Presentation Title

Role of Angiotensin-(1-7) in Electroacupuncture Inhibition on Salt-sensitive Hypertensive Rats

Faculty Mentor

Stephanie Tjen-A-Looi

Start Date

18-11-2017 11:15 AM

End Date

18-11-2017 11:30 AM

Location

9-271

Session

Bio Sciences 2

Type of Presentation

Oral Talk

Subject Area

health_nutrition_clinical_science

Abstract

Many people suffer from hypertension and are administered drugs to manage it; however, drugs are frequently accompanied by adverse effects. Electroacupuncture (EA) can be an alternative method to treating those with high blood pressure (BP), the mechanism of which remains unclear. In the present study, we hypothesize that EA acts through the angiotensin system (1-7) in the paraventricular nucleus or PVN to decrease BP in salt-sensitive rats with mild to moderate hypertension (140 -160 mmHg systolic blood pressure (SBP); 100-110 mmHg diastolic blood pressure (DBP)). For this study, EA was performed on salt-sensitive rats with salt-induced hypertension (SIH). Eighteen rats were put into one of 4 groups: EA-SIH (EA used for SIH rats), sham-EA-SIH (needles, but no electricity applied to SIH rats), untreated SIH (no needles at all in SIH rats), and salt sensitive rats on a normal diet. The rats received their respective treatment for 4.5 weeks after the salt-sensitive rats had been placed on a high salt diet for 3.5 weeks. EA was conducted for 30 minutes twice weekly and applied bilaterally at acupoints ST36-37, which overly the deep peroneal nerves. BP decreased in SIH rats after EA treatment. Microinjection of angiotensin-(1-7) into the PVN of sham EA rats lowered their blood pressure. Microinjection of angiotensin-(1-7) (Ang-(1-7)) receptor antagonist, A-779, into the PVN of EA rats raised blood pressure, reversing the EA inhibitory effects on SIH while a saline control did not influence effect of EA. This suggests that EA may act through the Ang-(1-7) system in the hypothalamus to decrease BP in SIH rats. The finding also suggested that EA reduced hypertension through the Ang-(1-7) system in the PVN. Although further experiments should be conducted, this shows potential for EA to be a non-pharmacological approach in decreasing BP and can possibly lead way to clinical studies.

Summary of research results to be presented

Hypertensive rats subjected to EA over a 4.5 week period showed a sustained decrease in SBP. Sham EA rats and control hypertensive rats had a continuous increase in blood pressure, while normotensive rats had a relatively constant BP.

Microinjection of 50-75 nL of angiotensin (1-7) into the PVN of sham EA-rats was performed to determine whether angiotensin (1-7) is important in keeping blood pressure down in these rats. After the injection of angiotensin (1-7) into the sham-EA rats, the blood pressure in these rats decreased.

Microinjection of 50-75 nL of A-779, an angiotensin (1-7) receptor blocker, into the PVN of EA-treated rats, was performed to determine whether the effects of EA were facilitated by the angiotensin (1-7) system in the brain. After the injection of A-779 into the EA rats, SBP and DBP both increased.

This experiment may imply that EA is capable of decreasing BP in salt-sensitive hypertensive rats through the angiotensin (1-7) system in the brain in areas such as the PVN, which affects sympathetic neuronal activity and is involved with blood pressure regulation. Although further experiments should be conducted, especially with regards to the role of other neurotransmitter systems, this shows potential for EA to be a non-pharmacological approach in decreasing BP.

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Nov 18th, 11:15 AM Nov 18th, 11:30 AM

Role of Angiotensin-(1-7) in Electroacupuncture Inhibition on Salt-sensitive Hypertensive Rats

9-271

Many people suffer from hypertension and are administered drugs to manage it; however, drugs are frequently accompanied by adverse effects. Electroacupuncture (EA) can be an alternative method to treating those with high blood pressure (BP), the mechanism of which remains unclear. In the present study, we hypothesize that EA acts through the angiotensin system (1-7) in the paraventricular nucleus or PVN to decrease BP in salt-sensitive rats with mild to moderate hypertension (140 -160 mmHg systolic blood pressure (SBP); 100-110 mmHg diastolic blood pressure (DBP)). For this study, EA was performed on salt-sensitive rats with salt-induced hypertension (SIH). Eighteen rats were put into one of 4 groups: EA-SIH (EA used for SIH rats), sham-EA-SIH (needles, but no electricity applied to SIH rats), untreated SIH (no needles at all in SIH rats), and salt sensitive rats on a normal diet. The rats received their respective treatment for 4.5 weeks after the salt-sensitive rats had been placed on a high salt diet for 3.5 weeks. EA was conducted for 30 minutes twice weekly and applied bilaterally at acupoints ST36-37, which overly the deep peroneal nerves. BP decreased in SIH rats after EA treatment. Microinjection of angiotensin-(1-7) into the PVN of sham EA rats lowered their blood pressure. Microinjection of angiotensin-(1-7) (Ang-(1-7)) receptor antagonist, A-779, into the PVN of EA rats raised blood pressure, reversing the EA inhibitory effects on SIH while a saline control did not influence effect of EA. This suggests that EA may act through the Ang-(1-7) system in the hypothalamus to decrease BP in SIH rats. The finding also suggested that EA reduced hypertension through the Ang-(1-7) system in the PVN. Although further experiments should be conducted, this shows potential for EA to be a non-pharmacological approach in decreasing BP and can possibly lead way to clinical studies.