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1.
Physiological responses of milkfish (Chanos chanos) under cold shock and acclimation were investigated. The experimental milkfish, a warm-water teleost, were initially acclimated at 25 °C and then transferred directly to 15 °C; stress responses of this species were monitored for 1 week. Parameters monitored included plasma glucose, lactate, and lipids, as well as stearoyl-CoA desaturase activity and fatty acid compositions of hepatic membranes. All parameters showed significant changes in the process of cold acclimation. A hyperglycemic response indicated by a notable and steady increase in plasma glucose levels from 85 mg dl−1 to the highest level of 458.2 mg dl−1 in 24 h was followed by a rapid decline thereafter. The elevation in plasma glucose content under cold shock resulted from gluconeogenesis and glycogenolysis, indicated by correlated changes in plasma glucose with fructose-1,6-biphosphatase and phosphorylase a activities. Plasma lactate concentrations remarkably increased from 47 mg dl−1 on day 0 to 149.6 and 120.4 mg dl−1 on days 1 and 2, respectively, and then rapidly declined to the same level as the control thereafter. In contrast, plasma lipids increased gradually from 44.8 mg dl−1 to 191 mg dl−1 over the 5-day acclimation period, followed by a declining trend from day 6 on. Furthermore, changes in monounsaturated fatty acids were highly correlated with those of stearoyl-CoA desaturase activities in hepatic microsomes of milkfish during cold acclimation. Results indicate that in milkfish subjected to cold stress, plasma hyperglycemic and hyperlactemic responses can be used as acute stress indicators, and plasma lipids can be used as a chronic stress indicator.  相似文献   

2.
SUMMARY: Common carp Cyprinus carpio were administered intraperitoneally with 10 μmol epinephrine per 100 g bodyweight, and enzyme activities and metabolic intermediate concentrations were determined in the hepatopancreas and muscle. Glycogen phosphorylase a (GPase a) activity together with cyclic AMP (cAMP) concentration was increased, and glycogen content was decreased in the hepatopancreas and muscle at 2 h after the administration. The epinephrine administration also increased hepatopancreatic glucose-6-phosphatase and fructose-1,6-biphosphatase activities as well as serum glucose, lactate, and free amino acid concentrations. Furthermore, its administration increased phosphofructokinase activity together with lactate, fructose-6-phosphate, adenosine-5'-monophosphate, and adenosine-5'-diphosphate concentrations and decreased citrate concentration in the muscle. Thereafter, almost all parameter concentrations in the hepatopancreas and muscle recovered to the pre-administered levels during 24 h after the administration. These results suggest that epinephrine administration enhanced glycogenolysis and gluconeogenesis in the hepatopancreas, and released glucose into the bloodstream to supply it to the muscle. The blood glucose together with muscle glycogen seems to be metabolized through enhanced glycolysis in the muscle.  相似文献   

3.
王猛强  黄文文  周飘苹  金敏  邱红  周歧存 《水产学报》2015,39(11):1690-1701
本实验旨在研究不同蛋白质和小麦淀粉水平对大黄鱼生长性能、肝脏糖酵解和糖异生关键酶活性、血清指标、糖原含量及消化酶活性的影响。采用2×3双因素实验设计,共配制6组饲料,包含2个蛋白质水平(41%、46%)和3个小麦淀粉水平(10%、20%、30%),选取初重约为(14.84±0.16) g的大黄鱼900尾,随机分为6组(每组3个重复,每个重复50尾),进行8周的养殖实验。实验结果表明:饲料蛋白质和小麦淀粉水平的交互作用对大黄鱼增重率和特定生长率无显著影响(P>0.05),且在相同的饲料蛋白质水平下,饲料小麦淀粉水平对大黄鱼增重率和特定生长率无显著影响(P>0.05)。饲料蛋白质和小麦淀粉的交互作用对大黄鱼肝脏6-磷酸果糖激酶(phosphofructokinase,PFK)、丙酮酸激酶(pyruvate kinase,PK)、果糖-1,6-二磷酸酶(fructose-1,6-bisphosphatase,FBPase)活性有显著影响(P<0.05),但对葡萄糖激酶(glucokinase,GK)、葡萄糖-6-磷酸酶(glucose-6-phosphatase,G6Pase)、磷酸烯醇式丙酮酸羧激酶(phosphoenolpyruvate,PEPCK)活性无显著影响(P>0.05)。当饲料蛋白质水平为41%时,饲料小麦淀粉水平对葡萄糖激酶、6-磷酸果糖激酶和果糖-1,6-二磷酸酶活性有显著影响(P<0.05),且果糖-1,6-二磷酸酶活性随着饲料小麦淀粉水平的升高呈下降趋势,但对丙酮酸激酶、葡萄糖-6-磷酸酶、磷酸烯醇式丙酮酸羧激酶活性无显著影响(P>0.05);当饲料蛋白质水平为46%时,饲料小麦淀粉水平对葡萄糖激酶、6-磷酸果糖激酶、丙酮酸激酶、果糖-1,6-二磷酸酶活性有显著影响(P<0.05),且葡萄糖激酶、6-磷酸果糖激酶、丙酮酸激酶均随饲料小麦淀粉水平的升高呈上升趋势,但对葡萄糖-6-磷酸酶和磷酸烯醇式丙酮酸羧激酶活性无显著影响(P>0.05)。实验表明,大黄鱼在高蛋白质水平下能够有效调节糖酵解和糖异生关键酶活性,降低血糖含量及丙氨酸转氨酶、天冬氨酸转氨酶活性,并且未显著影响增重率;在低蛋白质水平,血糖含量和肝糖原含量随小麦淀粉水平的升高呈上升趋势,但增重率随着饲料小麦淀粉水平的升高呈上升趋势,表明在低蛋白质水平下高小麦淀粉水平对大黄鱼的生长有一定的改善作用。  相似文献   

