Kashiba H, Fukui H, Senba E
Department of Physiology, Kansai College of Oriental Medicine, 2-11-1 Wakaba, Kumatori, Sennan, 590-0433, Osaka, Japan.
Brain Res. 2001 May 18;901(1-2):85-93. doi: 10.1016/s0006-8993(01)02287-9.
Histamine H1 receptor mRNA-expressing sensory neurons in guinea pigs are unmyelinated and are not immunoreactive to substance P and calcitonin gene-related peptide (CGRP) [Mol. Brain Res. 66 (1999) 24], which are implicated in the nociceptive transmission of the primary sensory system. In this study, we examined whether these H1 receptor mRNA-expressing neurons are sensitive to capsaicin by using in situ hybridization histochemistry. Of lumbar dorsal root ganglion (DRG) neurons in control animals, 17% were positive for CGRP. In guinea pigs neonatally treated with capsaicin (50 mg/kg), few CGRP-immunoreactive neurons were seen in the DRGs. However, the percentages of H1 receptor mRNA-expressing neurons (15-20%) and the intensity of the mRNA signals in these neurons were not affected by neonatal capsaicin treatment. We also revealed the presence of both capsaicin-sensitive and insensitive neuropeptide Y (NPY)-immunoreactive neurons in the DRGs. These neurons were exclusively small. H1 receptor mRNA was expressed in NPY-immunoreactive neurons in naive guinea pig DRGs. These results suggest that H1 receptor mRNA is expressed in capsaicin-insensitive DRG neurons with NPY-immunoreactivity in guinea pigs.
豚鼠中表达组胺H1受体mRNA的感觉神经元无髓鞘，且对P物质和降钙素基因相关肽（CGRP）无免疫反应性[《分子脑研究》66(1999)24]，而P物质和CGRP与初级感觉系统的伤害性传递有关。在本研究中，我们通过原位杂交组织化学检查这些表达H1受体mRNA的神经元是否对辣椒素敏感。在对照动物的腰背根神经节（DRG）神经元中，17%的神经元CGRP呈阳性。在用辣椒素（50mg/kg）进行新生期处理的豚鼠中，DRG中几乎未见CGRP免疫反应性神经元。然而，表达H1受体mRNA的神经元的百分比（15 - 20%）以及这些神经元中mRNA信号的强度不受新生期辣椒素处理的影响。我们还发现DRG中存在对辣椒素敏感和不敏感的神经肽Y（NPY）免疫反应性神经元。这些神经元均为小神经元。在未处理的豚鼠DRG中，NPY免疫反应性神经元表达H1受体mRNA。这些结果表明，在豚鼠中，H1受体mRNA在具有NPY免疫反应性的对辣椒素不敏感的DRG神经元中表达。
