Hohmann A G, Herkenham M
Section on Functional Neuroanatomy, National Institute of Mental Health, Bethesda, MD 20892-4070, USA.
Neuroscience. 1999 Mar;90(3):923-31. doi: 10.1016/s0306-4522(98)00524-7.
In situ hybridization histochemistry was used to show the distribution of messenger RNA for central cannabinoid CB 1 receptors in dorsal root ganglia of the rat. CB1 messenger RNA was highly expressed in neuronal subpopulations of rat dorsal root ganglia. The phenotypes of neurons that express messenger RNA for CB1 were subsequently examined by combining a 35S-labeled ribonucleotide probe for CB1 messenger RNA with digoxigenin-labeled riboprobes for preprotachykinin A (substance P precursor), alpha-calcitonin gene-related peptide and preprosomatostatin (somatostatin precursor) messenger RNAs. Qualitative examination revealed expression of CBI messenger RNA predominantly in medium-and large-sized cells distributed throughout the dorsal root ganglia. The majority of neurons expressing substance P messenger RNA were CB1 messenger RNA negative and smaller in size than the CB1 messenger RNA-positive cells. Only 13% of substance P messenger RNA-positive cells expressed CB1 messenger RNA. A similar degree of co-localization was observed with alpha-calcitonin gene-related peptide: 10% of cells expressing messenger RNA for this neuropeptide were CB1 messenger RNA positive. Co-localization of CB1 and somatostatin messenger RNAs was observed in less than 0.5% of somatostatin messenger RNA-positive cells. The data suggest that subpopulations of neurons in rat dorsal root ganglia are capable of synthesizing cannabinoid receptors and inserting them on terminals in the superficial dorsal horn. These findings provide anatomical evidence for cannabinoid modulation of primary afferent transmission. Although an anatomical basis for cannabinoid-mediated suppression of release of neurogenic peptides from nociceptive primary afferents is provided, our results demonstrate that the majority of CB messenger RNA-positive neurons in the dorsal root ganglia contain transmitters and/or neuromodulators other than the neuropeptides examined herein.
原位杂交组织化学法用于显示大鼠背根神经节中中枢大麻素CB1受体信使核糖核酸（mRNA）的分布。CB1 mRNA在大鼠背根神经节的神经元亚群中高度表达。随后，通过将用于CB1 mRNA的35S标记核糖核苷酸探针与用于前速激肽原A（P物质前体）、α-降钙素基因相关肽和前促生长抑素（生长抑素前体）mRNA的地高辛标记核糖探针相结合，对表达CB1 mRNA的神经元表型进行了检测。定性检测显示，CB1 mRNA主要在分布于整个背根神经节的中型和大型细胞中表达。大多数表达P物质mRNA的神经元CB1 mRNA呈阴性，且细胞大小比CB1 mRNA阳性细胞小。仅13%的P物质mRNA阳性细胞表达CB1 mRNA。对于α-降钙素基因相关肽，观察到了类似程度的共定位：表达该神经肽mRNA的细胞中，10% CB1 mRNA呈阳性。在不到0.5%的生长抑素mRNA阳性细胞中观察到了CB1和生长抑素mRNA的共定位。数据表明，大鼠背根神经节中的神经元亚群能够合成大麻素受体并将其插入浅表背角的终末。这些发现为大麻素对初级传入神经传递的调节提供了解剖学证据。尽管为大麻素介导的伤害性初级传入神经释放神经源性肽的抑制作用提供了解剖学基础，但我们的结果表明，背根神经节中大多数CB mRNA阳性神经元含有本文所检测神经肽以外的递质和/或神经调质。
