OBJECTIVE

To observe the effects of acupuncture at "Kongzui" (LU 6) and "Yuji" (LU 10) on the latent period of inducing asthma, pulmonary function and the expression of endothelin-1 (ET-1) and metallothionein-2 (MT-2) in asthma rats, and to explore the possible mechanism of acupuncture in alleviating airway smooth muscle spasm and improving the acute attack of asthma.

METHODS

A total of 40 male SD rats of SPF-grade were randomly divided into a normal group, a model group, a medication group and an acupuncture group, 10 rats in each group. Except for the normal group, ovalbumin sensitization method was used to establish the asthma model in the other 3 groups. Salbutamol nebulization was adopted in the medication group, while acupuncture was applied at bilateral "Kongzui" (LU 6) and "Yuji" (LU 10) in the acupuncture group. The intervention was given once a day for 14 days in the two groups. The latent period of inducing asthma and pulmonary function were observed, the levels of ET-1 and tumor necrosis factor (TNF)-α in serum and bronchoalveolar lavage fluid (BALF) were detected by ELISA method, the morphology of the airway was observed by Masson staining, the ultrastructure of the airway smooth muscle was observed by transmission electron microscopy, the mRNA and protein expression of ET-1 and MT-2 in lung tissue was detected by real-time PCR and Western blot methods.

RESULTS

Compared with the normal group, in the model group, the latent period of inducing asthma was shortened (<0.01); the airway resistance (RL) was increased while the dynamic compliance (Cdyn) was decreased (<0.01, <0.05); the levels of ET-1 and TNF-α in serum and BALF were increased (<0.01); collagen fibers and collagen depositions were found around the bronchi, airway smooth muscle was thickened, the cell damage was severe and mitochondria were swollen; the mRNA and protein expression of ET-1 was increased while the mRNA and protein expression of MT-2 was decreased (<0.01). Compared with the model group, in the acupuncture group, the latent period of inducing asthma was prolonged (<0.05), the RL was decreased while the Cdyn was increased (<0.01, <0.05). Compared with the model group, in the medication group and the acupuncture group, the levels of ET-1 and TNF-α in serum and BALF were decreased (<0.01, <0.05); collagen fibers and collagen depositions around the bronchi were reduced, the thickened airway smooth muscle was lightened, the cell damage was improved; the mRNA and protein expression of ET-1 was decreased while the mRNA and protein expression of MT-2 was increased (<0.01). Compared with the medication group, the mRNA expression of MT-2 was increased in the acupuncture group (<0.05).

CONCLUSION

Acupuncture at "Kongzui" (LU 6) and "Yuji" (LU 10) can improve the pulmonary function and alleviate the airway smooth muscle spasm in rats with asthma. Its mechanism may be related to the down-regulation of ET-1 expression and up-regulation of MT-2 expression.