辣木叶对糖尿病大鼠认知功能及海马神经细胞凋亡的影响

Effects of spicy leaves on cognitive function and apoptosis of hippocampal neurons in diabetic rats

目的:探讨辣木叶对链脲佐菌素(STZ)诱导的糖尿病模型大鼠认知功能障碍及海马神经细胞凋亡的影响。方法:选取健康SD雄性大鼠50只,随机选取10只作为对照组,40只大鼠给予腹腔注射25 mg/kg STZ构建糖尿病大鼠模型。40只大鼠随机分为模型组、辣木高、中、低剂量组,分别每日灌胃给药2.0 g/kg、4.0 g/kg、8.0 g/kg辣木叶,对照组和模型组每日灌胃给药等量生理盐水,1次/日,持续给药8周。Morris水迷宫实验评价大鼠学习记忆能力;HE染色及免疫组化染色对大鼠海马神经元切片进行染色,观察各组大鼠海马神经元病理改变的情况及Bax、caspase-3及Bcl-2蛋白表达情况;酶联免疫法(ELISA)检测大鼠海马组织中肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)。结果:与对照组相比,模型组大鼠血糖值明显提高(P<0.01),血胰岛素水平明显降低(P<0.05);与模型组相比,辣木组血糖值显著降低(P<0.05,P<0.01),辣木中、高剂量组血胰岛素水平显著升高(P<0.05,P<0.01)。不同剂量组辣木组间比较,给药后3组大鼠FBG及INS无统计学差异(P>0.05);Morris水迷宫实验的第4-5日,与模型组相比较,辣木各剂量组潜伏期均明显缩短(P<0.05);辣木不同剂量组目标象限停留时间明显延长(P<0.05)。炎症因子变化结果,与模型组相比较,辣木低、中、高剂量组TNF-α、IL-6含量及蛋白表达水平显著降低(P<0.05)。HE染色及免疫组化染色结果显示,与模型组相比较,辣木中剂量组中阳性表达,呈棕黄色,细颗粒状。辣木叶中剂量组(53.21±7.19)能显著减少神经元细胞凋亡的数目(P<0.01);辣木组中剂量组大鼠海马组织中Bax、caspase-3的蛋白表达及Bax/Bcl-2比例显著降低(P<0.05)。结论:辣木叶能改善糖尿病大鼠认知功能障碍其作用机制可能与调节Bax、Bcl-2、caspase-3的蛋白表达,降低炎症因子TNF-α及IL-6含量相关。

Objective:To investigate the effects of Moringa leaves on the cognitive dysfunction and apoptosis of hippocampal neurons in diabetic rats induced by streptozotocin(STZ).Methods:Fifty male SD rats were selected,and 10 rats were randomly selected as the control group.The other 40 rats were treated with STZ at the dose of 25 mg/kg by intraperitoneal injection.The 40 diabetic rats were randomly divided into model group,Moringa oleifera low-dose,medium-dose and high-dose group.The rats in Moringa oleifera groups were treated with Moringa oleifera at the doses of 2.0,4.0 and 8.0 g/kg by gavage,the control group and model group were treated with the same amount of normal saline once a day,for 8 weeks.Morris water maze test was used to evaluate the learning and memory ability of rats.Pathological changes of hippocampal neurons and expressions of Bax,caspase-3 and bcl-2 protein in each group were observed by the sections were stained with HE staining and immunohistochemistry.Enzyme linked immunosorbent assay(ELISA)was used to detect tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in rat.Results:compared with the control group,the blood glucose of the model group was increased significantly(P<0.01),and the blood insulin level was decreased significantly(P<0.05);compared with the model group,the blood glucose values of Moringa oleifera groups were decreased significantly(P<0.05,P<0.01),and the blood insulin levels of middle and high dose Moringa oleifera group were increased significantly(P<0.05,P<0.01).There was no significant difference in FBG and INS among the three groups(P>0.05).In Morris water maze test,compared with the model group,the latency of Moringa oleifera groups was significantly shorter(P<0.05);the residence time in target quadrant of Moringa oleifera groups with different doses was significantly prolonged(P<0.05).Compared with the model group,the contents of TNF-α,IL-6 and protein expression in low,medium and high dose groups of Moringa oleifera were decreased significantly(P<0.05).HE staining and immunohistochemical staining results showed that Moringa oleifera medium dose group was positive,brown yellow,fine granular,compared with the model group.The number of neuronal apoptosis was significantly reduced in the middle dose group(53.21±7.19,P<0.01);the protein expressions of Bax,caspase-3 and the ratio of Bax/Bcl-2 in hippocampus were significantly decreased in the middle dose group(P<0.05).Conclusion:The mechanisms of Moringa leaves on the cognitive dysfunction and apoptosis of hippocampal neurons may be related to regulating the protein expressions of Bax,Bcl-2 and Caspase-3,reducing the contents of inflammatory factors TNF-αand IL-6.