4.
草鱼、银鲫和青鱼捕捞后的应激反应   总被引：2，自引：0，他引：2  
姜丹莉  林雅云  吴玉波  王岩 《水产学报》2016,40(9):1479-1485
分别评价了捕捞对草食性(草鱼)、杂食性(银鲫)和肉食性(青鱼)鲤科鱼类血液指标(血浆史质醇、葡萄糖和乳酸浓度)、肝糖原含量和两种肝脏糖酵解酶(己糖激酶和丙酮酸激酶)活性的影响。结果显示:草鱼、银鲫和青鱼捕捞后血浆史质醇、葡萄糖和乳酸浓度均显著升高;草鱼和青鱼捕捞后2 h时肝糖原含量呈下降趋势,但银鲫捕捞前、后肝糖原含量未出现显著变化;捕捞前、后青鱼血糖浓度显著高于草鱼和银鲫。银鲫肝糖原含量显著高于草鱼和青鱼,其捕捞后血浆葡萄糖和乳酸浓度增加幅度较小,这意味着捕捞后银鲫应激反应强度相对较低。草鱼和银鲫捕捞后肝脏己糖激酶和丙酮酸激酶活性未发生显著变化,青鱼捕捞后2 h己糖激酶活性显著下降,这意味着捕捞应激后血糖升高未导致草鱼、银鲫和青鱼的肝脏糖酵解酶活性增强。  相似文献   

5.
The aim of this study was to assess the role of soluble non-starch polysaccharide (guar gum) on white sea bream Diplodus sargus, glucose and lipid metabolism. A control diet was formulated to contain 40 % crude protein, 14 % crude lipids and 35 % pregelatinized maize starch, and three other diets were formulated similar to the control diet except for guar gum, which was included at 4 % (diet GG4), 8 % (diet GG8) or 12 % (diet GG12). Diets were fed to the fish for 9 weeks on a pair-feeding scheme. Guar gum had no effect on growth performance, feed efficiency, glycaemia, cholesterolaemia and plasma triacylglyceride levels. Hepatic glucokinase and pyruvate kinase activities, liver glycogen content and liver insulin-like growth factor-I gene expression were not affected by dietary guar gum, while fructose-1,6-bisphosphatase activity was lower in fish fed guar gum–supplemented diets. Hepatic glucose-6-phosphate dehydrogenase activity was higher in fish fed diets GG4 and GG8 than in the control group. Overall, data suggest that in contrast to mammals guar gum had no effect on white sea bream glucose utilization and in lowering plasma cholesterol and triacylglyceride levels. However, it seems to contribute to lower endogenous glucose production.  相似文献   

