Effects Of Pyridoxine On The Mechanism Of Antioxidative In Jian Carp (Cyprinus Carpio Var. Jian), And Pathology Of The Pyridoxine Deficiency Syndrome In Juvenile Jian Carp

This experiment was conducted to study the effects of dietary pyridoxine(PN) levels on antioxidant status of juvenile Jian carp(Cyprinus carpio var.Jian) and determine the histopathology observation and effect of digestive enzyme and immune function with dietary pyridoxine deficiency.Semi-purified diets with seven levels(0.20,1.71,3.23,4.96, 6.32,8.58 and 12.39 mg PN/kg) of supplemental calcium d-pantothenate were fed for 80 days to triplicate groups of 50 fish(initial weight 11.70±0.05 g,mean±SD).The effect of pyridoxine on antioxidant status in fish showed that:pyridoxine significantly decreased malondialdehyde(MDA) in serum,intestine and kidney tissue.The MDA content was reduced with increasing dietary pyridoxine levels up to 3.23,4.96 and 3.23mg kg^-1 diet(P＜0.01 or P＜0.05),respectively,in serum and intestine tissue,and no differences were found with further increase of pyridoxine levels(P＞0.05).In serum, intestine and kidney tissue path-analysis results indicated levels of pyridoxine had significantly negative direct effects on MDA content(P_10.1=-0.287,d_10.1=0.0824;P_20.1= -0.455,d_20.1=0.208;P_30.1=-0.885,d_30.1=0.784).Pyridoxine significantly decreased protein carbonyl in serum,intestine and kidney tissue(P＜0.01).Regression analysis results indicated that protein carbonyl content was lowest when pyridoxine concentration≥5.91 and 6.27 mg kg^-1,respectively,in intestine and kidney tissues.Path-analysis results indicated that levels of pyridoxine had negative direct effects on protein carbonyl content, in intestine and kidney tissue(P_10.1=1.702,d_10.1=2.896;P_20.1=-0.259,d_20.1=0.0670). This result suggested that pyridoxine may decrease lipid peroxidation and oxidative damage to proteins in fish.Pyridoxine significantly increased anti-superoxide anion activity(ASA) in serum,intestine and kidney tissue.The ASA was increased with increasing dietary pyridoxine levels all up to 3.23mg kg^-1 diet(P＜0.01 or P＜0.05), respectively,in serum and intestine tissue,and no differences were found with further increase of pyridoxine levels(P＞0.05).The correlation-analysis results indicated that there were significant negative correlation between MDA with ASA in serum,intestine and kidney tissue(r₁=-0.924,P＜0.01;r₂=-0.943,P＜0.01;r₃ =-0.825,P＜0.05),and protein carbonyl was negative related to ASA in intestine tissue(r=-0.964,P＜0.01). Path-analysis results indicated that ASA had negative direct effect on MDA content,in serum,in intestine and kidney tissue(P_10.4=-0.327,d_10.4=0.107;P_20.4=-0.389,d_20.4= 0.151;P_30.4=-1.127,d_30.4=1.271).These results indicated that pyridoxine may enhance ASA and increased antioxidative defense in fish.Pyridoxine significantly increased anti-hydroxyl radical activity(AHR) in kidney tissue.The AHR was increased with increasing dietary pyridoxine levels all up to 4.96 mg kg^-1 diet(P＜0.01),in kidney tissue, and no differences were found with further increase of pyridoxine levels(P＞0.05).The correlation-analysis results indicated that protein carbonyl was negative related to AHR in kidney tissue(r=-0.981,P＜0.01).Pyridoxine had no effect on AHR in serum and intestine.Pyridoxine significantly increased the activities of superoxide dismutase(SOD), catalase(CAT),glutathione peroxidase(GSH-Px),glutathione S-transferase(GST) and glutathione reductase(GR) in serum.The activities of SOD,CAT,GSH-Px,GST and GR in serum,were increased with increasing dietary pyridoxine levels