卫生研究

目的 探讨自由摄食条件下脂肪供能比为35%时不同脂肪酸构成的食用油对中老年大鼠糖脂代谢的影响。方法 将50只8～10月龄雄性大鼠按体重随机分为5组，即对照组(喂AIN93M饲料)、单不饱和脂肪酸(monounsaturated fatty acid, MUFA)组(喂高油酸葵花籽油饲料)、多不饱和脂肪酸(polyunsaturated fatty acid, PUFA)组(喂普通葵花籽油饲料)、动物性饱和脂肪酸(animal-based saturated fatty acid, ASFA)组(喂猪油饲料)和植物性饱和脂肪酸(vegetable-based saturated fatty acid, VSFA)组(喂椰子油饲料),连续喂养12周。实验期间每周称量大鼠体重和摄食量，第12周行口服葡萄糖耐量实验。实验结束，双能X线吸收测量法检测大鼠体脂和腹部脂肪含量；腹主动脉取血，测定血清空腹血糖和血脂指标；取大鼠肾周脂肪、附睾脂肪称重，并分别计算与体重的比值；HE染色观察大鼠肝脏病理学。结果 与对照组相比，4个实验组大鼠总摄食量均降低，VSFA组大鼠能量摄入以及PUFA组和VSFA组大鼠能量利用率增加(P<0.05)。与对照组相比，MUFA组的TG水平降低，PUFA组的甘油三酯、总胆固醇、高密度脂蛋白胆固醇血症、游离脂肪酸和非高密度脂蛋白胆固醇水平均显著降低，ASFA组的高密度脂蛋白胆固醇和游离脂肪酸水平也有所下降，VSFA组的低密度脂蛋白胆固醇水平则显著降低(P<0.01,P<0.05)。PUFA组和ASFA组大鼠的空腹血糖低于对照组(P<0.05)。MUFA组和VSFA组大鼠肾周脂肪和附睾周脂肪均高于对照组(P<0.01,P<0.05),ASFA组大鼠肾周脂肪高于对照组(P<0.05),MUFA组大鼠的腹部和全身脂肪含量显著高于对照组(P<0.01,P<0.05)。VSFA组肝脏中的脂质空泡显著多于对照组，而其他组则介于两者之间。结论 在自由摄食、脂肪供能比为35%的条件下，PUFA油脂有助于改善糖脂代谢水平，降低心血管疾病的发病风险。MUFA油脂会导致大鼠腹部脂肪和内脏脂肪的增加，ASFA油脂具有降低血糖的作用，VSFA油脂加剧大鼠肝脏脂肪的积聚。

OBJECTIVE Discussion on the effects of edible oils with different fatty acid compositions on glucose and lipid metabolism in middle-aged and elderly rats under free-feeding conditions with a fat energy ratio of 35%.METHODS The experiment randomized 50 male rats aged 8-10 months into five groups: a control group(NC, fed AIN93 M diet), a monounsaturated fatty acid(MUFA) group(fed high oleic sunflower oil diet), a polyunsaturated fatty acid(PUFA) group(fed regular sunflower oil diet), an animal-based saturated fatty acid(ASFA) group(fed lard diet), and a vegetable-based saturated fatty acid(VSFA) group(fed coconut oil diet). The rats were fed continuously for 12 weeks. During the experiment, the body weight and food intake of the rats were measured weekly. At the end of the 12th week, an oral glucose tolerance test was performed on the rats. After the experiment, dual-energy X-ray absorptiometry(DEXA) was used to measure the body fat and abdominal fat content of the rats. Blood samples were collected from the abdominal aorta for the determination of fasting blood glucose and blood lipid levels. The perirenal fat and epididymal fat of rats were removed and weighed, and the ratios of these fat masses to the body weight were calculated respectively. Additionally, HE staining was used to observe the liver pathological lipids of the rats.RESULTS Body weight and food intake result showed that compared to the NC group, the total food intake of rats in all four experimental groups decreased. The energy intake of the VSFA group and the energy utilization of the PUFA and VSFA groups increased, with these differences being statistically significant(P<0.05). In terms of blood lipid levels, compared to the NC group, the the triglyceride(TG) level in the MUFA group decreased, while the TG, total cholesterol, high density lipoprotein cholesterol(HDL-C), nonesterified fatty acid(NEFA)and Non-HDL-C levels in the PUFA group significantly decreased. The HDL-C and NEFA levels in the ASFA group also decreased, and the low density lipoprotein cholesterol(LDL-C) level in the VSFA group significantly decreased, all with statistically significant differences(P<0.01 or P<0.05). In terms of blood glucose levels, the FBG levels of rats in the PUFA and ASFA groups were lower than in the NC group(P<0.05). The perirenal and epididymal fat masses of rats in the MUFA and VSFA groups were higher than those in the control group(P < 0.01,P < 0.05). The perirenal fat mass of rats in the ASFA group was higher than that in the NC group(P<0.05). The abdominal and total body fat content of rats in the MUFA group was significantly higher than in the NC group(P<0.01, P<0.05). Hepatic histopathological result showed that the lipid vacuoles in the liver of the VSFA group were significantly more than in the NC group, while that in the other groups were between the two.CONCLUSION Under the condition of ad libitum feeding and a fat energy contribution ratio of 35%,PUFA oil are beneficial for improving glucose and lipid metabolism levels, thereby potentially reducing the risk of cardiovascular disease. MUFA oil may lead to an increase in abdominal and overall body fat in rats, ASFA oil may help lower blood glucose levels, while VSFA oil may exacerbate the accumulation of liver fat in rats.