6.
ABSTRACT: The responses of enzyme activities and metabolic intermediate concentrations to a long burst of exercise and following resting were examined in muscle and the hepatopancreas of carp Cyprinus carpio . A 15 min burst of exercise made the fish so exhausted that they could not swim any more. In muscle, the exercise decreased glycogen content significantly and increased lactate content significantly, resulting in a lowered pH. Furthermore, the burst of exercise decreased phosphofructokinase (PFK) activity significantly, although it changed adenosine-5'-monophosphate, adenosine-5'-diphosphate, adenosine-5'-triphosphate, fructose-6-phosphate and citrate concentrations within ranges that could activate PFK. In the hepatopancreas, the exercise increased glucose-6-phosphatase and fructose-1,6-bis-phosphatase activities, and glucose and lactate concentrations in the serum, and it decreased glycogen content. Even at 3 h resting after the burst of exercise, the fish had not completely restored many parameters. These results suggest that although the fish tried to enhance in vivo muscular glycolysis through the activation of PFK by changes in metabolic intermediate concentrations, glycolysis seemed to decrease markedly through the inhibition of PFK as a result of the lowered pH. However, the hepatopancreas made a contribution to muscular exercise through glucose supplementation by enhanced gluconeogenesis and glycogenolysis, indicating the presence of an interdependence of carbohydrate metabolism between muscle and the hepatopancreas in the fish.  相似文献   

7.
An 8-week feeding trial was conducted to evaluate the effect of dietary carbohydrate sources on the growth performance and hepatic carbohydrate metabolic enzyme activities of juvenile cobia. Six experimental diets were formulated to contain 20% glucose, sucrose, maltose, dextrin, corn starch and wheat starch respectively. The results indicated that fish fed the wheat starch and dextrin diets showed significantly better weight gain, specific growth rate and protein efficiency ratio compared with those fed the other diets. However, fish fed the glucose diet had a significantly lower survival and condition factor than those fed the other diets. There were significant differences in the total plasma glucose and triglyceride concentration in fish fed diets with different dietary carbohydrate sources. Haematocrit, haemoglobin, red blood cell and leucocytes were significantly affected by the dietary carbohydrate sources. The activities of glucose-6-phosphate dehydrogenase (G6PD), 6-phosphofructokinase (PFK) and fructose-1,6-bisphosphatase (FBPase) were significantly affected by the dietary carbohydrate sources, while fish fed the glucose diet showed higher G6PD, PFK and FBPase activities than those fed the other diets. These data indicated that dextrin and wheat starch were the most optimal carbohydrate sources for juvenile cobia.  相似文献   

8.
Stress has a considerable impact on welfare and productivity of fish, and blood glucose level of fish may be a factor modulating stress response. This study evaluated the effect of blood glucose level and handling on acute stress response of grass carp Ctenopharyngodon idella. Fish were intraperitoneally injected with glucose at 0, 0.2, 0.5, and 1.0 mg g?1 body mass (BM) and then were exposed to handling for 5 min. Glucose injection resulted in increase of plasma glucose level and liver glycogen content and decrease of plasma lactate level. Handling resulted in increase of plasma levels of cortisol, glucose, and lactate and plasma lactic dehydrogenase (LDH) activity and decrease of liver glycogen content. At 1 h post-stress, the plasma cortisol level was lower in the stressed fish injected with glucose at 0.5 mg g?1 BM than the stressed fish injected with glucose at 0, 0.2, and 1.0 mg g?1 BM. No significant differences were found in the activities of phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate kinase (PK) in the liver between the stressed and unstressed fish, regardless of the dose of glucose injection. At 1 h post-stress, the liver glucose-6-phosphatase (G6Pase) activity was higher in the fish without glucose injection than in the fish injected with glucose. This study reveals that blood glucose level can affect stress response of grass carp by modulating cortisol release and glucose homeostasis through glycogen metabolism and gluconeogenesis in the liver.  相似文献   

9.
Nutritional regulation of hepatic glucose metabolism in fish   总被引：2，自引：0，他引：2  
Glucose plays a key role as energy source in the majority of mammals, but its importance in fish appears limited. Until now, the physiological basis for such apparent glucose intolerance in fish has not been fully understood. A distinct regulation of hepatic glucose utilization (glycolysis) and production (gluconeogenesis) may be advanced to explain the relative inability of fish to efficiently utilize dietary glucose. We summarize here information regarding the nutritional regulation of key enzymes involved in glycolysis (hexokinases, 6-phosphofructo-1-kinase and pyruvate kinase) and gluconeogenesis (phosphoenolpyruvate carboxykinase, fructose-1,6-bisphosphatase and glucose-6-phosphatase) pathways as well as that of the bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase. The effect of dietary carbohydrate level and source on the activities and gene expression of the mentioned key enzymes is also discussed. Overall, data strongly suggest that the liver of most fish species is apparently capable of regulating glucose storage. The persistent high level of endogenous glucose production independent of carbohydrate intake level may lead to a putative competition between exogenous (dietary) glucose and endogenous glucose as the source of energy, which may explain the poor dietary carbohydrate utilization in fish.  相似文献   

