奶牛酮病与胰岛素抵抗关系探讨

为探讨奶牛酮病与胰岛素抵抗的关系,选取产后14 d的酮病组(T)16头和健康对照组(C) 24头奶牛,比较酮病与对照组在能量平衡、肝功能状况、氧化应激、胰岛素敏感性以及耐糖量试验的差异.结果显示:酮病奶牛机体处于能量负平衡状态；肝功能指标中酮病组奶牛血浆天门冬氨酸转移酶、直接胆红素含量极显著高于健康对照组(P＜0.01),总胆红素含量显著高于健康对照组(P＜0.05),胆碱酯酶含量极显著低于健康对照组(P＜0.01),总蛋白含量显著低于健康对照组(P＜0.05),丙氨酸氨基转移酶、间接胆红素、白蛋白、球蛋白含量与健康对照组差异不显著,表明病牛肝脏受到一定程度的损害；酮病组奶牛血浆丙二醛、超氧化歧化酶含量显著高于健康对照组(P＜0.05),表明病牛处于氧化应激状态；酮病奶牛血浆胰岛素敏感指数显著低于健康对照组(P＜0.05),表明病牛的胰岛素敏感性下降.葡萄糖耐量试验显示部分酮病奶牛血糖含量显著高于健康对照组(P＜0.05),在注射完葡萄糖120min后血糖浓度高达4.24 mmol/L,组间差异极显著(P=0.006),表明病牛存在胰岛素抵抗.奶牛酮病与胰岛素抵抗存在密切的关系,可能与肝功能与氧化应激有关.

Study on the relationship of ketosis and insulin resistance in dairy cows

To study the relationship between ketosis and insulin resistance during early lactation,16 ketosis (T) and 24 healthy control (C) cows were chosen from a intensive dairy farm.Blood samples from all cows were collected at 14 days postpartum during morning fasting.Differences in energy balance,liver function,oxidative stress,insulin sensitivity and glucose tolerance were analyzed between T and C.Results showed that,cows with keosis were in condition of negative energy balance.The level of plasma AST and DBIL raised significantly (P<0.01) in T group compared to C group,and plasma TBIL also increased significantly (P<0.05),but plasma CHE and TP decreased significantly (P<0.01 or <0.05),and there is no significantly change in plasma ALT,IBIL,ALB,and GLO,suggesting that cows with ketosis suffered from certain degree of liver function abnormality.In addition,level of plasma malondialdehyde (MDA) and superoxide dismutase (SOD) was significantly higher in T group than in C group (P<0.05),implied that cows affected ketosis experienced oxidative stress.Furthermore,plasma revised quantitative insulin sensitivity test (RQUICKI) was lower significantly in T group than in C group (P<0.05),indicated that cows with ketosis had low insulin sensitivity.Concentration of plasma Glc in T group were higher than in C group during glucose tolerance test (P<0.05),and plasma Glc concentration was still 4.24 mmol/L at 120 min after intravenous injection of 50% dextrose,which had a significant differences between two groups (P=0.006),showing that cows affected ketosis had insulin resistance.It is concluded that there is a closed relationship between ketosis and insulin resistance,which may be related to liver function and oxidative stress because both can cause insulin resistance.