Presentation Title

Moxibustion Modifies Mean Arterial Pressure in Rats through Peripheral Transient Receptor Potential Vanilloid Type 1 and Hypothalamic Paraventricular Nucleus

Faculty Mentor

Tjen-a-looi, Stephanie

Start Date

18-11-2017 11:30 AM

End Date

18-11-2017 11:45 AM

Location

9-271

Session

Bio Sciences 2

Type of Presentation

Oral Talk

Subject Area

health_nutrition_clinical_science

Abstract

Rostral ventrolateral medulla (rVLM) and paraventricular nucleus (PVN) in the brain are known to regulate blood pressure. Electroacupuncture (EA) and manual acupuncture (MA) modulate pressor responses in rostral ventrolateral medulla (rVLM). Stimulation of acupoints P6 and ST36 activates PVN and rVLM during EA and MA. Transient receptor potential vanilloid type 1 (TRPV1) is crucial in MA inhibition of reflex increase in blood pressure, but not EA. TRPV1 is a heat-sensitive receptor (temperature greater than 42℃) that locates on sensory neuronal tissue, which can be activated by capsaicin and mechanosensitive stimuli. Thus, we hypothesized that ST36 acupoint stimulated by moxibustion decreased reflex hypertension through peripheral TRPV1 and opioids in PVN. The rats were anesthetized, intubated, cannulated and monitored for normal body temperature, and blood gasses. Craniotomy allowed access to the PVN and microinjection of opioid antagonist, Naloxone and vehicles into the PVN. We observed that ST36 acupoint stimulated by moxibustion reduced sympathetic outflow and blood pressure, which increased again when TRPV1 antagonist was delivered into the acupoint or Naloxone was microinjected into PVN. The data demonstrated that ST36 acupoint stimulation with moxibustion lowered reflex hypertension through heat-activated TRPV1 and opioid system in PVN.

Key Words:

Blood pressure

Moxibustion

Transient receptor potential vanilloid type 1 (TRPV1)

Gastric distention

Acupoint (ST36)

Opioid in paraventricular nucleus (PVN)

Summary of research results to be presented

Effects of Point Specific Stimulation with Moxibustion.

Repeated stimulation of gastric afferents by gastric distention every 10 min increased blood pressure consistently in rats. Acupoint ST36 overlying deep peroneal nerves stimulated by heat (43-46℃) generated by moxibustion for 30 min within a 1 cm distance from the skin, reduced mean arterial pressure (MAP) of reflexly induced hypertension. Equivalent stimulation of acupoint G39 overlying superficial nerves did not influence the change in MAP in rats.

Effects of Temperature Sensitive Moxibustion and Receptor Activation.

Stimulation of acupoint ST36 noticeably decreased change in MAP when stimulated within a 1cm distance away from the rats at 43-46℃, but had no effect when stimulated at distances further than 2cm, which generated heat below 40℃. The temperature sensitive receptor TRPV1 activated at 43℃ is located in sensory nerve endings in the area of ST36. A TRPV1 antagonist, Iodoresiniferatoxin (Iodo-RTX; 0.1 mM), was used to block TRPV1 at acupoint ST36. Microinjection of Iodo-RTX into acupoint ST36 resulted in reversal of moxibustion effect. On the other hand, microinjection of its vehicle, 5% dimethylsulfoxide (DMSO) did not affect the blood pressure lowering effect of moxibustion.

Opioid Receptor Antagonist in Hypothalamic Central Processing.

Microinjection of 1mM Naloxone (50nl, a nonspecific opioid receptor antagonist) into PVN, reversed the blood pressure lowering effect of moxibustion. Conversely, microinjection of its vehicle, saline, into PVN during the effect of moxibustion did not reverse the decreased cardiovascular reflex responses.

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Nov 18th, 11:30 AM Nov 18th, 11:45 AM

Moxibustion Modifies Mean Arterial Pressure in Rats through Peripheral Transient Receptor Potential Vanilloid Type 1 and Hypothalamic Paraventricular Nucleus

9-271

Rostral ventrolateral medulla (rVLM) and paraventricular nucleus (PVN) in the brain are known to regulate blood pressure. Electroacupuncture (EA) and manual acupuncture (MA) modulate pressor responses in rostral ventrolateral medulla (rVLM). Stimulation of acupoints P6 and ST36 activates PVN and rVLM during EA and MA. Transient receptor potential vanilloid type 1 (TRPV1) is crucial in MA inhibition of reflex increase in blood pressure, but not EA. TRPV1 is a heat-sensitive receptor (temperature greater than 42℃) that locates on sensory neuronal tissue, which can be activated by capsaicin and mechanosensitive stimuli. Thus, we hypothesized that ST36 acupoint stimulated by moxibustion decreased reflex hypertension through peripheral TRPV1 and opioids in PVN. The rats were anesthetized, intubated, cannulated and monitored for normal body temperature, and blood gasses. Craniotomy allowed access to the PVN and microinjection of opioid antagonist, Naloxone and vehicles into the PVN. We observed that ST36 acupoint stimulated by moxibustion reduced sympathetic outflow and blood pressure, which increased again when TRPV1 antagonist was delivered into the acupoint or Naloxone was microinjected into PVN. The data demonstrated that ST36 acupoint stimulation with moxibustion lowered reflex hypertension through heat-activated TRPV1 and opioid system in PVN.

Key Words:

Blood pressure

Moxibustion

Transient receptor potential vanilloid type 1 (TRPV1)

Gastric distention

Acupoint (ST36)

Opioid in paraventricular nucleus (PVN)