Abstract: Objective To investigate the effect of melatonin on the proliferation, function and p38 MAPK protein expression of pancreatic β cells. MethodIns-1 cells were used as the research object. Six treatment groups and one control group were divided according to the concentration of melatonin to observe the dose-effect relationship of melatonin on the proliferation and function of INS-1 cells. The proliferation rate was detected by CCK-8 method, and the glucose-stimulated insulin secretion (GSIS) function was detected by ELISA. Four groups were divided to observe the effect of melatonin on the expression of p38 MAPK protein, and the expression levels of p38 MAPK and p-p38 MAPK protein were detected by Western blot. Results Compared with the control group, the proliferation rate of each treatment group decreased significantly, and the cell proliferation rate first increased and then decreased with the increase of melatonin concentration, and the proliferation rate of the 10 nmol/L melatonin group was the highest. Compared with the control group, the insulin concentrations of the 1 nmol/L, 5 nmol/L, 25 nmol/L, 50 nmol/L and 100 nmol/L melatonin groups were significantly decreased, and the differences were statistically significant (all P<0.05). The increase of melatonin concentration first increased and then decreased, with the highest in the 10 nmol/L melatonin group. Compared with the control group, both the melatonin group and the SB203580 group could significantly reduce the expression levels of p38 MAPK and p-p38 MAPK proteins (both P<0.05); compared with the melatonin group or the SB203580 group, the expression levels of p38 MAPK and p-p38 MAPK proteins in the combined group were significantly decreased (both P<0.05). Conclusion Melatonin has an inverted U-shaped damage on islet β cells, and 10 nmol/L melatonin has the least damage; melatonin inhibits the p38 MAPK signaling pathway of islet β cells.

Key words: melatonin, diabetes, insulin, INS-1 cells, p38 MAPK, proliferation

摘要： 目的 探讨褪黑素对胰岛β细胞增殖、功能和p38 MAPK蛋白表达的影响。方法 采用小鼠胰岛β细胞株INS-1细胞作为研究对象。按褪黑素加药浓度分6个处理组和1个对照组,观察褪黑素对INS-1细胞的增殖和功能影响的剂量效应关系,CCK-8法检测细胞的增殖率,ELISA法检测细胞的葡萄糖刺激胰岛素分泌（GSIS）功能。分4组以观察褪黑素对p38 MAPK蛋白表达的影响,Western blot法检测p38 MAPK和p-p38 MAPK蛋白表达水平。结果 与对照组相比较,各褪黑素组增殖率均显著下降,且细胞增殖率随褪黑素浓度的增加先升后降,以10 nmol/L褪黑素处理组的增殖率最高。GSIS实验结果显示,与对照组相比较,1 nmol/L、5 nmol/L、25 nmol/L、50 nmol/L和100 nmol/L褪黑素组的胰岛素浓度均显著下降,差异均有统计学意义（均P<0.05）,且GSIS功能随褪黑素浓度的增加先升后降,以10 nmol/L褪黑素组最高。Western blot实验结果显示,与对照组相比,褪黑素组和SB203580组均能显著降低p38 MAPK和p-p38 MAPK蛋白的表达水平（均P<0.05）;与褪黑素组或SB203580组相比,褪黑素联合SB203580处理组p38 MAPK和p-p38 MAPK蛋白的表达水平均显著降低（均P<0.05）。结论 褪黑素对胰岛β细胞呈现倒U型损害作用,10 nmol/L褪黑素损害最小;褪黑素对胰岛β细胞p38 MAPK信号通路产生抑制作用。

关键词: 褪黑素, 糖尿病, 胰岛素, INS-1细胞, p38 MAPK, 增殖