Khan Z U, Gutiérrez A, Martín R, Peñafiel A, Rivera A, De La Calle A
Department of Cell Biology, Faculty of Science, University of Malaga, Spain.
J Comp Neurol. 1998 Dec 21;402(3):353-71. doi: 10.1002/(sici)1096-9861(19981221)402:3<353::aid-cne5>3.0.co;2-4.
Dopamine D2-like receptors (D2, D3, and D4) are major targets for action of typical and atypical neuroleptics, commonly used in the treatment of schizophrenia. To understand their individual functional contribution, subtype-selective anti-peptide antibodies were raised against D2, D3, and D4 receptor proteins. The antibodies were shown to be specific on immunoblots of rat brain membranes and immunoprecipitated the solubilized native dopamine receptors in an antibody concentration-dependent manner. In addition, they also bind selectively to the respective recombinant D2, D3, and D4 receptor membrane proteins from cDNA transfected cells. Immunolocalization studies show that the D2-like receptor proteins had differential regional and cellular distribution in the cerebral cortex, hippocampus, basal ganglia, cerebellum, and midbrain, thus providing anatomical substrate for area-specific regulation of the dopamine neurotransmission. In cortical neurons, D4 receptor protein was found in both pyramidal and nonpyramidal cells, whereas D2 and D3 seem to be mostly associated with nonpyramidal interneurons. In rat hippocampus, the expression pattern of D2-like receptors (D4>D3>D2) mirrored that obtained with immunoprecipitation studies. D2 and D4 receptor immunolabeling was observed in the thalamic reticular nucleus, which was negative for the D3 subtype. Species differences were also observed; for example, the D4 subtype receptor is the most highly expressed protein in the rat cortex, whereas it is significantly less in human cortex. Differential patterns of D2, D3, and D4 receptor expression in rat and human brain should shed light on the therapeutic actions of neuroleptic drugs and may lead to the development of more specifically targeted antipsychotic drugs.
多巴胺D2样受体（D2、D3和D4）是常用于治疗精神分裂症的典型和非典型抗精神病药物的主要作用靶点。为了解它们各自的功能作用，制备了针对D2、D3和D4受体蛋白的亚型选择性抗肽抗体。这些抗体在大鼠脑膜免疫印迹上显示具有特异性，并以抗体浓度依赖的方式免疫沉淀溶解的天然多巴胺受体。此外，它们还能选择性地结合来自cDNA转染细胞的相应重组D2、D3和D4受体膜蛋白。免疫定位研究表明，D2样受体蛋白在大脑皮层、海马体、基底神经节、小脑和中脑具有不同的区域和细胞分布，从而为多巴胺神经传递的区域特异性调节提供了解剖学基础。在皮层神经元中，D4受体蛋白存在于锥体细胞和非锥体细胞中，而D2和D3似乎主要与非锥体中间神经元相关。在大鼠海马体中，D2样受体（D4>D3>D2）的表达模式与免疫沉淀研究结果一致。在丘脑网状核中观察到D2和D4受体免疫标记，而D3亚型为阴性。还观察到种属差异；例如，D4亚型受体是大鼠皮层中表达最高的蛋白，而在人类皮层中表达明显较低。大鼠和人类大脑中D2、D3和D4受体的不同表达模式应有助于阐明抗精神病药物的治疗作用，并可能导致开发更具特异性靶点的抗精神病药物。
