摘要目的 观察严重烫伤早期大鼠胰岛β细胞胰岛素分泌功能的变化,探讨艾塞那肽4对严重烫伤大鼠胰岛β细胞分泌功能的影响. 方法 将36只Wistar大鼠按随机数字表法分为单纯假伤组、假伤+艾塞那肽4组、单纯烫伤组、烫伤+艾塞那肽4组,每组9只.单纯烫伤组、烫伤+艾塞那肽4组大鼠在94℃热水中浸浴背部12 s、腹部6 s,造成50％ TBSA Ⅲ度烫伤;单纯假伤组、假伤+艾塞那肽4组大鼠在37℃温水中浸浴背腹部模拟致伤.假伤+艾塞那肽4组、烫伤+艾塞那肽4组大鼠伤后皮下注射艾塞那肽4(4μg/kg),2次/d;单纯假伤组、单纯烫伤组大鼠伤后皮下注射等体积灭菌注射用水.于伤后72 h,进行如下检测.每组取8只大鼠剪尾法检测空腹血糖水平;ELISA法检测血浆胰高血糖素样肽1(GLP-1)水平、血清胰岛素水平,并计算胰岛素抵抗指数(HOMA-IR).每组取6只大鼠分离的胰岛,分别采用含2.8 mmol/L葡萄糖和16.7 mmol/L葡萄糖的RPMI 1640培养基培养,用ELISA法检测上清液中胰岛素含量,并计算胰岛素分泌指数(SI),每组样本数为6.每组取3只大鼠分离的胰岛,采用透射电镜观察胰岛β细胞超微结构,并计算每10微米细胞膜上附着颗粒的数量及胰岛素空泡占胰岛素颗粒总数的比例,每组样本数为3.对数据行单因素方差分析、LSD检验. 结果 (1)与单纯烫伤组比较,单纯假伤组、假伤+艾塞那肽4组、烫伤+艾塞那肽4组大鼠空腹血糖水平均明显降低(P ＜0.05或P＜0.01).(2)与单纯假伤组比较,假伤+艾塞那肽4组大鼠血浆GLP-1水平明显升高(P＜0.05),血清胰岛素水平、HOMA-IR差异不明显(P值均大于0.05);单纯烫伤组和烫伤+艾塞那肽4组大鼠血浆GLP-1水平均降低(P值均小于0.01),血清胰岛素水平、HOMA-IR均升高(P值均小于0.01).与假伤+艾塞那肽4组比较,单纯烫伤组和烫伤+艾塞那肽4组大鼠血浆GLP-1水平均明显降低(P值均小于0.01),血清胰岛素水平、HOMA-IR均升高(P值均小于0.01).与单纯烫伤组比较,烫伤+艾塞那肽4组大鼠血浆GLP-1水平、血清胰岛素水平均升高(P值均小于0.01),HOMA-IR降低(P＜0.05).(3)采用2.8 mmol/L葡萄糖刺激时,4组大鼠的胰岛素分泌量组间总体比较差异无统计学意义(P＞0.05).采用16.7 mmol/L葡萄糖刺激时,与单纯假伤组比较,假伤+艾塞那肽4组和烫伤+艾塞那肽4组大鼠胰岛素分泌量增加(P＜0.05或P＜0.01),单纯烫伤组大鼠胰岛素分泌量减少(P＜0.05);与假伤+艾塞那肽4组比较,单纯烫伤组大鼠胰岛素分泌量减少(P＜0.0l);与单纯烫伤组比较,烫伤+艾塞那肽4组大鼠胰岛素分泌量明显增加(P＜0.01).与单纯假伤组(2.25±0.20)比较,烫伤+艾塞那肽4组大鼠胰岛素SI(2.68±0.24)升高(P＜0.05);与假伤+艾塞那肽4组(2.47±0.18)比较,单纯烫伤组大鼠胰岛素SI(2.11±0.28)降低(P＜0.05);与单纯烫伤组比较,烫伤+艾塞那肽4组大鼠胰岛素SI明显升高(P＜0.01).(4)与单纯假伤组比较,烫伤+艾塞那肽4组大鼠胰岛β细胞内每10微米细胞膜附着颗粒的数量明显增多(P＜0.05);单纯烫伤组大鼠胰岛β细胞内胰岛素空泡比例增加(P＜0.01).与假伤+艾塞那肽4组比较,单纯烫伤组大鼠胰岛β细胞内每10微米细胞膜附着颗粒的数量明显减少(P＜0.01),胰岛素空泡比例明显增加(P＜0.05).与单纯烫伤组比较,烫伤+艾塞那肽4组大鼠胰岛β细胞内每10微米细胞膜附着颗粒的数量明显增多(P＜0.0i),胰岛素空泡比例明显减少(P＜0.05). 结论 严重烫伤早期大鼠体内GLP-1水平下降,胰岛β细胞胰岛素分泌功能受损,补充长效GLP-1类似物艾塞那肽4能显著改善烫伤大鼠胰岛β细胞的胰岛素分泌功能.

