Oda Satoko, Funato Hiromasa
Department of Anatomy, Graduate School of Medicine, Toho University, Tokyo, Japan.
International Institute for Integrative Sleep Medicine (IIIS), University of Tsukuba, Tsukuba, Japan.
Front Neuroanat. 2023 Feb 14;17:1111008. doi: 10.3389/fnana.2023.1111008. eCollection 2023.
Pial astrocytes, a cellular component of the cerebral cortex surface structure, are observed in a wide range of mammalian species. Despite being recognized as such, the functional potential of pial astrocytes has long been overlooked. Our previous research demonstrated that pial astrocytes exhibit stronger immunoreactivity for muscarinic acetylcholine receptor M1 than protoplasmic astrocytes, indicating sensitivity to neuromodulators. Here, we examined whether pial astrocytes express receptors for dopamine, another crucial neuromodulator of cortical activity. We investigated the immunolocalization of each dopamine receptor subtype (D1R, D2R, D4R, D5R) in the rat cerebral cortex, and compared the intensity of immunoreactivity between pial astrocytes, protoplasmic astrocytes, and pyramidal cells. Our findings revealed that pial astrocytes and layer I astrocytes exhibit stronger D1R- and D4R-immunoreactivity than D2R and D5R. These immunoreactivities were primarily localized in the somata and thick processes of pial and layer I astrocytes. In contrast, protoplasmic astrocytes located in cortical layers II-VI displayed low or negligible immunoreactivities for dopamine receptors. D4R- and D5R-immunopositivity was distributed throughout pyramidal cells including somata and apical dendrites. These findings suggest that the dopaminergic system may regulate the activity of pial and layer I astrocytes D1R and D4R.
软脑膜星形胶质细胞是大脑皮质表面结构的一种细胞成分，在多种哺乳动物物种中都有观察到。尽管如此，软脑膜星形胶质细胞的功能潜力长期以来一直被忽视。我们之前的研究表明，与原浆性星形胶质细胞相比，软脑膜星形胶质细胞对毒蕈碱型乙酰胆碱受体M1表现出更强的免疫反应性，表明其对神经调质敏感。在这里，我们研究了软脑膜星形胶质细胞是否表达多巴胺受体，多巴胺是另一种对皮质活动至关重要的神经调质。我们研究了大鼠大脑皮质中每种多巴胺受体亚型（D1R、D2R、D4R、D5R）的免疫定位，并比较了软脑膜星形胶质细胞、原浆性星形胶质细胞和锥体细胞之间的免疫反应强度。我们的研究结果表明，软脑膜星形胶质细胞和I层星形胶质细胞对D1R和D4R的免疫反应性比D2R和D5R更强。这些免疫反应主要定位于软脑膜和I层星形胶质细胞的胞体和粗突起中。相比之下，位于皮质II-VI层的原浆性星形胶质细胞对多巴胺受体的免疫反应性较低或可忽略不计。D4R和D5R免疫阳性分布在包括胞体和顶端树突在内的整个锥体细胞中。这些发现表明，多巴胺能系统可能通过D1R和D4R调节软脑膜和I层星形胶质细胞的活性。
