大鼠下丘脑亨廷顿蛋白相关蛋白1异构体HAP1A和HAP1B的表达

Expression of two isomeride of huntingtin-associated protein 1,HAP1A and HAP1B,in the hypothalamus of the rat

目的观察2种亨廷顿蛋白相关蛋白1(huntingtin-associated protein 1,HAP1)异构体HAP1A和HAP1B在大鼠下丘脑的分布特点。方法取Wistar雄性大鼠的脑,经恒冷箱冰冻切片,片厚30μm,进行HAP1A和HAP1B的免疫组织化学ABC法和免疫荧光双标法染色。结果免疫组织化学ABC法结果显示,HAP1A与HAP1B在成年大鼠下丘脑免疫反应阳性产物分布区域无明显差异,免疫阳性物质呈棕褐色,以视前内侧区、前区、视上核、室旁核、弓状核、结节核、腹内侧核等部位表达水平较高,其他核团呈较低水平表达。HAP1A免疫反应阳性产物主要以颗粒状形式定位在Stigmoid小体上,在神经元胞体和近端突起的胞质内弥散分布产物极少,阳性强度极弱,神经元胞体轮廓不明显;而HAP1B免疫反应阳性产物则主要以弥散形式定位于神经元胞质内,神经元胞体轮廓十分清楚;HAP1B免疫反应阳性产物还弥散、均匀分布在神经毡内,或定位于Stigmoid小体上,但HAP1B阳性Stigmoid小体数量明显少于HAP1A阳性者。免疫荧光双标记法结果显示,约有80%的Stigmoid小体既含有HAP1A也含有HAP1B,其余的Stig-moid小体仅含HAP1A。结论 HAP1A和HAP1B在大鼠下丘脑内具有相同的区域分布模式,但在神经元内的定位具有明显区别,提示二者可能具有不同的功能;HAP1A或其羧基末端片段更适合于作为Stigmoid小体的标志物。

Objective To observe the distributive features of two isoforms of huntingtin-associated protein 1（HAP1）,HAP1A and HAP1B,in the hypothalamus of the rat. Methods The frozen sections of the male Wistar rats′ brains were sliced in the cryostat microtome,which were 30 μm thick.HAP1A and HAP1B were stained by ABC method of immunohistochemistry and immunofluorescent double labeling method. Results The immunohistochemistry staining showed that the distributive regions of HAP1A were similar to those of HAP1B in the hypothalamus of the rat.Both HAP1A and HAP1B were expressed with the higher level in medial preoptic area,anterior region,supraoptic nucleus,paraventricular nucleus,arcuate nuclei,tuberal nucleus,ventromedial nucleus,and with the lower level in the other nuclei of the hypothalamus.In the neurons,HAP1A-immunoreactive products were mainly localized in the Stigmoid bodies but very few in the perikaryon and proximal processes.The HAP1B immunoreactivity was very strong and the immunoreactive products were diffusely and evenly distributed in the perikaryon and proximal processes.Some Stigmoid bodies were also positive for HAP1B immunoreactivity.Immunofluorescent double labelling showed that approximately 80%of Stigmoid bodies expressed both HAP1A and HAP1B,and the remaining expressed HAP1A only. Conclusion HAP1A has the same regional distribution pattern as HAP1B does in the hypothalamus,but in the neurons,they have different localization,suggesting that HAP1A might have different functions from HAP1B.HAP1A or its carboxy terminal sequence may be a more effective marker for Stigmoid bodies.