甜菊苷甙对高脂饮食大鼠胰岛β细胞功能和脂肪代谢的影响

Effects of rebaudioside A on the β cell function and lipid metabolism in rats fed high-fat diets

目的 探讨甜菊苷甙(RA)对高脂饮食大鼠B细胞功能和脂肪代谢的影响.方法 将10周龄雄性SD大鼠30只按随机数字表法分为健康对照组、高脂饲养组和高脂饲养干预组(腹腔注射RA 30 mg·kg-1·d-1),每组10只.所有受试大鼠8周后腹腔注射葡萄糖耐最试验.测定肝脏、肌肉中甘油三酯的含最,使用逆转录-实时聚合酶链反应吸附试验分析肝脏和肌肉巾脂代谢调控基因mRNA的表达.结果 (1)腹腔注射匍萄糖耐量试验30 min时胰岛素水平在健康对照组、高脂饲养组和高脂饲养干预组分别为(16.0±6.1)、(5.4±0.8)和(23.9±7.1)μg/L,三组间比较有统计学意义(F=3.77,P均<0.05);30 min时高脂饲养干预组血糖明显高于健康对照组、高脂饲养组(F=3.83,P均<0.05).(2)高脂饲养组和高脂饲养干预组较健康对照组肌肉(F=4.39,P<0.05)和肝脏甘油三酯(F=5.97,P<0.01)含量显著增加,其中高脂饲养干预组肌肉含量最高.(3)高脂饲养组和高脂饲养干预组肌肉中乙酰辅酶A羧化酶-2(ACC-2)的表达分别是健康对照组的1.74倍和19.97倍(F=13.48,P<0.01);肌肉肉毒碱脂酰转移酶-1(M-CPT-1)表达仅在高脂饲养组显著增加.结论 甜菊苷甙能保护脂毒性对葡萄糖耐量试验早时相的胰岛素分泌损害,但能升高血糖水平.推测可能与甜菊苷甙改变肌肉脂肪酸代谢,使肌肉的脂肪沉积增加有关.

Objective To study the effect of high-fat diet and rebaudioside (RA) intervention on the function of β cell and lipid metabolism of SD rats. Methods Ten-week-old male SD rats were randomly divided into 3 groups, i. e. , the normal group (NC, n = 10), the high-fat diet group (HF, n = 10), and the high-fat diet plus RA intervention group (HF + R, n = 10). Rats in HF + R group was administered RA saline. Intraperitoneal glucose tolerance test (IPGTT) were carried out after eight weeks of feeding. Triglycerides (TG) content in liver and in muscle was calculated. The mRNA expression of genes involved in fatty acid metabolism was measured by using reverse transcription and real-time PCR. Results (1) At the 30 min of the IPGTT, the insulin levels in NC, HF, HF + R group were (16.0±6.1) ,(5.4±0.8) and (23.9±7.1) μg/L, respectively (F = 3.77, all P < 0.05) ; the blood glucose at the 30 rain in rats of HF + R increased significantly as compared with NC group and HF group (F = 3.83, P < 0.05). (2) TG content of muscle and liver in HF and HF + R group increased significantly than NC group (F =4.39,P < 0.05 in muscle, F = 5.97, P < 0.01 in liver). (3) The expression of acetyl coenzyme A carboxylase -2 (ACC-2) in rat muscle of HF group and HF + R group was 1.74 fold and 19.97 fold higher than that in NC group, respectively (F = 13.48, P < 0.01) ; Compared with the NC group, the muscle carnitine acyltransferase 1 (M-CPT-1) was increased only in HF group . Conclusion RA preserved early phase insulin secretion in rats feeding with high-fat diet, however, the blood glucose level was higher. The increased TG contents and the change of gene expression in muscle may account for the increased glucose level.