Zerari-Mailly Fouzia, Braud Adeline, Davido Nicolas, Touré Babacar, Azérad Jean, Boucher Yves
UFR de Biologie, Université Diderot, Paris, France.
Eur J Oral Sci. 2012 Oct;120(5):402-7. doi: 10.1111/j.1600-0722.2012.00989.x. Epub 2012 Aug 22.
Glutamate is present in primary sensory afferents innervating the dental pulp and is known to exert vasoactive effects. The aims of this study were (i) to assess pulpal blood flow (PBF) after glutamate infusion in the dental pulp and (ii) to observe the distribution of glutamatergic nerve fibers expressing the vesicular transporters of glutamate (VGluT). The PBF was monitored with laser Doppler flowmetry before and after glutamate (0.5 M) infusion in the dental pulp vs. saline infusion. Immunochemistry for VGluT1, 2, and 3 was performed in addition to immunochemistry for the vascular and neuronal markers smooth-muscle actin (SMA), isolectin B4 (IB4), and calcitonin gene-related peptide (CGRP). Glutamate infusion resulted in a PBF increase that lasted for 60 s. Positive immunolabeling was observed for the three glutamate transporters, but was more pronounced for VGluT3. Moreover, VGluT3 immunoreactivity was observed within nerve fibers entering the dental pulp and terminating at the periphery and at the vicinity of odontoblasts. Also, VGluT3 was colocalized with the vascular marker SMA, and in some nerve fibers with IB4, but not with CGRP. This study provides support for a control of dental pulp microcirculation by neurons expressing VGluT3.
谷氨酸存在于支配牙髓的初级感觉传入神经中，已知其具有血管活性作用。本研究的目的是：（i）评估向牙髓中注入谷氨酸后牙髓血流量（PBF）；（ii）观察表达谷氨酸囊泡转运体（VGluT）的谷氨酸能神经纤维的分布。在向牙髓注入谷氨酸（0.5 M）与注入生理盐水前后，用激光多普勒血流仪监测PBF。除了对血管和神经元标志物平滑肌肌动蛋白（SMA）、异凝集素B4（IB4）和降钙素基因相关肽（CGRP）进行免疫化学检测外，还对VGluT1、2和3进行了免疫化学检测。注入谷氨酸导致PBF增加，持续60秒。观察到三种谷氨酸转运体均有阳性免疫标记，但VGluT3更为明显。此外，在进入牙髓并终止于周边和成牙本质细胞附近的神经纤维中观察到了VGluT3免疫反应性。而且，VGluT3与血管标志物SMA共定位，在一些神经纤维中与IB4共定位，但不与CGRP共定位。本研究为表达VGluT3的神经元对牙髓微循环的调控提供了支持。
