Glutamate control of pulpal blood flow in the incisor dental pulp of the rat

Abstract

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.

Nitric Oxide in Dental Pulp Tissue: From Molecular Understanding to Clinical Application in Regenerative Endodontic Procedures

“…82 Moreover, previous studies have identified the effective regulation of neurons on dental pulp microcirculation under physiological and pathological conditions. 83,84 Similarly, eNOS-mediated pulp vasodilation is also a valuable response in neurogenic inflammation and involves subsequent release of NO produced in endothelial cells and of inflammatory mediators (e.g., substance P) from sensory nerve endings. 85,86 Angiogenesis, another critical physiological event associated with wound healing and tissue regeneration, involves complex cellular activities correlated with cell proliferation and migration.…”

Dental Tissue Engineering by Neural Differentiation of Dental Stem Cells and Nano-systems: A Review

“…In addition to neuropeptides secreted by sensory nerves, glutamate can regulate blood flow in vasodilation. Glutamate transporter-expressing neurons release glutamate into the pulp [69], which binds to the pulp's metabotropic glutamate receptors (GluRs), which regulate pulp blood flow [70].…”

A New Player in the Hippocampus: A Review on VGLUT3+ Neurons and Their Role in the Regulation of Hippocampal Activity and Behaviour

“…However, VGLUT3 mRNA-positive somas were not detected in the spinal cord [ 31 ]. Interestingly, in rat, pulpal blood flow was regulated by VGLUT3+ nerve terminals [ 33 ], suggesting the possibility of an even more peripheral projection. Moreover, VGLUT3 immunoreactivity was detected in the heart, liver, and kidney but not in intestinal or lung tissue [ 34 ].…”