Pretreatment Protects Against Liver Ischemia/reperfusion Injury In Rats Through Activating The Cholinergic Anti-inflammatory Pathway

BackgroundLiver ischemia/reperfusion injury (HIRI) is an important clinical complication of hemorrhagic shock, hepatic trauma, resection surgery, transplantation. The pathophysiology is complex. There are many factors participated the injury and they are restricted or promoted with each other. There injury shown biphasic phases in early:The 1-6h followed the reperfusion beginning is the acute injury phase which shown as activated massive Kupffer cell and released of the pro-inflammatory cytokines and generated of reactive oxygen species (ROS). The second phase followed 6h is called sub-acute, which characterized as neutrophil infiltration and product the inflammatory mediators and the Kupffer cell function was inhibited by diminishing cytokine production and liver I/R injury. There were some studies demonstrated that the excessive inflammation is one of the important courses which promotes HIRI. So how to control the "excessive" become a key point to protected the injured liver. But the effective therapy to the inflammation is still pursued. In the past years, the studies were more focused on humoral factors and autocrine or paracrine of cytokines. In recent, the nerves and its production would be more attention. The cholinergic anti-inflammatory pathway (CAIP) was named in New York in 2000. It was found that direct electro-stimulated vagus could effectively mitigate the inflammation caused by LPS in rodents. And followed this theory, some studies shown that electroacupuncture (EA) has the similar effects as the pathway but didn't focus on the protection of organ function especially liver. Acupuncture had thousands years history and effective therapy of diseases. But its mechanism couldn't be explained by the modern biology theory. So the current study used IL-4 (Hegu) to explore the EA protected function of liver and if this achievement was though activated CAIP.Methods1. The SD-rats were divided into sham and HIRI. Both two groups were further divided into four sub groups; control (A), non-point acupuncture (B), DMPPI (C) and EA of Hegu (D).2. The portal circulation to the median and left lateral lobes of the rat liver was carefully dissected, and a 3cm bending atraumatic vascular clip was placed on the vessels, interrupting the portal venous and hepatic arterial blood supply to these lobes and that called 70% HIRI. The rats got MH or subphrenic vagotomy were vagus blocking.3. The serum ALT was tested by auto-bioassay; H&E staining was shown the liver tissue injury; The liver tissue MPO and serum cytokines such as TNF-a, IL-1b, IL-6 and IL-10 were tested by ELISA; The cytokines mRNA were tested by real-time PCR.Results1. The serum ALT of sham had no obvious different in the groups that illustrated the EA, NPA or DMPPI would not contribute the HIRI.2. The serum ALT and liver tissue MPO of D group were lower than A or B groups that illustrated the EA could effectively inhibit the HIRI or neutrophil infiltration. The H & E staining further proved the results.3. The serum pro-cytokines TNF-a,IL-1b or IL-6 of D group were lower than A or B groups but no different in liver tissue mRNA that illustrated the effect of EA on inflammatory cytokines was only at serum protein level.4. The serum anti-inflammatory cytokines and its mRNA both were no different in A, B or D groups that illustrated the EA had no effect on ant-cytokines.5. The results of D group were no different as C group that illustrated the EA has similar function about DMPPI. In the vagus blocked, EA has no protection about the HIRI that illustrated the mechanism maybe is CAIP.ConclusionsThe current study's findings indicate that the EA could effectively protect the HIRI through reduce the over-expressed inflammatory cytokines such as TNF-a, IL-1b or IL-6 but not impact the anti-inflammatory IL-10. And that consequent is proved through activating CAIP such as direct electro-stimulated vagus.