10.
The effect of dietary carbohydrate complexity on growth, feed utilization and activity of selected key liver enzymes of intermediary metabolism were studied in gilthead sea bream juveniles. Four isonitrogenous (50% crude protein) and isolipidic (16% crude lipids) diets were formulated to contain 20% of pregelatinized maize starch, dextrin, maltose or glucose. Triplicate groups of fish (117 g initial weight) were fed each diet to near satiation during 6 weeks. No effect of dietary carbohydrate on growth was noticed. Feed efficiency was lower in fish fed the glucose diet than the maltose and dextrin diets. The lowest protein efficiency ratio was observed in fish fed the glucose diet. Six hours after feeding, glycemia was higher in fish fed the glucose diet than the maltose and starch diets. Liver glycogen content was unaffected by dietary carbohydrate complexity. Hepatic glucokinase (GK) activity was higher in fish fed the glucose and the maltose diets, while higher pyruvate kinase (PK) activity was recorded in fish fed the glucose diet than in fish fed the starch diet. Fructose-1,6-bisphosphatase (FBPase) and glucose-6-phosphate dehydrogenase (G6PD) activities were higher in fish fed the starch diet compared to dextrin and glucose diets. Data suggest that dietary glucose and maltose are more effective than complex carbohydrates in enhancing liver glycolytic activity. Dietary glucose also seems to be more effective than starch in depressing liver gluconeogenic and lipogenic activities. Overall, dietary maltose, dextrin or starch was better utilized than glucose as energy source by gilthead sea bream juveniles.  相似文献   

11.
A growth trial was conducted to determine the effects of dietary carbohydrate level on growth performance, feed utilization and metabolism of juvenile spotted babylon. Six isonitrogenous and isoenergetic experimental diets (48% crude protein and 15 MJ kg− 1 diet) using wheat starch as the carbohydrate source, were formulated to contain six carbohydrate levels. Triplicate groups of 45 animals (initial average weight, 168.39 ± 0.69 mg) were stocked in 120-l tanks and fed to apparent satiation twice daily for 10 weeks. Growth performance and feed utilization were significantly affected by dietary carbohydrate level. Maximum weight gain and specific growth rate occurred at 20% dietary starch inclusion, survival and soft body to shell ratios were not significantly different among diets. There were significant differences in protein, lipid, moisture and glycogen content in soft body. Glycogen content in soft body was positively correlated with dietary starch level. The activities of glucose-6-phosphate dehydrogenase and fructose-1,6-bisphosphatase were significantly affected by dietary starch level, with both peaking in the 20% treatment; however, there were no significant differences in 6-phosphofructokinase activity in any treatment. Quadratic regression analysis of weight gain against dietary starch level indicated that the optimal dietary carbohydrate level for maximum weight gain of juvenile spotted babylon is 27.1% of dry diet.  相似文献   

12.
The effect of higher packing density and increased duration of transport on the survival and key metabolic enzymes of Labeo rohita fry was investigated. L. rohita fry (length 40 ± 5 mm, weight 0.60 ± 0.13 g) were packed in two different densities 40 and 80 g/l and sampled at 0, 12, 24, and 36 h after packing. Results showed that packing density and length of confinement severely affected the survival of the fry. The whole-body glucose level and the activities of the enzymes, lactate dehydrogenase (LDH), malate dehydrogenase (MDH), glucose-6-phosphatase (G6Pase), fructose-1, 6-bisphosphatase (FBPase), aspartate amino transferase (AST), alanine amino transferase (ALT), and adenosine triphosphatase (ATPase) assayed from the fish whole-body significantly (P < 0.05) increased due to increase in the length of the confinement. However, acetylcholine esterase (AchE) activity decreased significantly (P < 0.05) with increase in the length of confinement. Similarly, higher packing density also significantly (P < 0.05) increased the glucose level and activities of all these enzymes (except AchE). The results revealed that both higher packing density and increased transportation duration mobilize protein resources for glucose production via gluconeogenesis and subsequently activate the glycolysis pathway for energy. The rise in the ATPase activity indicates disruption of the osmoregulatory function and the role of this enzyme in ameliorating it. Overall results suggest that normally practiced packing density of 40 g/l is optimum up to 24-h duration for seed transportation.  相似文献   

