长期高脂饲养对大鼠葡萄糖刺激的胰岛素分泌的影响

The effect of a long term high fat feeding on glucos e-stimulated insulin secretion in rats

目的 观察膳食总热量正常、脂肪含量长期增高饲养对正常大鼠葡萄糖刺激的胰岛素分泌的影响。方法 8周龄雄性SD大鼠 1 9只 ,分为正常饲养组 (NC ,n =1 0 )和高脂饲养组 (HF ,n =9)。两组大鼠每日摄食总热量相等 ,但饲料中脂肪占总热量 (31 0kJ/d)的百分比不同 (NC组脂肪占 1 3 % ,HF组脂肪占 59% )。观察大鼠每月体重、空腹血糖 (FBG)、空腹胰岛素 (FINS)、空腹游离脂肪酸 (FFFA)的变化。饲养至 36周龄 ,作静脉葡萄糖耐量试验 (IVGTT) ,观察两组大鼠葡萄糖刺激的胰岛素分泌 ,尤其是胰岛素分泌的第一时相的差异。结果 高脂饲养后大鼠出现明显的腹型肥胖 (内脏脂肪占体重百分比分别为 :HF组 1 0 .7% ,NC组 5 .3 % ,P <0 .0 0 1 ) ,血FFFA升高〔HF组 (1 .60± 0 .36)mmol/L ,NC组 (0 .59± 0 .1 2 )mmol/L ,P <0 .0 0 1〕。 36周龄时 ,IVGTT中 5、 1 0、 30min血糖 (BG)HF组显著高于NC组〔5min :(1 7.3± 0 .7)mmol/Lvs(1 6 .0± 0 .7)mmol/L ,P <0 .0 5 ;1 0min :(1 4 .6± 0 .8)mmol/Lvs (1 2 .7± 1 .0 )mmol/L ,P <0 .0 0 1 ;30min :(9.4± 1 .6)mmol/Lvs (6 .6± 1 .4)mmol/L ,P <0 .0 1〕。 5、1 0min血胰岛素HF组显著低于NC组〔5min :(734 .7± 1 .5) pmol/Lvs (1 938.4± 1 .4)pmol/L ,P <0 .

Objective To o bs erve the effect of a long term high fat feeding with normal total calorie intake on glucose stimulated insulin secretion in rats. Methods Normal male SD rats (8 weeks old) were divided into two groups takin g either normal chow (NC, 13% of calories as fat, n=10), or isocaloric high-fat diet (HF, 59% of calories as fat, n=9). Each rat was given 310 kJ/d. The insulin secretory function of β cells was ass essed by intravenous glucose tolerance test (IVGTT) in 36 weeks old rats. Results Rats taking HF had significantly higher plasm a fasting free fatty acids (FFFA) 〔HF: (1.60±0.36)mmol/L, vs NC (0.59±0.12)mmol/L,P<0.001〕 and developed severe vis ceral obesity compared with NC rats. 〔body weight: (642.8±39.5)g vs (535.5±65.2)g,P<0.001; visceral fat mass: (68.6 ±8.4)g vs (27.9±4.9)g,P<0.001; viscer al fat mass/body weight: (10.7±1.4)% vs (5.3±1.6)%, P<0.001〕. There were no differences in basal blood glucose (BG) and insulin levels between HF and NC. But 5 min, 10 min and 30 min BG levels by IVGTT were significantly higher in HF than in NC.〔(17.3±0.7)mm ol/Lvs (16.0±0.7)mmol/L, P<0.05; (14.6±0.8)mmol/L vs (12.7±1.0)mmol/L, P<0.001; (9.4±1.6)mmol/L vs (6.6±1.4)mmol/L,P<0.01〕. Five min and 10 min plasma insulin levels were signi ficantly lower in HF than in NC. 〔(734.7±1.5)pmol/L vs (1 938.4±1.4)pmol/L,P<0.001; (875.4±1.6)pmol /L vs (1485.6±1.5)pmol/L,P<0.05〕. Sixty min plasma insulin levels were significantly higher in HF tha n in NC. 〔(676.9±1.6)pmol/L vs (411.8±1.7) pmol/L,P<0.05〕. Conclusion High fat fee ding with normal total colorie intake results in higher FFFA and inhibits acute insulin response to intravenous glucose in rats. The high fat feeding rats also display obvious visceral obesity.