normal control group,but there was no statistical significance.Kidney Renin mRNA in high dose group was lower than model group and normal control group,but it had no significant difference.Model group and normal control group also had no significant difference;Expression of Kidney CYP11B2 mRNA in high dose group was significantly lower than model group(P<0.01),and higher than normal control group,but it had no significant difference;Model group was significantly higher than normal control group(P<0.01).Conclusion:1.Dendrobium officinale flower aqueous extract can significantly lower The blood pressure of the SHR rats,and antihypertensive effect increases with dose increases.Crude drug of dendrobium officinale flower 1.0 g/kg weight have certain antihypertensive effect;crude drug 3.0 g/kg-9.0 g/kg weight have significant antihypertensive effect.2.Dendrobium officinale flower aqueous extract have decreasing tendency to high HR SHR rats,but it had no significant difference.It has no function to reducing HR of normal rats.3.Dendrobium officinale flower aqueous extract have no function to BW of normal Wistar and SHR rats.4.Dendrobium officinale flower aqueous extract have no effect on the blood pressure of normal Wistar rats with crude drug 1.5 g/kg and 3.0 g/kg weight.5.Dendrobium officinale flower aqueous extract of crude drug 4.5 g/kg weight(high dose group in The first stage)can significantly lower the expression lever of lungs ACE mRNA of Wistar rats after treat eight weeks.Hypotensive effect of dendrobium officinale flower aqueous extract to SHR rats still needs further research. |
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