13.
本研究探讨了感染水霉病后草鱼(Ctenopharyngodon idellus)的血液生化特性和肌肉泛素-蛋白酶体系统(UPS)活性变化。随机选取患病和健康草鱼各10尾,测定血清葡萄糖(GLU)、白蛋白(ALB)、总蛋白(TP)、胆固醇(CHO)及甘油三酯(TG)含量和乳酸脱氢酶(LDH)、碱性磷酸酶(ALP)、谷草转氨酶(AST)及谷丙转氨酶(ALT)活性,检测肌肉nrf2、hsp70、hsp90和UPS相关基因表达,并定量测定了肌肉组织泛素化蛋白水平。结果显示,感染水霉病草鱼的血清CHO、ALB、TP和TG浓度显著下降,AST和LDH活性显著提高,患病草鱼肌肉组织nrf2、hsp70和hsp90的mRNA表达量显著升高。水霉病显著上调了肌肉chip、ub、psma2、psmc1、murf1和mafbx的mRNA表达水平和泛素化蛋白含量。感染水霉病改变了草鱼血清生化指标,诱导草鱼机体产生细胞应激反应,显著上调了骨骼肌泛素-蛋白酶体系统的活性。研究结果可为水霉病的诊断和防治提供科学的参考依据。  相似文献   

14.
High-energy diets for white sturgeon, Acipenser transmontanus Richardson   总被引：1，自引：0，他引：1  
Four diets formulated for salmon were fed to 0.11 kg white sturgeon, Acipenser transmontanus Richardson, for 8 weeks. Dietary compositions ranged from 258 to 402 g lipid kg−1, 535–378 g protein kg−1 and 22.7–14.4 g protein MJ−1 gross energy.
Fish in all treatments grew rapidly, utilized the diets efficiently and had body compositions similar to what has been found in previous studies, but there were some dietary effects. Sturgeon fed the diet with the highest lipid content and lowest protein/energy ratio had lower ( P < 0.05) specific growth rate, feed efficiency, and liver moisture and protein contents, and 6-phosphogluconate dehydrogenase activity, but higher liver lipid contents than fish fed the other three diets. Condition factor, organ to body weight ratios, whole-body and plasma concentrations of protein, glucose and triglyceride, and liver glucose-6-phosphate dehydrogenase, isocitrate dehydrogenase and malic enzyme activities did not differ significantly among dietary treatments. This suggests that white sturgeon subyearlings can utilize diets with high lipid contents (258–357 g kg−1) to display good growth without major adverse effects on body composition and liver lipogenic enzyme activities.  相似文献   

15.
黄岩  李建  王学习  王琨  叶继丹 《水产学报》2017,41(5):746-756
为了探讨饲料蛋白质和碳水化合物对斜带石斑鱼的互作效应,实验采用3×3因子设计,配制蛋白质水平(P)为38%、45%和52%,淀粉水平(S)为10%、20%和30%的9种实验饲料,分别饲喂斜带石斑鱼56 d。结果显示,38%粗蛋白与10%淀粉饲料组(38P/10S饲料组)增重率显著低于其他各组,52P/10S组增重率最高,但与45P/20S、45P/30S、52P/20S组差异不显著。增加饲料蛋白质或淀粉水平显著增加饲料效率、鱼体蛋白质与脂肪含量及肝糖原肝脂含量,而降低摄食率和鱼体水分含量。增加饲料蛋白质水平降低蛋白质效率,但增加淀粉水平却增加蛋白质效率及肝体比与脏体比。饲料蛋白质水平和淀粉水平对鱼体灰分含量无明显影响。肝中肝酯酶、脂蛋白酯酶、脂肪酸合成酶、谷丙转氨酶和谷草转氨酶活性均随蛋白质或淀粉水平的升高呈显著上升趋势。增加饲料蛋白质水平显著降低肝中葡萄糖-6-磷酸酶活性,而增加肝中苹果酸酶活性,但对肝中葡萄糖激酶、丙酮酸激酶、磷酸果糖激酶、磷酸烯醇式丙酮酸羧激酶和葡萄糖-6-磷酸脱氢酶活性没有明显影响。增加饲料淀粉水平显著增加肝中葡萄糖激酶、丙酮酸激酶、磷酸果糖激酶、葡萄糖-6-磷酸脱氢酶和苹果酸酶活性,但显著降低磷酸烯醇式丙酮酸羧激酶和葡萄糖-6-磷酸酶活性。上述结果显示,斜带石斑鱼的生长和肝脏代谢明显受饲料蛋白质和淀粉水平的影响,其中,糖代谢酶活性受淀粉水平的影响较大,而受饲料蛋白质水平的影响较小,斜带石斑鱼生长适宜的饲料蛋白质和淀粉水平分别为45%和20%。  相似文献   

