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目的探讨增龄对高脂喂养大鼠胰岛素抵抗(IR)和骨骼肌内脂肪影响的可能机制。方法将雄性Wistar4～5月龄大鼠16只和22～24月龄大鼠16只分别随机分为青年对照组和老年对照组,青年高脂组和老年高脂组(高脂饲料喂养),每组8只。8周后,行葡萄糖耐量试验,测定0、30、60和120min的血糖和葡萄糖曲线下面积(AUC);采用正葡萄糖-高胰岛素钳夹试验的葡萄糖输注率(GIR)评价IR。结果与老年对照组和青年对照组比较,老年高脂组和青年高脂组GIR降低,骨骼肌TG及长链酯酰辅酶A(LCACoA)明显升高,差异有统计学意义(P<0.05,P<0.01);与老年对照组比较,老年高脂组大鼠各时间点血糖及AUC比较,差异均有统计学意义(P<0.05,P<0.01)。GIR与胰岛素、骨骼肌TG及LCACoA呈负相关。结论老年和高脂喂养大鼠骨骼肌TG和LCACoA含量增加,可能是老年容易发生IR的原因之一。
Objective To explore the possible mechanism of aging on insulin resistance (IR) and skeletal muscle fat in high fat diet rats. Methods Sixteen male Wistar rats aged 4 to 5 months and 16 male rats aged 22 to 24 months were randomly divided into two groups: young control group, elderly control group, young hyperlipidemia group and elderly hyperlipidemia group (high fat diet) Each group of 8. After 8 weeks, glucose tolerance test was performed. Blood glucose and area under the curve of glucose (AUC) were measured at 0, 30, 60 and 120 min. Glucose infusion rate (GIR) was used to evaluate IR. Results Compared with the elderly control group and the young control group, the GIR of the elderly hyperlipidemia group and the young hyperlipidemia group were significantly decreased, and the skeletal muscle TG and LCACoA were significantly increased (P <0.05, P <0.01). Compared with the elderly control group, the blood glucose and AUC in the elderly hyperlipidemic rats at each time point were significantly different (P <0.05, P <0.01). GIR was negatively correlated with insulin, skeletal muscle TG, and LCACoA. Conclusion The increase of skeletal muscle TG and LCACoA content in aged and hyperlipidemic rats may be one of the reasons why IR is prone to occur in the elderly.