Effects of casomorphin or casein peptides on the blood glucose level in the diabetic rats | 酪啡肽及酪蛋白水解肽对糖尿病大鼠血糖的影响

صينى. 摘　　要：选用SD雄性大鼠50只,随机取42只作为糖尿病模型组,另8只为空白对照组。糖尿病模型组大鼠按60 mg・kg-1一次性腹腔注射链脲佐菌素（STZ）,空白组大鼠腹腔注射等体积生理盐水。分别于注射STZ后24 h和72 h剪尾取血,血糖仪测定所有大鼠的空腹（禁食8 h）血糖水平。取造模成功大鼠（血糖值≥11.1 mmol・L-1）32只,随机分为阳性对照组（蒸馏水灌胃）、β-酪啡肽7组（β-酪啡肽7灌胃）、水解肽组（酪蛋白水解肽灌胃）和酪蛋白组（酪蛋白溶液灌胃）,每12 h灌胃1次。每3 d空腹测血糖1次。连续灌胃15 d后断颈处死,取血浆、肝脏、心脏和腿肌等样品,观察血糖浓度以及其他影响血糖的重要指标的变化。结果显示：与阳性对照组相比,β-酪啡肽7和酪蛋白水解肽均能降低糖尿病大鼠的血糖浓度,提高血浆胰岛素含量,显著降低血浆胰高血糖素含量（P〈0.05）,显著增加了糖原的合成（P〈0.05）;而酪蛋白组大鼠血糖浓度、激素水平、糖原含量与阳性对照组无显著差异。提示：β-酪啡肽7和酪蛋白水解肽具有一定的降糖作用,其降低血糖的途径可能是通过提高胰岛素的分泌和促进肝、肌糖原的合成进行的;酪蛋白本身没有降糖作用。

إنجليزي. Fifty male SD rats were divided into two groups：a nondiabetic control（n=8）and a diabetic group（n=42）.Sreptozocin（STZ）was administered intraperitoneally（i.p.）at a single dose of 60 mg・kg-1 to diabetic group.The control rats were only injected with the citrate buffer.Collecting serum at 24 h and 72 h after STZ treatment,the development of diabetes was confirmed by measuring blood glucose levels.The rats with blood glucose level 11.1 mmol・L-1 or higher were considered to be diabetic and were used in the experiment.The diabetic rats（n=32）were randomly divided into four groups：positive control rats,β-casomorphin-7（β-CM7）treated diabetic rats,casein peptides treated diabetic rats,casein treated diabetic rats.Every 3 days of experimentation,blood samples were collected for biochemical estimations.On the last day of experiment,the animals were deprived of food overnight and sacrificed by cervical dislocation.Blood was collected in sterilized tubes with the anticoagulant.Then the liver,heart and leg muscle were removed.Observed were the changes of the blood glucose level and other important indicators which are associated with the blood glucose.The results showed after 15 days oral administration of β-CM7 or casein peptides,the elevated blood glucose level was reduced.The oral administration of β-CM7 or casein peptides to diabetic rats showed an increase in the level of plasma insulin,and the elevated plasma glucagon level was markedly reduced by the oral administration of β-CM7 or casein peptides compared with positive control rats.The blood glucose,plasma insulin,glucagon and glycogen level of casein peptides treated diabetic rats is as the same as those of the positive control rats.Thus,the results of the present study suggest that β-CM7 or casein peptides can decrease the blood glucose by elevating insulin secretion or promoting glycogen synthesis.Hypoglycemic effect of casein itself can not.