急性温度胁迫对虹鳟肝脏代谢酶活性及生长相关基因表达的影响

Effects of acute temperature stress on metabolic enzyme activity and gene expression related to growth in rainbow trout Oncorhynchus mykiss

为探究急性温度胁迫对虹鳟Oncorhynchus mykiss肝脏代谢酶和部分生长调控基因表达的影响,采用血清生化分析仪测定了低温(6℃)和高温(24℃)胁迫下虹鳟(体质量为240 g±18 g)血清中谷草转氨酶(AST)、谷丙转氨酶(ALT)和碱性磷酸酶(ALP)的活性,通过放射免疫法测定了血清类胰岛素生长因子1(IGF-1)的含量,采用实时定量法测定了肝脏中GHR1、IGF-1和IGF-2的表达量。结果表明:温度胁迫2 h后,低温和高温两个处理组鱼的AST活性和高温组的ALT活性均呈先升高后降低的趋势,均在恢复6 h时达到最大值,而低温组鱼的ALT活性在胁迫后恢复0 h时就显著升高(P<0.05),随后逐渐降低至对照组水平;低温组鱼的ALP活性在胁迫后显著降低(P<0.05),并在48 h的恢复期间始终维持在较低水平,而高温组鱼的ALP活性比对照组略有降低(P>0.05);低温组鱼的血清IGF-1激素含量在恢复12 h后呈上升趋势,并在48 h时恢复至对照组水平,而高温组血清IGF-1含量在胁迫后始终处于较低水平;两个处理组肝脏中,GHR1基因表达量比对照组略有降低(P>0.05),而IGF-1和IGF-2基因表达量均呈先降低后升高的趋势,且IGF-2表达量下降更明显,并在恢复12 h时达到最低值。研究表明:温度胁迫后,虹鳟血清转氨酶活性降低,肝脏受到损伤;血清IGF-1激素含量下降,肝脏中GHR1、IGF-1和IGF-2基因表达量均低于对照组;高温组各指标变化较大,说明属于冷水鱼类的虹鳟受高温影响更为显著。

Activities of serum aspartate aminotransferase（ AST）,alanine aminotransferase（ ALT） and alkaline phosphatase（ ALP） were determined in rainbow trout Oncorhynchus mykiss with body weight of（ 240 g ± 18 g） exposed to low（ 6 ℃） and high temperature（ 24 ℃） by a BS-180 biochemical analyzer,and levels of serum insulinlike growth factor-1（ IGF-1） and the expression of GHR1,IGF-1 and IGF-2 in liver were detected by radioimmunoassay and by real-time quantification. The activities of serum AST and ALT were shown to be increased first and then decreased,the maximum at 6 h and significantly higher in the lower temperature group for ALT even at 0 h（ P〈0. 05）,finally being reduced to the level in the control group. The ALP activity was significantly decreased at 0 h（ P〈0. 05）,and then maintained low level in low temperature group,while the ALP activity was decreased slightly in high temperature group. The serum IGF-1 level was found increase at 0 h and then recovery to the level in the control group at low temperature exposure. In the high temperature exposure,however,the serum IGF-1 level was kept at low level,without significant difference（ P〉0. 05）. The expression of IGF-1 and IGF-2 genes was shown to be decreased firstly and then increased,the minimum at 12 h,significantly lower for IGF-2 gene. The findings revealed that acute temperature led to harmful liver and to increase in AST and ALT activities and to decrease in ALP activity; meanwhile serum IGF-1 level and the expression of GHR1,IGF-1 and IGF-2 also were decreased,indicating that acute temperature may affect the expression of growth related genes.