| The aim of this study were, to determine the metabolism of glucose under the condition of starvation. Two different parts were included in this study. Firstly, we investigated the effects of short-term starvation and refeeding with different time courses on body parameters , hepatosomatic index (HSI), glycogen and serum glucose in juvenile Parabramis pekinensis. The fish were randomly allocated into control and treatment groups (20±1)℃, control group was sustained fed, treatment groups were starved for 0, 1, 4, 7, 12 d and starved for 12 d then refed for 1, 4, 7, 15 d respectively. Samples were taken after the process. Secondly, juvenile Silurus meridonalis were starved for 0, 1, 2, 4, 8 w, and then sampled. The body parameters, hepatosomatic index (HSI), glycogen ,serum glucose and specific activities of hepatic enzymes were mensurated respectively.The results as follows:1. During the starvation, the body weight of juvenile Parabramis pekinensis decreased significantly (p<0.05); after refeeding for four days, it had returned to the original value(p>0.05). During the whole experiment, the body condition and body length did not change significantly in juvenile Parabramis pekinensis (p>0.05). In juvenile Silurus meridonalis, under the condition of starvation, the body condition decreased significantly (p<0.05), and the other two indices did not change significantly (p>0.05).2. As the starvation continued, HSI of juvenile Parabramis pekinensis decreased quickly and significantly (p<0.05); after refeeding for fifteen day, it had returned to the original value.In juvenile Silurus meridonalis, the indices behaved a same descendent direction during the starvation (p<0.05), after fasting for one week, it had dropped to 71.35%, markedly bellowed original value (p<0.05).3. Under the condition of starvation, serum glucose fell significantly (p<0.05); after refeeding ,it rose very fleetly (p<0.05), for instance, after refeeding for one day, it had gotten back to the original value (p>0.05). And there were no differences between the two groups, the control group and the treatment group during the whole experiment (p>0.05).When starved for four weeks, serum glucose of juvenile Silurus meridonalis was(20.25±2.77)mg·100ml-1 , which had fallen 53.32%, began to bellow the original value (p<0.05).4. During the starvation and refeeding, liver glycogen of juvenile Parabramis pekinensis declined significantly and rose quickly respectively (p<0.05), after refeeding for one day, it had goone back to the original value (p>0.05). Liver glycogen of juvenile Silurus meridonalis decreased significantlyduring the starvation (p<0.05).5. The content of muscle glycogen in juvenile Parabramis pekinensis went up during the whole experiment, whereas it declined markedly in juvenile Silurus meridonalis (p<0.05). In juvenile Silurus meridonalis, it was under the original value after starved for one weeks (p<0.05); later continued to decline, but had a little range and retained at the same level (p>0.05).6.In the state of starvation, the specific activities of hepatic enzymes of HK,GDH and GK all presented a similar descendent trend in juvenile Silurus meridonalis (p<0.05). Since starved for four weeks, they all had begun to bellow the original value (p<0.05), had fallen 41.64%,43.02% and 41.11% respectively; when starved for eight weeks ,the values had reached to the lowest level (p<0.05). At the beginning, the specific activities of the three enzymes had marked differences (p<0.05). The value of GDH was more higher than the other twos, which were on the same level (p>0.05); as starvation continued, there were no visible differences among the three values (p>0.05).In conclusion:1. During the starvation, the fish mainly used glucide as energy source, mobilized the substances in liver firstly and the change of liver glycogen had a direct relationship with the stability of serum glucose both in juvenile Parabramis pekinensis and Silurus meridonalis .2. In starved state, both in juvenile Parabramis pekinensis and Silurus meridonalis, the diversification of serum glucose was steady, and the change of liver glycogen was faster than serum glucose. Hence, we could say that the change of liver glycogen had a direct relationship with the stability of serum glucose. 3. Under the condition of starvation, muscle glycogen behaved an ascending trend in juvenile Parabramis pekinensis, whereas a descendent trend in juvenile Silurus meridonalis. There might be two reasons for this differences. Firstly, one of the two kinds of experimental fish was herbivorous, and the other one was predatory, that was to say that they had different physiological mechanism. Secondly, juvenile Parabramis pekinensis was treated for a shorter period than Silurus meridonalis, some differences of the indices might not represent yet.4. Starvation had a marked effect upon the specific activities of HK and GK in juvenile Silurus meridonalis (p<0.05), whereas, short-time starvation (two weeks) had a trivial effect (p>0.05) . |
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