Noguchi K, De León M, Nahin R L, Senba E, Ruda M A
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892.
J Neurosci Res. 1993 May 1;35(1):54-66. doi: 10.1002/jnr.490350108.
Alteration in mRNA expression in dorsal root ganglia (DRG) neurons encoding 5 neuropeptides was quantitatively compared in normal rats and in those neonatally treated with capsaicin, a selective neurotoxin which destroys a subpopulation of DRG neurons with unmyelinated axons. Adult rats received a unilateral transection of the sciatic nerve and were killed 7 days later. Oligonucleotide probes specific for the genes encoding neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), galanin (GAL), somatostatin (SOM), and calcitonin gene-related peptide (CGRP) were used for in situ hybridization and RNA blot analysis. Following the nerve cut, RNA blot analysis demonstrated a dramatic induction of NPY, VIP, and GAL mRNA levels from the undetectable constitutive level of expression. Conversely, CGRP and SOM mRNAs, which are constitutively expressed, were reduced 55% and 70%, respectively, following the nerve cut. A unimodal size distribution for neurons expressing NPY mRNA was determined, with a mean cross-sectional area of 1700 microns2 representing 24.4% of DRG neurons ipsilateral to the nerve cut. Neurons expressing VIP mRNA were mainly small sized, with a cross-sectional area of approximately 700 microns2, while those expressing GAL mRNA were both small (approximately 700 microns2) and medium (approximately 1,300 microns2) sized. The percentages of neurons expressing VIP or GAL mRNA were 19.9% and 33.7%, respectively. In neonatal capsaicin-treated rats, there was a 10% reduction in neurons expressing NPY mRNA, a 37% reduction for VIP, and a 27% for GAL mRNA compared to vehicle-treated rats after nerve cut. Capsaicin-sensitive neurons comprised 37% of CGRP neurons and 83% of SOM neurons. These observations suggest that NPY is primarily induced in myelinated primary afferent neurons, while VIP and GAL mRNA induction occurs in a mixed population, a sizeable percentage of which has unmyelinated axons. Additionally, SOM mRNA expression is associated mainly with unmyelinated primary afferents.
对正常大鼠以及新生期用辣椒素处理过的大鼠背根神经节（DRG）神经元中编码5种神经肽的mRNA表达变化进行了定量比较。辣椒素是一种选择性神经毒素，可破坏具有无髓轴突的DRG神经元亚群。成年大鼠接受坐骨神经单侧横断，7天后处死。使用针对神经肽Y（NPY）、血管活性肠肽（VIP）、甘丙肽（GAL）、生长抑素（SOM）和降钙素基因相关肽（CGRP）编码基因的寡核苷酸探针进行原位杂交和RNA印迹分析。神经切断后，RNA印迹分析显示NPY、VIP和GAL mRNA水平从不可检测的组成性表达水平显著诱导升高。相反，组成性表达的CGRP和SOM mRNA在神经切断后分别降低了55%和70%。确定了表达NPY mRNA的神经元的单峰大小分布，平均横截面积为1700平方微米，占神经切断同侧DRG神经元的24.4%。表达VIP mRNA的神经元主要为小尺寸，横截面积约为700平方微米，而表达GAL mRNA的神经元既有小尺寸（约700平方微米）也有中尺寸（约1300平方微米）。表达VIP或GAL mRNA的神经元百分比分别为19.9%和33.7%。在新生期用辣椒素处理的大鼠中，与神经切断后用赋形剂处理的大鼠相比，表达NPY mRNA的神经元减少了10%，VIP减少了37%，GAL mRNA减少了27%。对辣椒素敏感的神经元占CGRP神经元的37%和SOM神经元的83%。这些观察结果表明，NPY主要在有髓初级传入神经元中诱导产生，而VIP和GAL mRNA的诱导发生在混合群体中，其中相当大比例的神经元具有无髓轴突。此外，SOM mRNA表达主要与无髓初级传入神经有关。
