Protective Effects Of Two Post-conditioning Methods In Small Intestinal Damage Caused By Rat Limb Ischemia-reperfusion

Objective:The purpose of this study was to investigate the protective effects of ischemia post-conditioning and Penehyelidine hydrochloride post-conditioning on damage to the barrier function of the small intestine caused by limb ischemia-reperfusion (LIR) injury.Method:One hundred forty-four male Wistar rats were randomly divided into 4 groups (n=36):a sham operation group (group S), a lower limb ischemia-reperfusion group (group LIR), a post-conditioning group (group PC) and a Penehyelidine hydrochloride post-conditioning (group PHC). Each group was divided into subgroups (n=6) according to reperfusion time:immediate (0 hours; T1),1 hour (T2), 3 hours (T3),6 hours (T4),12 hours (T5), and 24 hours (T6). In the PC group,3 cycles of reperfusion followed by ischemia (each lasting 30 seconds) were applied immediately. In group PHC,0.15 mg/kg of penehyclidine hydrochloride was injected into the tail vein immediately after 3 h of bilateral hind-limb ischemia. At all reperfusion times (T1-T6), diamine oxidase (DAO), superoxide dismutase (SOD), and myeloperoxidase (MPO) activity, malondialdehyde (MDA) intestinal tissue concentrations, plasma endotoxin concentrations, and serum DAO, TNF-α, and interleukin -10 (IL-10) concentrations were measured in sacrificed rats. Chiu's pathology scores for small intestinal mucosa were determined under a light microscope.Result:1. Damage of small intestinal mucosa:The small intestinal tissue of groups LIR and PC showed varying degrees of pathological changes. According to Chiu's scores, damage of small intestinal mucosa in group PC was less than that of group LIR.2. In group PC and PHC, tissue DAO at T2 to T6 were higher than that in group LIR (P<0.05); however, serum DAO and endotoxin concentrations at T2 to T6 decreased significantly (P<0.05).3. In group PC and PHC, SOD concentrations at T2 to T6, and IL-10 concentrations at T2 to T5 were higher than those in group LIR (P<0.05); however, tissue MPO and MDA concentrations at T2 to T6, as well as TNF-a at T2 and T4 decreased significantly (P<0.05).4. In group LIR, PC and PHC, the tissue MDA concentration, SOD, MPO, and DAO activities, serum DAO and endotoxin reached their peak at T4 (P<0.05); TNF-a reached its peak at T2 (P<0.05). Thereafter, TNF-a gradually decreased, and even decreased at T5 and T6 in the group S (P≥0.05); IL-10 at T3 exhibited the highest concentration (P<0.05), even at T4 and T5, the serum IL-10 also maintained a relatively high concentration.5. Compared with PC group, DAO at T6, SOD activity at T4 to T6, MPO activity at T4 to T6, and MDA concentration at T2 and T5 of small intestinal tissue, as well as DAO at T2, TNF-a at T2 to T3 and IL-10 at T3 of serum in PHC group, had significant difference (P<0.0).Conclusion:These results show that ischemia post-conditioning and Penehyelidine hydrochloride post-conditioning attenuated the permeability of the small intestines after LIR. Protective effect of penehyclidine hydrochloride on small intestinal mucosa under the limbs ischemia-reperfusion was better than that of ischemic postconditioning. The protection mechanism of post-conditioning may be related to inhibition of oxygen free radicals and inflammatory cytokines that cause organ damage.