Mechanism of electroacupuncture at acupoints of the lung meridian through PKA/PKC regulation of TRPV1 in chronic cough after lung surgery in guinea pigs

BACKGROUND: Acupuncture has achieved good results in the treatment of cough, asthma, chronic obstructive pulmonary disease (COPD) and other lung diseases, but the mechanism associated with acupuncture in the treatment of chronic cough induced by lung surgery is unknown. We investigated whether acupuncture therapy could improve the symptoms of chronic cough after lung surgery through cyclic-AMp dependent protein kinase A (PKA)/cyclic-AMp dependent protein kinase C (PKC) regulation of the transient receptor potential vanilloid-1 (TRPV1) signaling pathway. METHODS: The guinea pigs were divided into 5 groups: the Sham operation Group (Sham), the Model Group (Model), the Electroacupuncture + Model Group (EA + M), the H89 + Model Group (H89 + M) and the Go6983 + Model Group (Go6983 + M). The effect of treatment was determined by measuring cough symptoms (number of coughs/cough incubation period) as the outcome criterion. The levels of inflammatory cytokines in bronchoalveolar lavage fluid (BALF) and blood were determined by enzyme-linked immunosorbent assays (ELISA). Lung tissue was stained with hematoxylin and eosin (H&E). The expression of p-PKA, p-PKC and p-TRPV1 proteins was measured by Western blotting. The mRNA levels of TRPV1, Substance P (SP), calcitonin gene-related peptide (CGRP) and neurokinin-1R (NK1R) were measured by real-time polymerase chain reaction (RT-PCR). RESULTS: Acupuncture significantly reduced the cough frequency and prolonged the cough latency of chronic cough in guinea pigs after lung surgery. In addition, acupuncture reduced the damage to lung tissue. The levels of inflammatory cytokines decreased in all treatment groups, the expression levels of p-PKA, p-PKC and p-TRPV1 were significantly inhibited and the mRNA levels of TRPV1, SP, CGRP and NK1R decreased significantly after acupuncture treatment. CONCLUSIONS: Acupuncture therapy ameliorated chronic cough in guinea pigs after lung surgery by regulating the TRPV1 signaling pathway via PKA/PKC. Our results showed that acupuncture may be an effective treatment of chronic cough after lung surgery, and also clarified the potential mechanism, which provides a theoretical basis for the clinical treatment of patients with chronic cough after lung surgery.