科罗索酸对妊娠期糖尿病大鼠胰岛β细胞保护作用研究

Study on the protective effect of corosolic acid on pancreatic beta cells of rats with gestational diabetes mellitus

目的:观察口服给予科罗索酸对妊娠期糖尿病大鼠模型血糖及糖耐量的影响,同时观察其对妊娠期糖尿病大鼠胰岛β细胞保护作用。方法:雌性SD大鼠随机分为4组,正常对照组和孕鼠对照组给予标准饲料,妊娠期糖尿病模型组和科罗索酸治疗组给予高脂饲料,在喂养至第8周时,科罗索酸治疗组大鼠给予20 mg/kg体重剂量的科罗索酸,每天1次持续至实验结束。在第12周时除对照组外,其余3组与雄性SD大鼠配对,出现阴栓记为妊娠第0天。高脂饲料喂养期间每周测定空腹血糖,在妊娠第18天测定各组大鼠口服葡萄糖耐量。实验结束后处死大鼠,取胰腺固定于4%多聚甲醛中,石蜡包埋切片,针对胰岛素抗体做免疫组织化学分析,利用TUNEL试剂盒检测胰岛β细胞凋亡。结果:①给予高脂饲料喂养的大鼠在孕期发生高胰岛素血症,血糖显著上升,糖耐量受损明显(P值均<0.05)。②而提前口服给予科罗索酸组孕鼠高胰岛素血症改善,血糖得到良好控制,糖耐量也恢复接近正常水平(P值均<0.05)。③免疫组织化学的胰岛素染色结果显示,糖尿病孕鼠胰岛中胰岛β细胞受损比例增加,而科罗索酸给药组则显著恢复。④TUNEL凋亡染色结果显示,科罗索酸显著减少了妊娠期糖尿病大鼠胰岛β细胞凋亡。结论:妊娠期糖尿病可能由多种因素诱发形成,其中胰岛β细胞受损可能是患者最终诱发2型糖尿病的重要原因。科罗索酸能够有效保护胰岛β细胞,改善妊娠期糖尿病大鼠血糖及糖耐量,为妊娠期糖尿病的防治提供帮助。

Objective： To observe the effect of oral administration of corosolic acid on blood glucose level and glucose tolerance in rats with gestational diabetes mellitus（ GDM） and its protective effect on pancreatic beta cells. Methods： Female SD rats were divided into four groups randomly. The rats in normal control group and pregnant control group were given standard diet,while the rats in GDM model group and corosolic acid treatment group were given high- fat- diet. On the eighth week after feeding,the rats in corosolic acid treatment group were given corosolic acid（ 20 mg /kg）,once a day until the end of experiment. On the twelfth week,the female rats were mated with normal male SD rats except the rats in normal control group. The day finding vaginal plug was designed as the tenth day. During the experiment,the fasting blood glucose was measured every week. Oral glucose tolerance test was performed on the eighteenth day of gestation. After experiment,the rats were executed and the pancreatic tissue was obtained for fixation in 4% paraformaldehyde to make paraffin sections. Immunohistochemistry of insulin antibody was performed. TUNEL analysis was used to detect apoptosis of pancreatic beta cells. Results： There was a significant increase of serum insulin and blood glucose level during gestation in high- fat- diet- treated rats（ P〈0. 05）,and the impaired glucose tolerance was also observed（ P〈0. 05）. However,the corosolic acid- treated pregnant rats had a better glucose profile（ P〈0.05）. The results of immunohistochemistry showed that the decreasing in insulin-positive cells of pancreatic islets of gestational diabetic rats was also reversed by corosolic acid treatment. The apoptotic pancreatic beta cells were also significantly reduced by corosolic acid.Conclusion： Multiple mechanisms may be involved in GDM,in which the dysfunction of pancreatic beta cells is one of the most important reasons inducing type 2 diabetes. Corosolic acid can protect pancreatic beta cells from apoptosis and improve glucose profile in gestational diabetic rats,which may provide benefits for prevention and treatment of GDM.