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

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.