功能性ghrelin受体在内脏迷走和脊髓传入神经通路中的表达

Expression of growth hormone secretagogue receptor type 1a in visceral vagal and spinal afferent parthways

本文在mRNA和蛋白水平观察了功能性ghrelin受体(growth hormone secretagogue receptortype 1a,GHS-R1a)在大鼠内脏迷走及脊髓传入神经通路中的表达。结果显示:(1)GHS-R1a免疫反应阳性神经元及GHS-R1amRNA分布于背根神经节(dorsalroot ganglion,DRG)及结状神经节(nodose ganglion,NG)。(2)应用免疫双标技术观察到DRG和NG中都有一些GHS-R1a免疫反应阳性神经元,同时降钙素基因相关肽(calcitoningene-related peptide,CGRP)染色呈阳性,显示GHS-R1a和CGRP共存于同一神经元,表明内脏传入神经元存在许多亚核群。(3)应用荧光金(fluorogold)标记的神经逆行追踪技术对从胃投射到DRG和NG的神经元进行免疫组织化学染色,观察到一些表达CGRP的GHS-R1a免疫反应阳性神经元也被荧光金染色。上述实验结果证实了GHS-R1a在迷走神经和脊髓传入神经元中的表达,提示ghrelin参与了胃-脑轴的调节。

In this study, the expressions of growth hormone secretagogue receptor type 1a （GHS-R1a） in the rat dorsal root ganglion （DRG） and nodose ganglion （NG） were investigated by using immunohistochemistry and in situ hybridization. The results clearly showed the presence of GHS-R1a mRNA and GHS-R1a-positive neurons in the rat DRG and NG. GHS-R1a was also co-localized with calcitonin gene-related peptide （CGRP） in some DRG and NG neurons, indicating the existence of subpopulations of the visceral afferents. The extrinsic primary afferent visceroceptive DRG and NG neurons from the stomach were identified by retrograde tracing fluorogold and stained for GHS-R1a and CGRP. Some neurons both positive for CGRP and GHS-R1a were labled by fluorogold. Our results not only demonstrate the expression of GHS-R1a in the vagal afferents but also provide the fwst and direct morphological evidence for its presence in the spinal visceral afferents, and gherin might have a modulatory role in the visceral afferent signaling.