Protective effect of electro-acupuncture on liver ischemia-reperfusion injury in rats

Liver ischemia-reperfusion injury is an important clinical complication in which excessive inflammation is a key factor; however, few studies have provided effective means of its regulation. As previous studies suggested that electro-acupuncture (EA) is able control excessive inflammation, the present study aimed to explore its effects on liver ischemia-reperfusion injury in experimental rats. The animals were randomly divided into surgery and sham groups, which were further divided into four sub-groups, including a non-treatment (NT), a non-point acupuncture (NPA), the non-selective nicotinic acetylcholine receptor (AChR) agonist 1,1-dimethyl-4-phenyl L-pioperazinium iodide (DMPPI) and an EA group. The alanine aminotransferase (ALT), serum cytokine and myeloperoxidase (MP) levels and the tissue pathology were evaluated after 90 min of ischemia followed by a 4, 8 or 24 h reperfusion. The results demonstrated that EA and DMPPI suppressed serum ALT elevation at 4 and 8 h reperfusion, whereas NPA did not. I/R induced hepatocellular necrosis, and cytoplasmic vacuolization and sinusoidal congestion was ameliorated by EA treatment after an 8 and 24 h reperfusion. In addition, EA also inhibited liver neutrophil accumulation, evidenced by a decreased MPO level at 8 h reperfusion. EA also suppressed the release of serum inflammatory factors TNF-α and IL-6 for the duration of reperfusion. However, little influence on IL-10 was observed. Mechanistically, vagus block by subphrenic vagotomy or mecamylamine hydrochloride abolished EA effect on liver damage, neutrophil accumulation and inflammatory factor release. In conclusion, it was demonstrated that EA protects the liver against I/R induced injury by inhibiting the inflammatory response, which is associated with the vagus.