| In this paper,histological and biochemical methods were used to investigate the changes of blood biochemical indices and histological structure in grass carp with diseased liver.Further,nutritional toxicology studies were conducted to investigate the effects of different dietary rapeseed meal(RM) levels(0,16%,32%,48%and 64%)on growth,feed utilization,blood biochemical indices,fish body composition,lipid and glycogen levels in hepatopancreas and liver pathology of the grass carp.In addition,the effects of AITC on the toxicity of primordial cultured liver cells of grass carp were studied to reveal the mechanism of toxicity of rapeseed meal acting on fish.The results were as follows:1.In contrasted to fish with normal liver,the hepatopancreas in fish with abnormal liver showed pale,even green color;the hepatic cells in fish with abnormal liver showed fatty vacuole and necrosis to some extent;Serum activities of ALT,AST and the contents of direct bilirubin,total bilirubin,triglycerides,creatinine in fish with abnormal liver increased significantly(P＜0.05).Serum concentrations of urea nitrogen and cholesterol showed increasing trends but not significantly(P＞0.05).However, serum concentration of glucose and ALP in fish with abnormal liver showed no significant change(P＞0.05).Serum activity of SOD decreased significantly(P＜0.05), and alexin C3,C4 showed decreasing trends but not significantly(P＞0.05).Liver glycogen in fish with abnormal liver decreased significantly(P＜0.05),however,the liver lipid levels showed an increasing trend but not significantly(P＞0.05).2.Different dietary rapeseed meal(RM) levels showed significant effect on the growth performance of grass carp.The highest weight gain rate was observed in the control group;and the weight gain rate decreased significantly(P＜0.05) as the rapeseed meal level increased from 32%to 64%.Feeding rate(FR) showed no significant difference in the first four groups(P＞0.05),however,FR in 64%RM group was significantly lower than the other groups.The highest feed conversion efficiency was observed in 16%RM group and the lowest in 32%RM group,but no significant difference was observed among groups(P＞0.05);the specific growth rate(SGR) was depressed significantly(P＜0.05) by the increasing of RM level,and the highest SGR was observed in the control group.Protein efficiency was the highest in the 16%RM group and those of the 48%RM group and 64%RM group were significantly lower than the other groups(P＜0.05).Body crude protein,crude ash and moisture among all groups showed no significant difference(P＞0.05);However,crude fat of 16%and 32% RM group were significantly higher than the other groups(P＜0.05),no other significant difference in body fat was observed(P＞0.05).Serum cholesterol and triglycerides contents showed increasing trend as dietary rapeseed meal level increased(P＞0.05),so did aspartate transaminases(AST) and alanine transaminases(ALT).Serum glucose(GLU),total protein(TP) and total bilirubin(TB) showed no significant difference among all groups(P＞0.05).When in the feed,the concentration of serum urea nitrogen(BUN) increased significantly (P＜0.05) as dietary rapeseed meal content reached 32%.The 48%group had the highest liver glycogen content,while 32%group the lowest(P＜0.05),no significant difference was observed among 16%RM group,48%RM group and the control group (P＞0.05).Liver lipid contents in the tested groups were significantly higher than the control group(P＜0.05),and the highest was in 64%RM group,then in 32%RM group. There were no significant difference between group 64%and group 32%either for glycogen and lipid aggradations(P＞0.05).Metamorphic cells with vacuole were observed in 16%RM group.In 32%RM group,except metamorphic cells with vacuole, nucleolus excursion in part cells was also observed.As the RM level increased,the number of metamorphic cell with vacuole increased,liver lipid deposition accelerated and the function of liver was seriously damaged.3.There were some effects of allyl isothiocyanate(AITC) on primary cultured liver cells of grass carp.Cells grew well and only some dead cells were observed in control group without administration.Compared to the control,cells in 10-5 and 10-6 mol/L AITC groups showed no significant difference and also grew well.In 10-3 and 10-4 mol/L AITC groups,there exited some live sticking cells,part of them began to fall off,accompanied with nucleolus excursion,and no live cells were found in the high concentration group of 10-2 mol/L,nearly all the cells were suspended in culture medium.The lowest determined values of AST and ALT were observed in 10-2 mol/L AITC group,significantly lower than the control group and other groups(P＜0.05).The activities of AST among other groups showed no significant difference the(P＞0.05). ALT activity values of 10-3 mol/L group and group 10-4 mol/L were significantly higher than that of the control group and group 10-2mol/L,while ALT activity values of 10-5 mol/L and 10-6 mol/L group showed no significant difference(P＞0.05),compared with the control group.The highest determined value of LDH was in 10-2mol/L group,then in 10-3mol/L group.Other groups showed no significant difference with the control group(P＞0.05).The content of MDA increased significantly with the increase of the concentration of AITC(P＜0.05).
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