八肽胆囊收缩素对游离脂肪酸损伤的胰岛β细胞的保护作用

Protective effect of cholecystokinin-oc-ta-peptide on islet beta cells injured by free fat acid

目的:观察八肽胆囊收缩素对高浓度游离脂肪酸损伤的小鼠胰岛β细胞(NIT-1细胞)的保护作用,并观察同时应用胆囊收缩素受体非特异性拮抗剂丙谷胺对此作用的影响。方法:实验于2004-03/12在河北省人民医院中心实验室进行。将体外培养良好的NIT-1细胞分为对照组、游离脂肪酸组(加入0.25mmol/L软脂酸)、八肽胆囊收缩素组(加入游离脂肪酸同时加入10pmol/L八肽胆囊收缩素)、丙谷胺组(八肽胆囊收缩素组同时加丙谷胺,终浓度32mg/L)。37℃、体积分数为0.05的CO2条件下分别培养48h和72h,放免法测定培养液上清中胰岛素水平;MTT法检测NIT-1细胞增殖情况;流式细胞术方法测定细胞凋亡率;免疫组化法观察Bcl-2的表达。结果:①培养上清中胰岛素水平:游离脂肪酸组48h和72h明显少于对照组(P<0.01);八肽胆囊收缩素组显著高于游离脂肪酸处理组(P<0.01);丙谷胺组与游离脂肪酸组无显著差异。②细胞增殖反应:游离脂肪酸组48h和72h明显低于对照组(P<0.01),八肽胆囊收缩素组则显著高于游离脂肪酸组(P<0.01),丙谷胺组与游离脂肪酸组结果相仿。③细胞凋亡率:游离脂肪酸组48h和72h明显高于对照组(P<0.01),八肽胆囊收缩素组则显著低于游离脂肪酸组(P<0.01),丙谷胺组与游离脂肪酸组结果相仿。④Bcl-2阳性表达水平:游离脂肪酸处理不同时间后其表达明显减少;八肽胆囊收缩素处理后表达增加,丙谷胺组较八肽胆囊收缩素组表达略少。结论:①游离脂肪酸可导致胰岛β细胞明显损伤,表现在胰岛素分泌的减少、细胞增殖能力的降低、细胞凋亡率增加以及bcl-2基因表达减少。②八肽胆囊收缩素对游离脂肪酸损伤的胰岛β细胞具有明显的保护作用。③非特异性胆囊收缩素受体拮抗剂可以在一定程度上逆转八肽胆囊收缩素的保护作用;提示其保护作用可能是通过与胆囊收缩素受体结合实现的。

AIM： To observe the protective effect of eholecystokinin-oc-ta- peptide （CCK-8） on islet beta cells （NIT-1 cells） injured by high concentration free fat acid （FFA）, and observe the influence of gastridine, as a cholecystokinin receptor non-specific antagonist, on this effect. METHODS： The experiment was conducted at the Central laboratory, Heibei Provincial People＇s Hospital from March to December 2004. In vitro cultured NIT-1 cells were divided into control group, FFAs group （added 0.25 mmol/L palmitie acid）, CCK-8 group （added FFAs and 10 pmol/L CCK-8 simultaneously）, proglumide group （added CCK-8 and proglumide with final concentration of 32 mg/L）. The cells were cultured in the condition of 37 ℃ and 5% CO2 for 48 hours and 72 hours, respectively. Insulin secretory volume in supernatant was determined by using radioimmunoassay method. Proliferations of NIT-1 cells were detected by MTT method. Apoptosis rate （AR） of NIT-1 cells were determined by flow cytometry. The expression of Bcl-2 genes was observed by immunohistochemical method. RESULTS： ①Level of insulin in cultured supernatant： It was less in the FFAs group at 48^th hour and 72^th hour than that in the control group （P 〈 0.01）. It was higher significantly in the CCK-8 group than that in the FFAs group （P 〈 0.01）. There was insignificant difference between the gastridine group and FFAs group. ②Reaction of cell proliferation： It was lower obviously in the FFAs group at the 48^th hour and the 72^th hour than that in the control group （P 〈 0.01）. It was higher dramatically in the CCK-8 group than that in the FFAs group （P 〈 0.01）. The results were similar between gastridine group and the FFAs group. ③Apoptosis rate of cell： It was higher markedly in the FFAs group at the 48^th hour and the 72^th hour than that in the control group （P 〈 0.01）. It was lower remarkably in the CCK-8 group than that in the FFAs group （P 〈 0.01）. The results were similar between the gastridine group and the FFAs group. ④Level of the Bcl-2 positive expression： The expression decreased distinctly after the disposal of FFA at different time, but the expression increased after the disposal of CCK-8. The expression in the gastridine group reduced slightly as compared with the CCK-8. CONCLUSION： ①The FFA can damage islet β cell obviously, which displays in reducing insulin secretion, decreasing cell proliferation, increasing apoptosis rate of cells and decreasing the expression of Bcl-2 gene. ②The CCK-8 can create protective role on islet β cells which injured by FFAs. ③Proglumide, as a non-specificity CCK receptor antagonist, can offset the protective effect of CCK-8 on islet cells in some degree. It is indicated that the protective effect of CCK-8 can create through bind-ing with its receptor.