Gold M S, Dastmalchi S, Levine J D
Department of Medicine, University of California, San Francisco 94143-0452, USA.
Pain. 1997 Jan;69(1-2):179-90. doi: 10.1016/s0304-3959(96)03218-6.
To determine which alpha 2-adrenergic receptor subtypes are present in primary afferent and sympathetic postganglionic neurons we have performed in situ hybridization and immunohistochemistry experiments on rat dorsal root and superior cervical ganglia. Reverse transcriptase polymerase chain reaction was used as a preliminary screen for the presence of mRNA encoding alpha 2-adrenergic subtypes in dorsal root and superior cervical ganglia; polymerase chain reaction primers amplified distinct regions of the rat alpha 2A-(RG20), alpha 2B-(RNG) and alpha 2C-(RG10) adrenergic receptor subtypes in mRNA extracted from lumbar dorsal root and superior cervical ganglia. To localize receptors to cell types in the ganglia, in situ hybridization was performed on cryosections of dorsal root and superior cervical ganglia with oligonucleotide probes designed to distinguish between mRNA encoding for alpha 2-adrenergic receptor subtypes. Immunohistochemistry was performed with a polyclonal antibody against the alpha 2A-adrenergic receptor subtype. Our results with reverse transcriptase polymerase chain reaction indicate that all three alpha 2-adrenergic receptor subtypes are expressed in dorsal root and superior cervical ganglia. Data from the in situ hybridization experiments indicated that the mRNA detected with the reverse transcriptase polymerase chain reaction was present in neuronal cell bodies, except for the mRNA encoding the alpha 2A-adrenergic receptor which was not detectable in dorsal root ganglia. The distribution of mRNA encoding alpha 2B- and alpha 2C-adrenergic receptor subtypes among dorsal root ganglion neurons and alpha 2A-, alpha 2B- and alpha 2C-adrenergic receptor subtypes among superior cervical ganglion neurons suggests that multiple adrenergic receptor subtypes are present in a single neuron. Neuronal cell bodies in both the dorsal root and superior cervical ganglion consistently demonstrated alpha 2A-adrenergic receptor-like immunoreactivity. The apparent co-expression of multiple alpha 2-adrenergic receptor subtypes in dorsal root and superior cervical ganglion neurons enables a single transmitter to produce a number of effects in the same neuron; which receptors are functionally active may vary with the presence of nerve injury, inflammation or other physiological and pathophysiological conditions.
为了确定初级传入神经元和交感神经节后神经元中存在哪些α₂-肾上腺素能受体亚型，我们对大鼠背根神经节和颈上神经节进行了原位杂交和免疫组织化学实验。逆转录聚合酶链反应被用作初步筛选，以检测背根神经节和颈上神经节中编码α₂-肾上腺素能受体亚型的mRNA的存在；聚合酶链反应引物在从腰段背根神经节和颈上神经节提取的mRNA中扩增出大鼠α₂A-（RG20）、α₂B-（RNG）和α₂C-（RG10）肾上腺素能受体亚型的不同区域。为了将受体定位到神经节中的细胞类型，我们用设计用于区分编码α₂-肾上腺素能受体亚型的mRNA的寡核苷酸探针，对背根神经节和颈上神经节的冰冻切片进行了原位杂交。用针对α₂A-肾上腺素能受体亚型的多克隆抗体进行了免疫组织化学实验。我们逆转录聚合酶链反应的结果表明，所有三种α₂-肾上腺素能受体亚型均在背根神经节和颈上神经节中表达。原位杂交实验的数据表明，逆转录聚合酶链反应检测到的mRNA存在于神经元细胞体中，但编码α₂A-肾上腺素能受体的mRNA在背根神经节中未检测到。编码α₂B-和α₂C-肾上腺素能受体亚型的mRNA在背根神经节神经元中的分布，以及α₂A-、α₂B-和α₂C-肾上腺素能受体亚型在颈上神经节神经元中的分布表明，单个神经元中存在多种肾上腺素能受体亚型。背根神经节和颈上神经节中的神经元细胞体始终表现出α₂A-肾上腺素能受体样免疫反应性。背根神经节和颈上神经节神经元中多种α₂-肾上腺素能受体亚型的明显共表达，使得单一递质能够在同一神经元中产生多种效应；哪些受体具有功能活性可能会因神经损伤、炎症或其他生理和病理生理状况的存在而有所不同。
