Kull B, Svenningsson P, Fredholm B B
Department of Physiology and Pharmacology, Section of Molecular Neuropharmacology, Karolinska Institutet, Stockholm, Sweden.
Mol Pharmacol. 2000 Oct;58(4):771-7. doi: 10.1124/mol.58.4.771.
In situ hybridization with cRNA probes showed A(2A) receptor and G(olf) mRNAs to be abundantly expressed in caudate putamen, nucleus accumbens, and olfactory tubercle, whereas G(s) mRNA shows a comparatively low expression in regions expressing A(2A) receptors. In caudate putamen, 49% of the medium-sized neuron-like cells exhibited a strong signal for adenosine A(2A) receptor mRNA, and 98% showed a strong signal for G(olf) mRNA. In contrast, G(s) mRNA was found in only 12% of the medium-sized neuron-like cells in caudate putamen. The coexpression of adenosine A(2A) receptor mRNA with that of G(olf) or G(s) mRNAs was studied with double in situ hybridization. A large majority (91-95%) of the neurons in caudate-putamen that contained adenosine A(2A) receptor mRNA also expressed G(olf) mRNA, whereas only 3 to 5% of the neurons with adenosine A(2A) receptor mRNA coexpressed G(s) mRNA. The A(2A) receptor agonist CGS 21680 [2-[p-(2-carbonylethyl)phenylethylamino-5'-N-ethylcarboxa midoadenosin e] dose dependently activated G(olf) subunits in striatal membranes as shown by photolabeling with [alpha-(32)P]m-acetylanilido-GTP followed by immunoprecipitation with a specific antibody against G(olf). Transfection of G(olf) cDNA into Chinese hamster ovary cells, which stably express human adenosine A(2A) receptors, led to an increased efficacy of CGS 21680, as evidenced by a stronger cAMP response, indicating that activation of G(olf) by A(2A) receptors leads to a biological signal. In conclusion, these results provide anatomical and biochemical evidence that adenosine A(2A) receptors stimulate G(olf) rather than G(s) in striatum.
用cRNA探针进行的原位杂交显示，A(2A)受体和G(olf) mRNA在尾状壳核、伏隔核和嗅结节中大量表达，而G(s) mRNA在表达A(2A)受体的区域中表达相对较低。在尾状壳核中，49%的中等大小神经元样细胞对腺苷A(2A)受体mRNA呈现强信号，98%对G(olf) mRNA呈现强信号。相比之下，在尾状壳核中仅12%的中等大小神经元样细胞中发现有G(s) mRNA。采用双重原位杂交研究腺苷A(2A)受体mRNA与G(olf)或G(s) mRNA的共表达情况。尾状壳核中含有腺苷A(2A)受体mRNA的大多数神经元（91 - 95%）也表达G(olf) mRNA，而只有3%至5%含有腺苷A(2A)受体mRNA的神经元共表达G(s) mRNA。A(2A)受体激动剂CGS 21680 [2 - [对 - (2 - 羰基乙基)苯乙基氨基 - 5'-N - 乙基羧酰胺腺苷] 如通过用[α - (32)P] - m - 乙酰苯胺基 - GTP进行光标记然后用针对G(olf)的特异性抗体进行免疫沉淀所示，剂量依赖性地激活纹状体膜中的G(olf)亚基。将G(olf) cDNA转染到稳定表达人腺苷A(2A)受体的中国仓鼠卵巢细胞中，导致CGS 21680的效力增加，如更强的cAMP反应所证明，表明A(2A)受体对G(olf)的激活导致生物信号。总之，这些结果提供了解剖学和生化证据，表明腺苷A(2A)受体在纹状体中刺激G(olf)而非G(s)。
