Effect of acupuncture on hippocampal inflammation in rats with intrauterine distress induced hypoxic-ischemic brain injury

Abstract

To observe the effects of acupuncture on the behavior, serum inflammatory cytokines, hippocampal Nod-like receptor protein 3(NLRP3) inflammasome-related proteins and microglia activation in rats with intrauterine distress induced ischemia-hypoxic brain injury (HIBD), so as to explore the mechanism of acupuncture underlying treatment of HIBD by regulating hippocampal inflammation. The HIBD model was established by clipping bilateral uterine arteries for 10 min and delaying caesarean delivery. HIBD rats were randomly divided into model group and acupuncture group according to body weight and litter factors, with 12 rats in each group. Twelve rats delivered normally were regarded as the normal group. Acupuncture was applied to bilateral "Benshen"(GB13) for 10 min, once a day for 14 consecutive days. H.E. staining was used to observe the pathological changes of hippocampus. The three chamber sociability test was used to determine the rat's social ability. The serum IL-1β and IL-18 levels, the hippocampal expressions of NLRP3, apoptosis associated speck like protein containing CARD(ASC) and cysteinyl aspartate specific proteinase-1(Caspase-1), andionized calcium bindingadaptor molecule-1(IBA-1) were detected by ELISA，Western blot and Immunofluorescence, separately. Compared with the normal group, The hippocampal neurons in the model group are arranged loosely, and the cells are solidified and shrunk and the whole cells are deeply stained. The time of exploring the stranger rat in the model group was significantly reduced (P<0.01). The contents of IL-1β and IL-18, the expressions of NLRP3, ASC, Caspase-1 and IBA-1 of the model group were higher than those of the normal group (P<0.01, P<0.05, P<0.001). Following acupuncture intervention, the cell structure of hippocampal neurons was improved, and there were fewer cases of cell solidification, atrophy, and deep staining. In comparison with the model group, the time of exploring stranger rat in the acupuncture group was significantly increased (P<0.01). The contents of IL-1β and IL-18, the expressions of NLRP3, ASC and Caspase-1, and IBA-1 of the acupuncture group were significantly down-regulated than those of the model group (P<0.01, P<0.05). Acupuncture can effectively improve the social behavior deficits of HIBD rats，which may be related to inhibition of the expression of inflammatory response proteins NLRP3, ASC and Caspase-1 in the hippocampus, decrease the activation of microglia in the hippocampus, and reduce serum IL-1β and IL-18, thereby alleviating inflammation.