NO-cGMP Signaling in Endothelial Function of the Healthy and Inflamed Dental Pulp

The intra- and intercellular signaling molecule nitric oxide (NO) is produced in endothelial cells by the activity of endothelial NO synthase (eNOS). Upon formation, NO diffuses into the underlying vascular smooth muscle cells, where it activates NO-sensitive guanylyl cyclase (NO-GC) resulting in the production of cyclic guanosine 3',5'-monophosphate (cGMP) from guanosine 5'-triphosphate (GTP). Inducing vasodilatation, inhibiting platelet aggregation and leukocyte adhesion, and inhibiting the proliferation and migration of vascular smooth muscle cells, the NO-cGMP signaling leads to a number of anti-inflammatory processes. Inflammation-dependent elevated concentrations of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in blood vessels of inflamed dental pulp induce an uncoupling of eNOS and oxidized NO-GC, leading to a disruption of NO-cGMP signaling. Endothelial dysfunction in inflamed dental pulp alters cell-cell and cell-matrix interactions, reducing the regenerative and reparative potential of the dentin-pulp complex in response to carious lesions. In the therapeutic management of caries, it is essential to consider the presence of endothelial dysfunction in the inflamed dental pulp. The utilization of NO-GC stimulators and activators in indirect and direct pulp capping materials may enhance the regeneration and repair potential of inflamed dental pulp.