all up to 4.96,3.23,3.23,3.23 and 6.32 mg kg^-1 diet(P＜0.01 or P＜0.05),respectively,and no differences were found with further increase of pyridoxine levels(P＞0.05).The correlation-analysis results indicated that there were significantly negative correlation between MDA with the activities of SOD,CAT,GSH-Px,GST and GR in serum(r₁=-0.924,P＜0.01;r₂=-0.817, P＜0.05;r₃=-0.968,P＜0.01;r₄=-0.926,P＜0.01;r₅=-0.913,P＜0.05;r₆=-0.824,P＜0.05;r₇=-0.907,P＜0.05),and there were significantly negative correlation between protein carbonyl and antioxidant enzymes in intestine and kidney tissue(P_10.2=-1.575, d_10.2=2.4819;P_10.3=-0.705,d_10.3=0.4966;P_10.4=-3.402,d_10.4=11.576;P_20.2=-0.159, d_20.2=0.0252;P_20.3=-0.970,d_20.3=0.0252;P_20.4=-0.327,d_20.4=0.107).The effect of pyridoxine on the activites of antioxidative enzymes in intestine and kidney have similar pattern with serum.These results indicated that pyridoxine may enhance the activites of SOD,CAT,GSH-Px,GST and GR,thus increased antioxidative defense systemes in fish. Pyridoxine significantly increased reduced glutathione(GSH) in serum,intestine and kidney tissue(P＜0.01).Regression analysis results indicated that pyridoxine concentration≥4.78,4.77 and 5.41 mg kg^-1,respectively,in serum,intestine and kidney tissues could achieve the requirement of GSH.Correlation-analysis results indicated that there was significant negative correlation between MDA with the GSH content in serum in serum(r₁=-0.907,P＜0.05;).In intestine and kidney tissue,correlation-analysis results indicated that levels of GSH were negative correlated with MDA and protein carbonyl contents in intestine and kidney tissue(r₁₁=-0.861,P＜0.05;r₁₂=-0.865,P＜0.05;r₂₁= -0.930,P＜0.01;r₂₂=-0.943,P＜0.01).These results suggested that pyridoxine may increase GSH content,and promoted non-enzymes antioxidative ability in fish.Results indicated that the diet which pyridoxine deficient results in the increased mortality,tetany,convulsions,epiletiform fits and other nervous disorders;exophthalmus, hemorrhage of fins,dissipated in the skin of head and hyperplasia of gill filaments,etc.. Clinic anatomises showed that tumescence or atrophy in the head kidney,definite kidney, spleen,hepatopancreas and gallbladder of fish fed diet lack of pyridoxine.Reduced vacuolization,cytolysis in hepatocytes;deposited siderous heme of head kidney; degeneration of proximal tubules in kidney;decreased lymphoid cells of spleen;intestinal villus were ruptured and degeneration of myocardial fiber in this experiment.In considering these results,pyridoxine can decrease lipid peroxidation and oxidative damage to proteins in Jian carp.Pyridoxine promoted fish antioxidant capacity by removing superoxide anion and lipid peroxidative product in organism,intestine and kidney.Pyridoxine also decreased the ability of kidney to produce hydroxy radical.The optimum dietary pyridoxine requirement for the levels of malondialdehyde(MDA) in serum,intestine and kidney tissue of juvenile Jian carp(11～75 g) was determined to be 3.48,4.72 and 3.44 mg/kg,respectively,and the optimum dietary pyridoxine requirement for the protein carbonyls in intestine and kidney tissue of juvenile Jian carp(11～75 g) was determined to be 5.91 and 6.27 mg/kg,respectively.Fish fed pyridoxine-deficient diets performed increased mortality,tetany,convulsions,epiletiform fits and other nervous disorders;exophthalmus,hemorrhage of fins,dissipated in the skin of head and hyperplasia of gill filaments,etc..The pathologic changes of tissue and cell trauma such as hepatopancreas,head kidney,kidney,spleen,intestinal and fiber were observed.