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Neural pathways of cardiovascular depressor reflex during gastric distension and its modulation by electroacupuncture
Author(s) -
Hsiao AnFu,
TjenALooi Stephanie,
Zhou Wei,
Li Peng,
Cabatbat Ranier,
Longhurst John C
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.737.23
Subject(s) - electroacupuncture , gastric distension , medicine , reflex , vagotomy , baroreceptor , baroreflex , vagus nerve , microinjection , endocrinology , anesthesia , vagovagal reflex , nucleus ambiguus , ganglionectomy , medulla oblongata , heart rate , blood pressure , stimulation , stomach , central nervous system , acupuncture , alternative medicine , pathology
Mild mechanical gastric distension (GD) frequently evokes a decrease in blood pressure and bradycardia. We hypothesized that the GD‐induced cardiovascular depressor reflex is transmitted through both sympathetic and parasympathetic afferent pathways. We also hypothesized that it can be modulated by electroacupuncture (EA) and is mediated by caudal ventral lateral medulla (cVLM) and nucleus ambiguus (NA). Sprague‐Dawley rats were anesthetized, ventilated, and their mean arterial blood pressures (MAP) and heart rates (HR) monitored. Repeated balloon inflation of the stomach every 10 minutes to 15–20 mmHg gastric wall tension induced consistent falls in MAP and HR. This inhibitory response was reversed by chemical denervation of celiac ganglia and intra‐abdominal vagal nerves with 0.1mL of 1% lidocaine, suggesting that the decreased MAP was mediated by both the withdrawal of sympathetic tone and increased parasympathetic tone. Similarly, the reduced HR was reversed after vagotomy and celiac ganglionectomy. Bilateral stimulation with EA at cardiovascular acupoints P5‐6 for 30 min significantly decreased the depressor response. This modulation lasted for 50 min. Unilateral microinjection of atropine into cVLM immediately after termination of EA reversed the inhibition by EA, whereas microinjection of normal saline into cVLM did not reverse it. Microinjection of gabazine into the NA reversed the inhibition by EA. These data suggest that GD activates both sympathetic and vagal afferents to evoke reflex cardiovascular sympatho‐ and parasympatho‐inhibition through the cVLM and NA respectively. EA attenuates the cardiovascular depressor reflex through a cholinergic mechanism in the cVLM and a gabanergic mechanism in the NA.