[Parasympathetic innervation contributes to the increase of survival rate and anti-inflammatory effect of electroacupuncture at "Ciliao"(BL32) in rats with lethal endotoxemia].

ABSTRACT

OBJECTIVE: To observe the effect of electroacupuncture (EA) at "Ciliao" (BL32) on the survival rate and serum inflammatory cytokine levels in rats with lethal endotoxemia, and to explore its parasympathetic mechanism in suppressing severe systemic inflammation. METHODS: A total of 82 male SD rats were used in the present study. In the first part of this study, 40 rats were randomized into model and EA-BL32 groups (n=20/group). The endotoxemia model was established by intraperitoneal injection of lethal amount of lipopolysaccharide (LPS, 10 mg/kg). EA (30 Hz, 6 mA) was applied to bilateral BL32 for 30 min before and after LPS injection. The survival rate in 7 days was then recorded. In the second part of this study, 42 rats were randomized into normal control, model, EA-BL32, EA-BL32+cervical vagotomy, EA-BL32+truncal (subdiagrammatical) vagotomy and EA-BL32+pelvic neurectomy groups (n=7/group). The endotoxemia model was established by intraperitoneal injection of LPS (6 mg/kg) 30 min after the neurectomy. Rats of the control group received intraperitoneal injection of 6 mg/kg saline. EA with the same parameters mentioned above was applied to bilateral BL32 for 30 min before and after LPS injection. Blood sample was collected from the abdominal aorta 3 h after LPS injection for detecting the levels of TNF-α, IL-1ß and IL-6 by ELISA. RESULTS: ① The EA survival rate was 25% in the model group and 60% in the EA -BL32group, being significantly improved after EA (P<0.05). ② The contents of serum TNF-α, IL-1ß and IL-6 were significantly higher in the model group than those in the control group (P<0.000 1). After EA intervention, and compared with the model group, the levels of TNF-α, IL-1ß and IL-6 were significantly decreased in the EA-BL32, EA-BL32+cervical vagotomy, EA-BL32+truncal vagotomy and EA-BL32+pelvic neurectomy groups (P<0.000 1，P<0.01). After neurectomy and compared to the EA-BL32 group, the contents of TNF-α and IL-6 in the EA+cervical vagotomy and EA+pelvic neurectomy groups, IL-1ß in the EA+pelvic neurotomy group were significantly higher (P<0.0000 1, P<0.05), suggesting an elimination of EA effects after neurectomy. No significant differences were found among the 3 neurectomy groups in the levels of TNF-α, IL-1ß and IL-6 (P>0.05). CONCLUSION: EA of BL32 can improve the survival rate and attenuate the level of inflammatory cytokines in rats with lethal endotoxemia, which is closely related to the intact of parasympathetic pathway including the vagus nerve and pelvic nerve.