手把区域多肽及氯沙坦抑制左旋谷氨酸钠大鼠腹部脂肪组织还原型烟酰胺腺嘌呤二核苷酸磷酸氧化酶亚单位的表达

Handle region peptide and losartan decreasing the expression of subunits of nicotinamide adenine dinucleotide phosphate oxidase in celiac adipose tissue in rats neonatally treated with sodium L-glutamate

目的 探讨手把区域多肽（HRP）及氯沙坦对左旋谷氨酸钠（MSG）大鼠胰岛素敏感性的影响及探讨其对腹腔脂肪组织局部肾素血管紧张素系统（RAS）和还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶亚单位基因表达的影响.方法 将8周龄体重在250～300 g的MSG大鼠共24只采用完全随机法分为MSG对照组（MSG组,n=6）、HRP干预组（MSG-HRP组,n=6,1.0 mg·d-1·kg-1）、氯沙坦干预组（MSG-L组,n=6,450 mg/L于饮用水中）、HRP及氯沙坦联合干预组（MSG-HRP-L组,n=6）,干预4周,正常SD大鼠为对照组（Con组,n=6）.12周龄时予以行胰岛素耐量试验评估大鼠胰岛素敏感性,计算胰岛素注射后30 min与0 rain时血糖比值.测定单位质量腹腔脂肪组织（前）肾素、（前）肾素受体[（P）RR]和选择性血管紧张素Ⅱ1型受体（AT1R） mRNA的表达及血管紧张素-Ⅱ（Ang-Ⅱ）蛋白水平,测定NADPH氧化酶亚单位P47phox和P22phoxmRNA的表达情况.采用方差分析及LSD两两比较法进行统计学分析.结果 外源性胰岛素注射后计算30 min血糖与基础血糖的比值,MSG组最高（92％±12％）,与Con组（66％±8％）、MSG-HRP组（76％±5％）、MSG-L组（78％±5％）、MSG-HRP-L组（75％±10％）比较均有统计学差异（F=6.875,P＜0.05）.本研究未能检测到腹腔脂肪组织中（前）肾素mRNA的表达.MSG-HRP组、MSG-L组、MSG-HRP-L组（P） RR mRNA表达量分别是MSG组大鼠的1.92、3.19和1.90倍（F=9.805,P＜0.05）.MSG-HRP组、MSG-L组、MSG-HRP-L组AT1 R mRNA分别是MSG大鼠组表达量的72％、45％和53％（F=14.508,P＜0.05）.与MSG组比较,MSG-HRP组脂肪局部Ang-Ⅱ水平下调[分别为（36±8）比（56±4） ng/g蛋白,P＜0.05],但是MSG-L组和MSG-HRP-L组水平均明显升高[分别为（79±14）比（70±16）比（56±4） ng/g蛋白,F=14.864,均P＜0.05].MSG-HRP组、MSG-L组、MSG-HRP-L组腹腔脂肪组织中P47phox mRNA分别是MSG大鼠组表达量的65％、51％和43％（F=7.082,均P＜0.05）.p22pho mRNA分别是MSG大鼠组表达量的57％、40％和41％（F=9.810,均P＜0.05）.结论 HRP和氯沙坦均可改善MSG大鼠胰岛素敏感性,其机制可能是其减少脂肪组织局部Ang-Ⅱ的数量或抑制脂肪组织中局部Ang-Ⅱ的效应,抑制氧化应激,从而改善脂肪胰岛素抵抗.

Objective To investigate the effect of handle region peptide （HRP） on insulin sensitivity,local renin-angiotensin system and subunits of nicotinamide adenine dinucleotide phosphate （NADPH） oxidase in abdominal adipose tissue in the rats neonatally treated with monosodium L-glutamate （MSG）.Methods The eight-week-old MSG rats were randomly divided into MSG control group （MSG group,n =6）,HRP treated group （MSG-HRP group,n =6,1.0 mg · d-1 · kg-1 with mini-pump）,losartan treated group （MSG-L group,n =6,450 mg/L in drinking water） and HRP with losartan combined treated group （MSG-HRP-L group,n =6）.The period of treatment is four weeks.Normal SD rats （con group,n =6） served as control.At the age of 12 weeks,insulin tolerance test was performed to evaluate the insulin sensitivity.The blood glucose ratio of 30 min to 0 min after infusion of insulin was calculated.The mRNA levels of （Pro） renin,（Pro） renin receptor （（P） RR）,angiotensin type 1 receptor （AT1R） and subunits of NADPH oxidase,including p47phox and p22phox in abdominal adipose tissue were measured by realtime PCR,and the protein level of angiotensin-Ⅱ （Ang-Ⅱ） was measured by ELISA.ANOVA and LSDtest was performed to estimate difference between groups.Results The ratio of blood glucose concentration 30 min after insulin injection to the basic blood glucose concentration was calculated.The MSG group （92％± 12％） had the highest level of the ratio and had statistic difference with the Con group （66％ 8％）,MSG-HRP group （76％ ±5％）,MSG-L group （78％ ±5％） and MSG-HRP-L group （75％ 10％） （F =6.875,all above P ＜ 0.05）.The （pro） renin mRNA was not detected in abdominal adipose tissue.The MSG-HRP group,MSG-L group,and MSG-HRP-L group had 1.92,3.19 and 1.90 times （F=9.805,all P ＜ 0.05） of （P） RR mRNA expression respectively and had 72％,45％,and 53％ （F =14.508,all P ＜0.05） of AT1R mRNA expression respectively compared to the MSG group.Compared to the MSG group （（56 ± 4） ng/g protein）,local adipose tissue level of Ang-Ⅱ decreased in the MSG-HRP group （（36 ± 8） ng/g protein,P ＜ 0.05）,and obviously increased in the MSG-L group （（79 ± 14） ng/g protein,P ＜ 0.05） and MSG-HRP-L group （（70 ± 16） ng/g protein,F =14.864,all above P ＜ 0.05）.The MSG-HRP group,MSG-L group and MSG-HRP-L group had 65％,51％ and 43％ （F =7.082,all above P ＜ 0.05） of p47phox mRNA expression respectively and had 57％,40％ and 41％ （F =9.810,all above P ＜ 0.05） of p22phox mRNA expression respectively compared to the MSG group.Conclusion Both of HRP and losartan ameliorated insulin sensitivity with the possible mechanism of decreasing the level of Ang-Ⅱ or inhibiting the effect of Ang-Ⅱ in abdominal adipose tissue,and hence inhibiting oxidative stress.