应激大鼠脾脏内诱导型一氧化氮合酶活性变化及其意义

在捕食压力下,大鼠脾脏诱导型一氧化氮合酶(iNOS)明显表达,说明iNOS起到了重要的生理功能,然而,NOS的表达及在亚细胞水平的定位以及相应的差异变化等都很不明确,本试验采用捕食应激模型,利用免疫组织化学方法和生化测定,检测心理性应激对大鼠脾脏iNOS活性的影响及探讨这种影响与应激动物免疫力下降之间的关系.结果表明iNOS免疫阳性细胞表达部位集中于脾脏的红髓和边缘区,白髓中几乎没有.与对照组相比,在应激1~12d的过程中,应激组大鼠脾脏内iNOS的活性逐渐升高,至d12最为显著(P<0.01).但在后期应激13~30d,脾内iNOS的表达又逐渐减少.生化测定结果表明,NOS和NO的含量变化与iNOS的活性变化相似,在心理性应激早中期较高,至d12最为显著(P<0.01),而到中后期则逐渐降低.结果提示,iNOS活性程度与动物心理应激程度密切相关;应激过程中大鼠脾脏内由于iNOS的活性增加导致产生过量的NO,这可能与应激导致大鼠免疫力下降有关.图1表2参10

CHANGES IN INOS ACTIVITY IN SPLEEN OF RAT DURING ITS PSYCHOLOGICAL STRESS

The inducible nitric oxide synthase (iNOS) is obviously expressed in speen of rats under the predator stress, suggesting important function for iNOS in speen physiology. However, the expression and subcellular localization for NOS in speen development and differentiation are largely unknown. In the present study, the changes in iNOS activity in spleen of rats under predator stress were studied to explore the role of iNOS in the decreased immunoactivity of the stressed rats. The changes in iNOS were observed with immunobistochemical method, and the contents of NOS and NO in spleen with biochemical method. iNOS positive cells appeared in red pulp and marginal zone of rat spleen, but almost none in white pulp. iNOS activity was stable in rat spleen in the control group without stress, but significantly different in stressed group. From day 1 to day 12 under stress, the activity of iNOS was increased, and on day 12 it was increased obviously (P<0.01). From day 13, iNOS activity in spleen began to decrease gradually and on day 30 the decrease was obvious. The changes in contents of NOS and NO in rat spleen were very similar to those of iNOS. The results indicated the degree of the iNOS activity in rat spleen was positively correlated to the severity of psychological stress. In addition, exceeding NO induced by the increased iNOS during stress might be one of the cause for decreasing immunoactivity of the stressed rats. Fig 1, Tab 2, Ref 10