盐度对花鲈幼鱼消化酶和抗氧化系统的影响

Effects of Salinity on Digestive Enzymes and Antioxidant System of Juvenile Lateolabrax maculatus

为探讨不同盐度对花鲈(Lateolabrax maculatus)幼鱼消化酶活性和抗氧化水平的影响,经过30 d养殖,应用试剂盒检测了盐度0、10、20、30条件下胃、幽门盲囊及肠道中胃蛋白酶、α-淀粉酶、脂肪酶活力,肝和肌肉组织中超氧化物歧化酶、过氧化氢酶的活力以及总抗氧化能力和丙二醛含量。结果显示,胃蛋白酶活力在0盐度组最高,4个盐度组间具有显著性差异(P < 0.05);同一盐度组,胃蛋白酶活性在胃组织中高于幽门盲囊和肠道。随着盐度的增加,胃组织的α-淀粉酶活力呈逐渐降低趋势,幽门盲囊和肠道的α-淀粉酶活力则逐渐升高。胃组织中,0盐度组脂肪酶有较高活性,10盐度组脂肪酶活性最低,20和30盐度组酶活性逐渐升高,并在30盐度组达最大值,4个盐度组之间差异显著(P < 0.05);幽门盲囊中,脂肪酶活力随盐度的增加,呈现先升高后降低趋势;肠组织中,0盐度和10盐度组脂肪酶酶活力差异不显著(P > 0.05),20盐度和30盐度组增加显著(P < 0.05)。肝组织超氧化物歧化酶和过氧化氢酶在0盐度组活性最高,随盐度变化,呈现相似的变化趋势;肌肉中超氧化物歧化酶和过氧化氢酶活性整体上随盐度增高有上升趋势。0盐度组和30盐度组肝组织丙二醛含量和总抗氧化能力观测值都较高。在肌肉中,丙二醛含量在10盐度组达到较高值,随后盐度增加丙二醛含量变化不显著(P > 0.05);总抗氧化能力含量也在10盐度组时达到最高值,其余组均下降。本研究认为,花鲈幼鱼不同消化酶活性所需的盐度条件各有差异,同时抗氧化系统能够响应不同的盐度条件。

To investigate the effects of salinity on digestive ability and antioxidant capacity in juvenile Lateolabrax maculatus, four salinity levels (0, 10, 20, 30) were set in this study. After 30 days’ culture, tissue samples were collected and preserved in liquid nitrogen for later use. According to the manufacturer’s instructions, the activities of pepsin (PPS), amylase (AMS), lipase (LPS), superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) and malondialdehyde (MDA) content were measured using kit analysis. The results showed that the PPS activity was higher at salinity 0 than at higher salinities, and there were significant differences among different salinity groups. In the same salinity group, the enzyme activity of peptic cathepsin was higher than that of pyloric caecum and intestinal tract (Fig. 1). With the increase of salinity, the activity of AMS in gastric tissue decreased gradually, while the activity of AMS in pyloric caecum and intestinal tract increased gradually (Fig. 2). In gastric tissues, LPS at salinity 0 had a high activity, LPS at salinity 10 had the lowest activity, enzyme activity increased at salinity 20 and salinity 30 gradually, reaching the maximum at salinity 30, and there was significant difference among groups (P < 0.05);in pyloric caecum, the activity of LPS increased firstly and then decreased with the increase of salinity;in intestinal tissue, there was no significant difference in LPS activity between salinity 0 and salinity 10 group (P > 0.05), and then gradually increased (Fig.3). The highest activities of SOD and CAT in liver were found in group salinity 0 and the other three groups showed similar values (Fig. 4);the activities of SOD and CAT in muscle increased with salinity increase as a whole (Fig. 5). MDA and T-AOC were higher in liver at salinity 30 and 0 (Fig. 6), while in muscle, MDA content reached a higher value at salinity 10 and then increased with higher salinities (P < 0.05), but the difference was not significant (P > 0.05);T-AOC content also reached the highest value at salinity 10 and decreased in other groups (Fig. 7). The results show that different digestive enzymes need different salinity conditions for their proper functiopns in juvenile L. maculatus, and that the changes of salinity may induce the response of antioxidant system.