Mesenteric lymph reperfusion exacerbates brain injury in superior mesenteric artery occlusion shock rats

AIM: To observe the effect of mesenteric lymph reperfusion (MLR) on the brain morphology and neurotransmitter in rats with superior mesenteric artery occlusion (SMAO) shock, and to explore the mechanism of oxygen free radicals, nitric oxide (NO), polymorphonuclear neutrophils (PMN), membrane ATPase function and energy metabolism. METHODS: Twenty-four male Wistar rats were randomly divided into 4 groups: in sham group, the rats were given only anesthetization and operation; in MLR group, the rats were performed 1 h occlusion of mesenteric lymphatics (ML) followed by 2 h of reperfusion; in SMAO group, the rats were performed 1 h occlusion of superior mesenteric artery (SMA) followed by 2 h of reperfusion; in MLR+SMAO group, the rats were performed 1 h occlusion of SMA and ML followed by 2 h of reperfusion. After 2 h of reperfusion, the brain tissue was taken for preparing microscopic sections to observe the morphological change. At the same time, the brain tissue was homogenized for determining the choline acetyltransferase (ChAT), acetylcholine esterase (AChE), dopamine (DA), norepinephrine (NE), lactic acid (LA), malondialdehyde (MDA), superoxide dismutase (SOD), NO, nitric oxide synthase (NOS), myeloperoxidase (MPO), cell membrane ATPase and ATP. RESULTS: Morphological observation showed that the architecture of the brain was close to normal in sham and MLR groups. Necrosis, degeneration and occasional swelling were found in neuronal cells in SMAO group, and in MLR + SMAO group the injury of the neurons was more serious than that in SMAO group. The contents of MDA, NO and LA, the activities of AChE, NOS and MPO in brain homogenate in SMAO and MLR+SMAO groups were increased, the ChAT activity and DA, NE contents were reduced significantly than those in MLR and sham groups, respectively. The contents of MDA and NO, the activities of AChE, NOS and MPO in MLR+SMAO group were higher than those in SMAO group. The activities of Na+-K+-ATPase and SOD in brain homogenate in SMAO group were lower than those in sham and MLR groups, the Mg2+-ATPase activity and ATP content were lower than those in MLR group. The activities of SOD, Na+-K+-ATPase, Ca2+-ATPase, Mg2+-ATPase and Ca2+-Mg2+-ATPase in brain homogenate in MLR+SMAO group were lower than those in sham and MLR groups, and the DA, Ca2+-ATPase, Mg2+-ATPase, Ca2+-Mg2+-ATPase and ATP were also lower than those in SMAO group. CONCLUSION: MLR exacerbates the brain injury, reduces the DA level and increases the AChE activity in SMAO shock rats, indicating that MLR enhances the brain tissue free radical injury, NO synthesis and releases, PMN detention, and decreases the activity of cell membrane ATPase, also induces the energy metabolism dysfunction.