异育银鲫口服不同剂量葡萄糖后的代谢反应

METABOLIC RESPONSES OF ALLOGYNOGENETIC GBEL CARP AFTER ORAL ADMINISTRATION OF DIFFERENT DOSES OF GLUCOSE

  • 摘要: 平均体重为164±12g的异育银鲫(方正银鲫♀×兴国红鲤♂)禁食四周,以使肝糖原含量充分下降,然后灌喂不同剂量的葡萄糖,研究葡萄糖负荷后的代谢反应.实验结果表明,不管口服剂量是多少,异育银鲫在口服葡萄糖后都出现持久的高血糖;口服后1h血浆总氨基酸、甘油三酯和乳酸水平显著上升,然后迅速下降;肝糖原含量先降低,2h左右开始回升.血糖、总氨基酸、甘油三酯、乳酸及肝糖原的变化幅度也随口服剂量变化而变化:血糖升幅随口服剂量增加而加大;在口服后1h,总氨基酸含量随着口服剂量的增加而增加,甘油三酯和乳酸含量随着口服剂量的增加而减少,而在口服后2-10h内,口服剂量越高,总氨基酸、甘油三酯水平越低,乳酸水平越高;肝糖原含量随着口服剂量的增加而减少.上述结果提示异育银鲫在口服高剂量葡萄糖之初的1h内生长抑素和胰高血糖素水平较高,而胰岛素的分泌可能受到了抑制;推测当口服剂量较低时胰岛素则能正常分泌.

     

    Abstract: In this experiment, the variation of plasma level of glucose, total amino acids, triglyceride, lactate and liver glycogen were determined after different doses of glucose were oral administratered to allogynogenetic gibel carp in order to study the hormonal patten in regulation of carbohydrate metabolism in fish. Fish (mean weight:164±12g)were acclimated to experimental condition before fasted for four weeks to ensure the liver glycogen decreased to low level enough, followed by different doses of glucose administration. The doses of glucose oral administratered to fish were 55. 7(group Ⅰ), 111. 3(group Ⅱ), 167(group Ⅲ)mg per100g body weight, respectively. 20 to 30 fish were randomly sampled respectively before(0h)or 1, 2, 4, 6, 8, 10h after glucose administration. Blood was sampled from the caudal vein and then the plasma level of glucose, total amino acids, triglyceride, lactate were determined. The fish were then dissected rapidly and pancreatics were removed and pooled for glycogen determination. Results showed that plasma glucose increased significantly at 1h and peaked at 3h after glucose administratered, which still higher notably at 10h than at 0h ( P 0.05), regardless the glucose doses;The plasma level of all of total amino acids, triglyceride and lactate in group Ⅲ increased significantly at 1h ( P 0.05)and later decreased sharply, which were lower at 2h than at 0h. In group Ⅲ, a piece of little peak of total amino acids appeared at 8h while that of triglyceride and lactate appeared at 6h; Liver glycogen increased slowly after reduced significantly during the first 2hs. The change extents of plasma level of glucose, total amino acids, triglyceride, lactate and liver glycogen were varied with the doses of glucose administered. Plasma glucose increased with the increasing doses. At 1h the total amino acid was higher while triglyceride and lactate lower with the increasing doses and during 2-10h, however, the total amino acid and triglyceride were lower while lactate was higher. Liver glycogen decreased with increasing in glucose doses administratered. These results indicated that allogynogenetic silver crucian carp was glucose intolorance. High dose of glucose administratered result in a shift in metabolic flux towards an enhanced catabolism of stored body reserves, which is probably associated with an increase in plasma glucagon and somatostatin and an suppression of plasma insulin. As a result, the gluconeogenesis and glycogen catabolism were promoted. These data also suggested that the content of insulin increased at 2h when the gluconeogenesis were inhibited while the glycolysis enhanced. At about 6h, however, hormone which promoted catabolism such as plasma glucagon and somatostatin rising slightly again. It was indicated that if the dose of glucose administered was low enough (at least less than 55. 7mg per 100g body weight), the insulin would excrete normally, so, the dietary carbohydrate of allogynogenetic silver crucian carp should be in relatively low level in order to keep normal physiology states.

     

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