16.
The effect of dietary amylose/amylopectin (AM/AP) ratio on growth, feed utilization, digestive enzyme activities, plasma parameters, and postprandial blood glucose responses was evaluated in juvenile obscure puffer, Takifugu obscurus. Five isonitrogenous (430 g kg?1 crude protein) and isolipidic (90 g kg?1 crude lipid) diets containing an equal starch level (250 g kg?1 starch) with different AM/AP ratio diets of 0/25, 3/22, 6/19, 9/16 and 12/13 were formulated. Each experimental diet was fed to triplicate groups (25 fish per tank), twice daily during a period of 60 days. After the growth trial, a postprandial blood response test was carried out. Fish fed diet 6/19 showed best growth, feed efficiency and protein efficiency ratio. Hepatosomatic index, plasma total cholesterol concentration, liver glycogen and lipid content, and gluconokinase, pyruvate kinase and fructose-1,6-bisphosphatase activities were lower in fish fed highest AM/AP diet (12/13) than in fish fed the low-amylose diets. Activities of liver and intestinal trypsin in fish fed diet 3/22 and diet 6/19 were higher than in fish fed diet 9/16 and diet 12/13. Activities of liver and intestinal amylase and intestinal lipase, and starch digestibility were negatively correlated with dietary AM/AP ratio. Fish fed diet 3/22 and diet 6/19 showed higher plasma total amino acid concentration than fish fed the other diets, while plasma urea nitrogen concentration and activities of alanine aminotransferase and aspartate aminotransferase showed the opposite trend. Equal values were found for viscerosomatic index and condition factor, whole body and muscle composition, plasma high-density and low-density lipoprotein cholesterol concentrations, and activities of lipase and hexokinase and glucose-6-phosphatase in liver. Postprandial plasma glucose and triglyceride peak value of fish fed diet 12/13 were lower than in fish fed the low-amylose diets, and the peak time of plasma glucose was later than in fish fed the other diets. Plasma glucose and triglyceride concentrations showed a significant difference at 2 and 4 h after a meal and varied between dietary treatments. According to regression analysis of weight gain against dietary AM/AP ratio, the optimum dietary AM/AP ratio for maximum growth of obscure puffer was 0.25. The present result indicates that dietary AM/AP ratio could affect growth performance and feed utilization, some plasma parameters, digestive enzyme as well as hepatic glucose metabolic enzyme activities in juvenile obscure puffer.  相似文献   

17.
A 60-day experiment was conducted to study the effect of dietary gelatinized (G) and non-gelatinized (NG) starch on the key metabolic enzymes of glycolysis (hexokinase, glucokinase, pyruvate kinase, and lactate dehydrogenase), gluconeogenesis (glucose-6 phosphatase and fructose-1,6 bisphosphatase), protein metabolism (aspartate amino transferase and alanine amino transferase), and TCA cycle (malate dehydrogenase) in Labeo rohita juveniles. In the analysis, 234 juveniles (2.53 ± 0.04 g) were randomly distributed into six treatment groups each with three replicates. Six semi-purified diets containing NG and G cornstarch, each at six levels of inclusion (0, 20, 40, 60, 80, and 100) were prepared viz., T1 (100% NG, 0% G starch), T2 (80% NG, 20% G starch), T3 (60% NG, 40% G starch), T4 (40% NG, 60% G starch), T5 (20% NG, 80% G starch), and T6 (0% NG, 100% G starch). Dietary G:NG starch ratio had a significant (P < 0.05) effect on the glycolytic enzymes, the highest activities were observed in the T6 group and lowest in the T1 group. On the contrary, the gluconeogenic enzymes, the glucose-6-phosphatase and fructose-1,6 bisphosphatase activities in the organs, liver and kidney were recorded highest in the T1 group and lowest in the T6 group. The liver aspartate amino transferase activity showed an increasing trend with the decrease in the dietary G level. However, the muscle aspartate amino transferase activity was not significantly (P > 0.05) influenced by the type of dietary starch. The alanine amino transferase activity in both liver and muscle showed an increasing trend with the decrease in the dietary G level. The liver and muscle malate dehydrogenase activities were lowest in the T6 group and highest in the T1 group. Results suggest that NG (100%) starch diet significantly induced more the enzyme activities of amino acid metabolism, gluconeogenesis, and TCA cycle, whereas partial or total replacement of raw starch by gelatinized starch increased the glycolytic enzyme activity.  相似文献   

