实验性牙周炎加重大鼠胰岛素抵抗及其对海马区神经元影响的研究

Experimental periodontitis aggravates insulin resistance and its effect on hippocampal neurons in rats

目的初步探讨实验性牙周炎通过调节全身胰岛素抵抗对大鼠海马区神经元的影响。方法将40只6周龄雄性SD大鼠随机分为空白对照(C)、胰岛素抵抗(IR)、单纯牙周炎(P)和胰岛素抵抗复合牙周炎(IR-P)4组。IR、IR-P组高脂饲料喂养12周,P、IR-P组于喂养5周后行双侧上颌第二磨牙结扎。实验13周后处死大鼠,HE染色和体视显微观察牙周组织变化;血糖仪检测空腹血糖水平,酶联免疫吸附试验检测空腹胰岛素浓度,并计算胰岛素抵抗指数(HOMA-IR)及胰岛β细胞功能指数(HOMA-β);免疫组织化学染色检测胰岛β细胞分泌胰岛素情况及肿瘤坏死因子-α(TNF-α)表达水平;尼氏染色观察各组大鼠海马神经元形态和数量。结果与C组相比,P、IR-P组上颌第二磨牙结合上皮向根方退缩,牙槽骨严重吸收(P<0.01),P、IR、IR-P组HOMA-IR评分显著升高(P<0.05),P、IR、IR-P组HOMA-β指数呈下降趋势(P<0.01),IR、IR-P组胰岛素阳性表达平均光密度值明显升高(P<0.01),P、IR、IR-P组胰岛细胞TNF-α均呈强阳性表达,IR-P组神经元结构破坏严重,数量明显减少(P<0.01);与P组相比,IR组HOMA-β指数降低(P<0.01),胰岛素阳性表达平均光密度值升高(P<0.05),IR-P组神经元数量减少(P<0.01);与IR组相比,IR-P组各指标均有统计学意义(P<0.05)。结论在胰岛素抵抗存在情况下,实验性牙周炎下调胰岛β细胞功能并加重大鼠的胰岛素抵抗程度,从而引起大鼠海马区神经元的损伤。

Objective To investigate the effects of experimental periodontitis on neurons in hippocampus of rats by regulating systemic insulin resistance.Methods Forty six-week-old male SD rats were randomly divided into four groups:blank control group(C),insulin resistance group(IR),simple periodontitis group(P)and insulin resistance combined periodontitis group(IR-P).Rats in the IR and IR-P groups were fed with high-fat diet for 12 weeks,and rats in the P and IR-P groups were treated with bilateral ligation of the second maxillary molars after 5 weeks.After 13 weeks of the experiment,rats were sacrificed and the changes of periodontal tissue was observed by HE staining and stereomicroscope.Fasting blood glucose level was observed by blood glucose meter and fasting insulin concentration was detected by enzyme linked immunosorbent assay,which were measured to calculate the HOMA of insulin resistance(HOMA-IR)and the HOMA of Beta-cell function(HOMA-β).Immunohistochemical staining was used to detect insulin secretion of isletβcells and the expression level of tumor necrosis factor-α(TNF-α).The morphology and number of hippocampal neurons were observed by Nissl staining.Results Compared with the C group,the combined epithelium of the second maxillary molar receded to the root side and the alveolar bone was absorbed seriously in the P and IR-P groups.The HOMA-IR scores of P,IR and IR-P groups were higher,the HOMA-βindex of P,IR and IR-P groups were decreased,the average optical density of insulin positive expression in IR and IR-P groups was higher,TNF-αwas highly expressed in the P,IR and IR-P groups,the number of neurons was decreased in the IR-P group.Compared with the P group,the HOMA-βindex of the IR group decreased and the average optical density of insulin positive expression increased as well,the number of neurons decreased in IR-P group.Compared with the IR group,each index of IR-P group had statistical significance.Conclusion In the presence of insulin resistance,experimental periodontitis could decrease the function of isletβcells and increase the degree of insulin resistance,which could cause the damage of neurons in the hippocampus of rats.