| This study investigated the effects of different salinity stress on enzyme activity and gene expression of glycometabolism related enzymes in Boleophthalmus pectinirostris,and analyzed the regulation effect of exogenous glucose and metformin on glycometabolism of Boleophthalmus pectinirostris under high salinity stress.The research results can provide the necessary reference for the development of fish artificial full-priced compound feed.(1)The effect of acute salinity stress on the metabolism of Boleophthalmus pectinirostris.A total of 3 salinity treatment groups were set up in the experiment: low salinity group(0‰),normal salinity group(17‰,control group),and high salinity group(30‰).The stress experiment lasted for 5 days.The results showed that the content of glycogen in fish liver decreased significantly in the low salinity group,and the activity of glucokinase(GK),pyruvate kinase(PK)and phosphofructokinase(PFK)in the low salinity group was the highest,followed by the high salinity group.The activity of experimental fish was the lowest in the control group;the activity of phosphoenolpyruvate kinase(PEPCK)and glucose-6-phosphatase(G6Pase)in experimental fish was significantly higher in the high and low salinity groups than in the control group;The expression level of m RNA was significantly higher than that of the low salinity group.The expression level of FBPase gene in the control group was the lowest,and the expression level of PFK gene m RNA in the low salinity group was significantly higher than that in the control group.The fish with high salinity had the lowest expression of PFK gene.The results showed that the salinity stress accelerated the decomposition of liver glycogen in the Boleophthalmus pectinirostris,and the Boleophthalmus pectinirostris provided energy to the body by increasing the metabolic activity of glucose.(2)Differences in glucose metabolism between the liver and gill of Boleophthalmus pectinirostris under acute salinity stress.A total of 2 salinity treatment groups were set up in the experiment: normal salinity group(17 ‰,control group)and high salinity group(30 ‰),stress test for 24 h.The results showed that the contents of glycogen and glycogen in the high salinity group reached the lowest levels at 24 h and 3 h,respectively,which were significantly lower than those in the control group;the PK and GP enzyme activities of the fish liver in the high salinity group were first After the increase,the decrease trendwas highest at 3 h,which was significantly higher than that of the control group.The PK and GP enzyme activities of the experimental fish larvae in the high salinity group first increased and then decreased,reaching the maximum at 1 h and 6 h respectively.,significantly higher than the control group;high salinity group experimental fish liver GS and GP gene m RNA expression was first increased and then decreased,and reached the highest at 3 h and 1 h,significantly higher than the control group;high salinity group the m RNA expression levels of GS,GP,and NKA in the experimental fish carp increased first and then decreased,and reached the highest at 3 h,1 h,and 12 h,respectively,which was significantly higher than that of the control group.The results showed that Boleophthalmus pectinirostris gill tissues can provide energy to the body by decomposing glycogen under acute salinity stress.(3)The effect of glucose on the glucose metabolism of the Boleophthalmus pectinirostris under acute salinity stress.A total of 2 salinity treatment groups were set up in the experiment: normal salinity group(17 ‰,control group)and high salinity group(30 ‰),and the dose of intraperitoneal injection of glucose was 30 mg/100 g.The stress experiment lasted for 12 h.The results showed that the liver glycogen content in the control group first increased and then decreased,and reached the highest value at 1 h.However,the high salinity group experimental fish liver glycogen had no significant difference during the whole experiment period;the control group experimental fish GK The activity of PK enzyme increased at first and then decreased,and reached the highest at 3 h and 1 h respectively.The activity of GK,PK and PFK in the high salinity fish group first increased and then decreased,and reached the peak at 1 h.The enzyme activity of PEPCK in the experimental fish showed a decreasing trend,and the activity of PEPCK and FBPase in the high salinity fish increased first,then decreased and then increased.The lowest value of PFK gene m RNA expression in experimental group was higher than 6 h in high salinity group.The experimental fish PFK was found in high salinity group and control group.The lowest m RNA expression of FBPase gene appeared at 3 h.The results showed that exogenously supplemented glucose can improve the glycolysis of the liver of the Boleophthalmus pectinirostris under high salinity stress and weaken the effect of gluconeogenesis.(4)The effect of metformin on the glucose metabolism in the Boleophthalmus pectinirostris under acute salinity stress.A total of two treatment groups were set up in the experiment: the high salinity group(30 ‰)and metformin group(30 ‰,10 μM).The stresstest lasted for 24 h.The results showed that the m RNA expression levels of GK in the experimental fish liver in the high salinity group and metformin group first increased and then decreased.At 6-24 h,the experimental fish in the metformin group was significantly higher than the high salinity group;the high salinity group and metformin.The m RNA expression levels of G6 Pase in the experimental fishes first increased and then decreased.At 6-24 h,the metformin group was significantly lower than the high salinity group;the m RNA expression levels of PEPCK in the experimental fish with high salinity and metformin increased gradually.The metformin group was significantly lower than the high salinity group.The results showed that metformin could improve the glycolysis of liver in the Boleophthalmus pectinirostris under high salinity stress and reduce the effect of gluconeogenesis.It can effectively promote the utilization of carbohydrates in Boleophthalmus pectinirostris. |
