摘要
目的研究Long Evans大鼠出生后视皮层组织型纤溶酶原激活剂(tPA)分布、表达、活性的变化及与视皮层可塑性关键期终止的关系。方法Long Evans大鼠131只按出生后周龄分为1、3、5、7、14周共5组,免疫荧光组织化学法定位检测tPA的分布,免疫印迹定量法检测视皮层总蛋白中tPA的表达,发色底物酶活性分析法测定视皮层tPA的活性。结果除1周组外,各组视皮层Ⅱ-Ⅲ层、Ⅳ层tPA免疫荧光呈阳性,主要分布在Ⅱ-Ⅲ层(P<0.01)。Ⅱ-Ⅲ层以5周组tPA阳性细胞密度最高(P<0.01),14周组最低(P<0.01);Ⅳ层以3周组tPA阳性细胞密度最高,14周组最低(P<0.01)。除1周组外,各组视皮层总蛋白中tPA均有表达,5周组最高(P<0.05),14周组最低(P<0.05)。视皮层tPA活性3周组最低(P<0.01),5周组最高(P<0.01)。结论tPA参与视皮层可塑性关键期的“终止”,可能是Ⅱ-Ⅲ层、Ⅳ层之间突触可塑性存在异质性的结构基础之一。
Objective To investigate the distribution ,expression and activity of tissue-type plasminogen activator (tPA) in visual cortex of Long Evans rat during postnatal development and explore the relationship between these developing changes and closure of critical period of visual cortex plasticity. Methods According to postnatal age, rats (n = 131 )were divided into 1 week (before eye opening) ,3 weeks (peak),5 weeks (later stage),7 weeks (termination of critical period),and 14 weeks (adult) groups. Distribution and expression of tPA were detected using immunofluorescence histochemistry and Western blot respectively. The tPA activity in visual cortex was determined by a chromogenic assay kit. Results No tPA was found in visual cortex in the rats of 1 week group;while in the other groups,tPA was seen in the layers Ⅱ-Ⅲ and Ⅳ of visual cortex with major location of tPA in layer Ⅱ-Ⅲ(P 〈0. 01). In layer Ⅱ-Ⅲ of rats in 5 weeks group, the density of tPA-containing cells reached peak (3 190. 2 ± 237.3 cells/mm^2 ), and then reduced to minimum at postnatal 14 weeks ( 1 364. 2 ± 233.0 cells/mm^2 ). In the layer IV of rats in 3 weeks, the density of tPA-containing cells attached the maximum( 1 667. 4 ± 362. 8 cells/mm^2) and then decreased to the minimum at postnatal 14 weeks(474. 9 ± 86. 7 cells/mm^2, P 〈0. 01 ). Western blot analysis indicated that tPA was detected in visual cortex in rats in 3,5,7 and 14 weeks groups with the highest quantity in the 5 weeks group (40. 81% ± 4. 30% )and the lowest expression in the 14 weeks group ( 10. 23% ± 2. 89% ). The tPA activity was lowest in 3 weeks group(44. 78 ± 3. 47 × 10 ^-2 U/mg) and then raised peak in 5 weeks group ( 105.41 ± 4. 39 × 10^ -2 U/mg). Conclusion tPA participates in closure of critical period of visual cortex plasticity. It may be one of the structural factors underlying the synaptic plasticity heterogeneity between layer Ⅱ-Ⅲ and layer Ⅳ.
出处
《眼科研究》
CSCD
北大核心
2007年第4期241-244,共4页
Chinese Ophthalmic Research
基金
国家杰出青年科学基金(30025014)
国家自然科学基金(30672280)资助