18.
In the present study, three different copper (Cu) concentrations (control, 10 and 100 μM, respectively) and three incubation times (24, 48 and 96 h) were chosen to assess in vitro effect of Cu on lipid metabolism in hepatocytes of grass carp Ctenopharyngodon idellus. Increased glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and carnitine palmitoyltransferase I activities were observed in hepatocytes with increasing Cu concentration and exposure duration. Cu decreased mRNA levels of several lipogenic and lipolytic genes at 24 h. However, at 48 h, Cu down-regulated the process of lipogenesis but up-regulated that of lipolysis. The Cu-driven up-regulation of lipolytic genes was maintained after 96 h and accompanied by a decreased intracellular triglyceride accumulation, while no effect on lipogenic genes was shown. Thus, 96-h Cu exposure induced lipid depletion, possibly due to the up-regulation of lipolysis. Although in this process, lipogenesis might be up-regulated, it was not enough to compensate lipid consumption. Our study represents the first approach to concentration- and time-dependent in vitro effects of Cu on lipid metabolism of fish hepatocytes and provides new insights into Cu toxicity in fish at both enzymatic and molecular levels.  相似文献   

19.
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20.
设置持续投喂组(C,持续投喂8周)、饥饿再投喂组(R,饥饿4周+再投喂4周)和持续饥饿组(S,饥饿8周)3个处理组,研究3种不同饥饿处理对草鱼(Ctenopharyngodon idellus)血清生化指标、糖原和糖代谢相关酶和葡萄糖转运蛋白1(GLUT1)的影响,同时在此实验基础上研究草鱼在急性高糖负荷胁迫下的糖耐受能力、糖代谢相关酶和GLUT1的变化规律,旨在阐明草鱼在饥饿及再投喂处理条件下的糖代谢特征。选取初重为(125.35±0.54)g的草鱼,饲养8周后以30 mg/100 g体重的剂量腹腔注射葡萄糖研究其糖耐受能力。结果显示,S组肝糖原和血清的血糖、甘油三酯含量均最低。饥饿处理对草鱼糖耐受能力影响显著,S组血糖含量在各时间点上显著低于其余两组(P0.05),肝糖原在6 h达到峰值;饥饿处理对草鱼肝脏糖代谢关键酶影响显著,饥饿处理(S组)诱使磷酸烯醇式丙酮酸激酶(PEPCK)活性上升但抑制丙酮酸激酶(PK)和果糖-6-磷酸激酶(PFK)的活性(P0.05),而饥饿再投喂(R组)后PEPCK、PK和PFK酶活性恢复到持续投喂(C组)处理水平。注射葡萄糖后S组肝脏GK酶活性增幅最大,PK酶活性呈上升趋势,而R组则呈先下降后上升的趋势;饥饿处理对草鱼肝脏和肌肉GLUT1表达影响显著,注射葡萄糖后,除R组肝脏组织外,其余各组草鱼肝脏和肌肉组织GLUT1表达量均呈先上升后下降的趋势,且S组肌肉GLUT1表达量在各个时间点上均高于其余两组(P0.05)。研究结果表明,在不同饥饿处理下,草鱼可通过消耗肝糖原和甘油三酯及降低肝脏糖酵解相关酶(PK和PFK)活性和促进糖异生PEPCK酶活性来应对饥饿胁迫,而饥饿处理可诱使GK和PK酶活性上升、促进糖原合成和激活GLUT1基因的表达和转运来缓解草鱼急性高糖负荷,从而提高其糖耐受能力。  相似文献   

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