大鼠前扣带回皮质5-HT1A，1B,2A，2C受体亚型蛋白表达的细胞定位

Cellular localization of 5-HT_(1A,1B,2A,2C) receptor subtype proteins in anterior cingulate cortex of rat

目的:观察5-HT_(1A、1B)和5HT_(2A、2C)等受体在大鼠前扣带回皮质(anterior cingulated cortex,ACC)的分布及细胞定位。方法:将20只成年雄性Sprague-Dawley大鼠平均分成四组,每组5只分别进行四种亚型5-HT的免疫组织化学反应。动物经过灌注固定、脑冠状切片(25μm)后,以卵白素-生物素复合物法(ABC法)对切片进行染色、显微镜观察。结果:四种5-HT受体亚型在ACC都有分布。ACC内II-VI层均有5-HT_(1A)免疫阳性反应神经元的胞体和树突。5-HT_(1B)受体亚型定位在神经元胞体上,表达较弱。I-III层5-HT_(2A)免疫阳性反应较强,主要为标记的锥体神经元树突(Cg1区III层观察到部分阳性反应的神经元胞体);而V-VI层可见到明显的免疫阳性神经元胞体。5-HT2C受体定位于ACC之II-VI层神经元胞体上。结论:5-HT_(1A)、5-HT_(1B)、5-HT_(2A)和5-HT_(2C)等不同受体亚型在ACC内细胞上的定位有一定差异,提示它们介导5-HT对ACC神经元发生调节反应的细胞作用部位有选择性,因之它们介导的5-HT对ACC神经元的作用效果也可能不同。

Objective： To examine the laminar distribution and cellular localization of 5-hydroxytryptamine （5-HT） receptor subtype proteins of 5-HT1A, 1B and 5-HT2A, 2C in the anterior cingulate cortex （ACC） of rat. Methods： A total of twenty normal male Sprague-Dawley （SD） rats were used, which were equally divided into four groups of five rats each, immunohistochemistry for the four subtypes of 5-HT receptors, respectively. Animals were fixed via perfusion and brains were cut into coronal slices in 25 μm thickness. Sections were immunostained with Avidin-Biotin Complex （ABC） method before observation with light microscopy. Results： Immunoreactivities of all four 5-HT receptor subtypes were detected throughout the whole rostrocaudal extent of ACC. Laminae II through to VI of ACC contained 5-HT1A im- munopositive cell bodies and dendrites; 5-HT1B receptor was localized to cell bodies as shown by relatively weak immu- noreactivity. High intensity of 5-HT2A immnnolabeling was present in laminae I to III of ACC, appearing as labeled dendrites of pyramidal neurons with the presence of additional labeled cell bodies in layer III of area 1 （ Cgl ） ; while laminae V and VI witnessed 5-HT2A immunopositive neuronal cell bodies. 5-HT2C receptor was localized to neuronal cell bodies of laminae II through to VI. Conclusion： Laminar distribution and cellular localization with respect to 5-HT1A ,5-HT1B, 5-HT2A and 5-HT2C receptors showed distinguishable difference, suggesting the selectivity of the individual receptors in cellular compartments for mediation of 5-HT actions, which may yield different effects of 5-HT on the resuhing activity of ACC neurons .