Electro-acupuncture regulates the cholinergic anti-inflammatory pathway in a rat model of chronic obstructive pulmonary disease

Objective: Acupuncture has a definite therapeutic effect on chronic obstructive pulmonary disease（COPD）, and the cholinergic anti-inflammatory pathway（CAP） has been shown to be involved in regulation of inflammation. In this study, we investigated whether electro-acupuncture（EA） affects the CAP in COPD.Methods: Sprague-Dawley rats were induced into COPD through exposure to cigarette smoke combined with lipopolysaccharide. EA treatment was applied at Zusanli（ST36） and Feishu（BL13） points for 30 min/d for 7 d. Seventy-two rats were randomly divided into six study groups, including normal, normal + EA,normal + α-bungarotoxin（a-BGT）（the antagonist of the nicotinic acetylcholine receptor a7 subunit（a7 nAChR）） + EA, COPD, COPD + EA, and COPD + α-BGT + EA. Lung function, pathology and vagus nerve discharge were tested. The levels of acetylcholine（ACh）, acetylcholinesterase（AChE）, interleukin-6（IL-6） and tumor necrosis factor-a（TNF-a） in bronchoalveolar lavage fluid（BALF） and lung tissue were measured by enzyme-linked immunosorbent assay. The mRNA and protein expression and immunoreactivity of a7 nAChR and its postreceptor inflammation signal pathway, including janus kinase 2（JAK2）, signal transducers and activators of transcription 3（STAT3）, nuclear factor-KB（NF-κB）, were observed by quantitative reverse transcription-polymerase chain reaction, Western blot and immunohistochemistry.Results: Compared with normal rats, there were a significant decline in lung function and discharge of the vagus nerve（P ＜ 0.01）, a marked sign of lung inflammation and an increase of ACh, AChE, IL-6 and TNF-a level in BALF or lung tissue（P ＜ 0.05, P ＜ 0.01） and higher expression of a7 nAChR, JAK2, STAT3 and NF-κB（P＜0.05, P＜0.01） in the COPD rats. In rats receiving EA, the lung function and vagal discharge were enhanced（P ＜ 0.01）, lung inflammation was improved and the levels of ACh, AChE, IL-6 and TNF-a were decreased（P＜0.01）. Further, the expression of a7 nAChR, JAK2, STAT3 and NF-κB was downregulated（P ＜ 0.05, P ＜ 0.01）. However, the above effects of EA were blocked in rats injected with α-BGT（P ＜ 0.01）.Conclusion: EA treatment can reduce the lung inflammatory response and improve lung function in COPD, which may be related to its involvement in the regulation of CAP.