运输应激对刀鲚生理生化指标和HPI轴基因表达影响及甘草甜素的作用

Effect of transport stress on physiological-biochemical indices and expression of HPI genes and roles of glycyrrhizin on transport response in Coilia nasus

以刀鲚(Coilia nasus)为研究对象,运用荧光定量和相关生化测定方法,研究运输应激对下丘脑-垂体-肾间组织轴(HPI)基因表达和肝脏氧化指标的影响;同时采用浸泡的方式研究甘草甜素(glycyrrhizin,GL)对以上指标的调控作用。结果显示:运输后,脑中促肾上腺皮质激素释放激素(CRH)基因、阿黑皮素原(POMC)基因和硬骨鱼紧张肽(UI)基因的表达水平显著降低;头肾中皮质醇受体(GR)基因的表达水平运输2 h明显下降,4 h时表达水平最低,8 h显著升高。运输应激可以明显降低肝脏过氧化氢酶(CAT)的活性,显著提高肝脏丙二醛(MDA)的水平,而对谷胱甘肽过氧化物酶(GSH-PX)和脂质过氧化物(LPO)无显著影响。添加甘草甜素6 h后头肾GR基因的表达水平降低,脑中CRH和POMC基因的表达水平显著升高,但是脑中UI基因的表达水平无明显变化。此外,添加甘草甜素对肝脏CAT、MDA、GSH-PX和LPO无显著影响。以上结果表明,运输应激调控HPI轴的基因表达发生了不同程度的变化,而且降低了机体的抗氧化能力,使刀鲚处于氧化应激状态中。GL也可以影响HPI轴的基因表达,但不能有效缓解刀鲚的运输应激引发的氧化应激。

In this study, we selected Coilia nasus as the research object, and we studied the effect of transport response on mRNA level of hypothalamus-pituitary-interrenal axis （HPI） genes and liver oxidative indices, using qRT-PCR and biochemistry method. Meanwhile, Coilia nasus were soaked with a certain concentration of glycyrrhizin （GL） to investigate the regulation of the above indices during transportation. The results showed that corticotropin releasing hormone （CRH） mRNA, proopiomelanocortin （POMC） mRNA and urotensin I （UI） mRNA expression in brain were significantly suppressed after transportation. Glucocorticoid receptor （GR） mRNA expression in head kidney decreased significantly at 2 h and reached the minimum at 4 h, then increased obviously at 8h. After transportation, Catalase （CAT） activities in liver decreased significantly, the level of malonaldehyde （MDA） in liver rose dramatically, glutathione peroxidase （GSH- PX） activities and the lipid peroxide （LPO） content of liver had no significant change. After 6 h, glycyrrhizin suppressed distinctly the level of GR mRNA in head kidney, and inversely stimulated CRH mRNA and POMC mRNA expression of brain with significant difference, but UI mRNA expression in brain had no obvious change. Moreover, glycyrrhizin had no significant effect on the activities of CAT and GSH-PX and the content of MDA and LPO. All the results above indicated that levels of HPI genes expression were changed to different extent after transportation. Transport response reduced hepatic anti-oxidative capacity and caused oxidative stress in Coilia nasus. Likewise, glycyrrhizin can regulate the expression of HPI genes, but it can＇t effectively relieve oxidative stress caused by transport stress