5-HT及其2A受体在大鼠丘脑前核的表达

目的研究5-羟色胺(5-HT)及其5-羟色胺2A受体(5-HT2AR)在大鼠丘脑前核的表达,探讨两者参与学习记忆的形态学依据。方法免疫组织化学ABC法观察5-HT及5-HT2AR在丘脑前核内的表达情况。包埋前免疫电镜技术观察丘脑前核群的5-HT能投射纤维终末。结果免疫组化结果显示:在大鼠丘脑前核群的前、中、后部均可见阳性的5-HT能神经元及大量串珠状的投射纤维终末,其中背侧核(AD)的神经元着色较深,胞体较大,纤维密集,平均光密度值(A值)与腹侧核(AV)的比较差异显著(P0.05);5-HT阳性反应产物主要定位于胞浆内,胞核不着色。包埋前免疫电镜显示:阳性5-HT能轴突终末与树突形成非对称性的轴-树突触。在AD、AV内可见黄色的5-HT2AR阳性神经元,其中AD的神经元胞体较大,着色较AV深,阳性产物灰度值二者比较差异显著(P0.05);阳性产物主要定位于神经元胞膜,胞核不着色。结论 5-HT和5-HT2AR在大鼠丘脑前核表达,在AD、AV的表达强度不同。

Expression of 5-HT and 5-HT2AR in the anterior thalamic nuclei of rat

Objective To study the expression of 5-HT and 5-HT2AR in the anterior thalamic nuclei （ATN） of rat to explore the morphology of 5-HT and 5-HT2AR in learning and memory. Methods Immunohistochemical staining method（ABC） was used to demonstrate the expression of 5-HT and 5-HT2AR in ATN of rats, the pre-embedding immunohistochemical staining was used to demonstrate 5-HT positive axon terminal. Results A large amount of 5-HT positive neurons and dense axon terminals were distributed throughout the ATN. In the anterior dorsal nucleus（AD）, distribution of positive neurons and axon terminals were intensive, with much heavier staining and larger cell body in AD compared with the anterior ventral thalamic nucleus（AV, P〈0.05）. 5-HT positive substance was found chiefly in the cytoplasm, not in the nucleus. In ATN, 5-HT positive terminals containing clear round synaptic vesicles formed asymmetric synapse with dendrites. 5-HT2AR positive neurons were seen in ATN, with more intensive staining and larger cell body in AD compared with AV（ P〈0.05）. The 5-HT2AR-like immunoreactivities were located chiefly on the membrane, not in nucleus. Conclusion 5-HT and 5-HT2AR were richly expressed in neurons and fibers in the anterior thalamic nuclei, with different expression level between AD and AV.