Effects of lymphatic drainage and omega-3 polyunsaturated fatty acids on intestinal ischemia-reperfusion injury in rats

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To investigate the effects of lymphatic drainage and omega-3 polyunsaturated fatty acid (omega-3PUFA) on high mobility group box 1 (HMGB1), inflammatory cytokines and endotoxin in rats with intestinal ischemia-reperfusion (I/R) injury. A total of 72 SD rats were randomly divided into drainage-alone group, I/R group, ischemia-reperfusion plus drainage (I/R + D) group (n = 8 each) and 3 groups with 16 rats undergoing gastrostomy in each group: normal diet (N) group, enteral nutrition (EN) group and enteral nutrition & omega-3PUFA (PUFA) group. And they were further divided into 2 subgroups (n = 8). The rats in I/R and I/R + D groups were subjected to a 60-min ischemia follow by 120-min reperfusion injury of superior mesenteric artery. When the rats suffered I/R injury, intestinal lymph was drained for 180 min in the I/R + D group. The rats in the drainage-alone group received 180-min lymph drainage without I/R injury. After 5 days with different nutrition regimes, the models were established similarly. The rats in the I/R + D sub-groups were treated with intestinal lymph drainage for 180 min. The serum and lymph samples were collected post-operatively. Endotoxin was detected by a Limulus kit. The inflammatory cytokines and high mobility group box 1 (HMGB1) were analyzed by enzyme-linked immunosorbent assay (ELISA). Endotoxin, inflammatory cytokines and lymphatic HMGB1 of lymphatic in the I/R + D group were higher than those in the drainage-alone group [all P < 0.05, IL-6: (30 +/- 8) pg/ml vs (20 +/- 6) pg/ml, endotoxin: (0.029 +/- 0.011) U/ml vs (0.008 +/- 0.005) U/ml]. The serum levels of endotoxin and inflammatory cytokines in the I/R + D group were lower than those in the I/R group (P < 0.05). The lymphatic levels of TNF-alpha (tumor necrosis factor-alpha) and HMGB1 in the N and EN groups were higher than those in the PUFA group[ TNF-alpha: (46 +/- 17) pg/ml, (54 +/- 16) pg/ml vs (28 +/- 9) pg/ml, HMGB1: (4.8 +/- 1.6) ng/ml, (5.3 +/- 1.8) ng/ml, (3.0 +/- 1.0) ng/ml, all P < 0.05)]. The serum levels of endotoxin, inflammatory cytokines and HMGB1 in the PUFA (I/R) group were lower than those in the N (I/R) group (P < 0.05). The levels of TNF-alpha and HMGB1 were lower in the PUFA (I/R + D) group than those in the N (I/R + D) group (both P < 0.05). Lymphatic drainage may reduce the levels of endotoxin, inflammatory cytokines and HMGB1 so as to alleviate the intestinal I/R injury. The intervention of omega-3PUFA has some protective effect through relieving inflammation.