abstractsObjective To observc the secretion function changes of islet beta cells isolated from rats in the early stage of severe scald,and to explore the influence of them.Methods Thirty-six Wistar rats were divided into sham injury (SI) group,sham injury + exendin-4 (SIE) group,scald (S) group,and scald + exendin-4 (SE) group according to the random number table,with 9 rats in each group.Rats in groups S and SE were inflicted with 50％ total body surface area full-thickness scald by a 12-s immersion of back and a 6-s immersion of abdomen in 94 ℃ hot water.Rats in groups SI and SIE were sham injured through immersion of back and abdomen in 37 ℃ warm water.Rats in groups S and SE were subcutaneously injected with exendin-4 (4 μg/kg) twice a day post injury,while rats in groups SI and SIE were subcutaneously injected with sterile water in the same volume.At post injury hour (PIH) 72,the following detections were performed.Eight rats of each group were respectively selected to measure level of fasting blood glucose with cutting-tail method,and to detect plasma level of glucagon-like peptide 1 (GLP-1) and serum level of insulin by enzyme-linked immunosorbent assay (ELISA).The insulin resistant index (HOMA-IR) was calculated.Six rats of each group were respectively selected for islet isolation.The isolated rat islets were stimulated with RPMI 1640 medium containing 2.8 or 16.7 mmol/L glucose,respectively.Insulin content in supernatant was detected by ELISA,and insulin secretion index was calculated with 6 samples in each group.The isolated islets from 3 rats of each group were selected for the observation of the super-structure of islet beta cells under transmission electron microscope.The number of docked granules in per 10 μm membrane of islet beta cells and the ratio of insulin vesicles to the total insulin granules were calculated with 3 samples in each group.Data were processed with one-way analysis of variance and LSD test.Results (1) Compared with that in group S,levels of fasting blood glucose of rats in group SI,SIE,and SE were significantly decreased (P ＜ 0.05 or P ＜ 0.01).(2) Compared with those in group SI,plasma level of GLP-1 of rats in group SIE was significantly increased (P ＜ 0.05),while serum level of insulin and HOMA-IR of rats did not change obviously (with P values above 0.05).Plasma levels of GLP-1 of rats in groups S and SE were significantly decreased (with P values below 0.01),while serum levels of insulin and HOMA-IR were obviously increased (with P values below 0.01).Compared with those in group SIE,plasma levels of GLP-1 of rats in groups S and SE were significantly decreased (with P values below 0.01),while serum levels of insufin and HOMA-IR were significantly increased (with P values below 0.01).Compared with those in group S,plasma level of GLP-1 and serum level of insulin of rats in group SE were significantly increased (with P values below 0.01),while HOMA-IR was significantly decreased (P ＜ 0.05).(3) There was no statistically significant difference in the insulin secretion content of rats in the 4 groups when stimulated with 2.8 mmol/L glucose (P ＞ 0.05).Under stimulation of 16.7 mmol/L glucose,compared with that in group SI,the insulin secretion content of rats in groups SIE and SE were significantly increased (P ＜ 0.05 or P ＜ 0.01),while in group S it was significantly decreased (P ＜ 0.05).Compared with that in group SE,the insulin secretion content of rats in group S was significantly decreased (P ＜ 0.01).Compared with that in group S,the insulin secretion content of rats in group SE was significantly increased (P ＜ 0.01).Compared with that in group SI (2.25 ± 0.20),the insulin secretion index of rats in group SE (2.68 ± 0.24) was significantly increased (P ＜ 0.05).Compared with that in group SIE (2.47 ± 0.18),the insulin secretion index of rats in group S (2.11 ± 0.28) was significantly decreased (P ＜ 0.05).Compared with that in group S,the insulin secretion index of rats in group SE was significantly increased (P ＜ 0.01).(4) Compared with those in group SI,the number of docked granules per 10 μm membrane of islet beta cells in group SE was significantly increased (P ＜ 0.05),while the ratio of insulin vesicles of rat islet beta cells in group S was significantly increased (P ＜0.01).Compared with those in group SE,the number of docked granules per 10 μm membrane of islet beta cells in group S was significantly decreased (P ＜0.01),while the ratio of insulin vesicles of rat islet beta cells was significantly increased (P ＜ 0.05).Compared with those in group S,the number of docked granules per 10 μm menbrane of islet beta cells in group SE was significantly increased (P ＜ 0.01),while the ratio of insulin vesicles of rat islet beta cells was significantly decreased (P ＜ 0.05).Conclusions In the early stage of severe scald in rats,level of GLP-1 is decreased and the insulin secretion function of islet beta cells is injured.Long-lasting GLP-1 analogous exendin-4 can improve the secretion function of isolated islet beta cells from severely scalded rats.