Györfi A

Role of histamine in the development of neurogenic inflammation of rat oral mucosa

The mechanism of development of neurogenic inflammatory reaction induced by the topical application of capsaicin was studied in the oral mucosa of rats with or without histamine antagonist pretreatment.The existence of a cholinergic component of the vasodilation was investigated using a muscarinic receptor antagonist.Results indicated that the neurogenic inflammatory increases in vascular permeability and blood flow are mediated in part by H1-receptors. H2-receptors and cholinergic pathways are apparently not activated in these processes.

Venodilatory Effect of Vascular Endothelial Growth Factor on Rat Gingiva

BACKGROUND Endothelial cell proliferation, angiogenesis, and increased vascular permeability are among the effects of vascular endothelial growth factor (VEGF) in various organs. However, the effects of VEGF on gingival hemodynamics, especially on venules, have not been thoroughly investigated. This study investigated the acute circulatory effects of VEGF on rat gingival venules. METHODS Fifty-six anesthetized rats were divided into five study groups; each rat received 10 microl of experimental solution dripped onto the lower interincisal gingiva. The groups included: 1) saline control (after the experiment, gingiva was excised for VEGF receptor 2 [VEGFR2] immunohistochemistry); 2) VEGF (0.1, 1, 10, or 50 microg/ml); 3) VEGF2 receptor antagonist 5-((7-benzyloxyquinazolin-4-yl)amino)-4-fluoro-2-methyl-phenol-hydrochloride (ZM323881; 20 microg/ml); 4) ZM323881 (20 microg/ml) followed by VEGF application (50 microg/ml after 15 minutes); and 5) VEGF (10 microg/ml), these rats were premedicated with nitric oxide (NO) synthase blocker (N(G)-nitro-L-arginine-methyl-ester [L-NAME]; 1 mg/ml in drinking water) for 1 week before the experiment. Changes in gingival superficial venule diameter were measured by vital microscopy prior to and 1, 5, 15, 30, and 60 minutes after the administration of the experimental solutions. RESULTS VEGF dose-dependently increased the venular diameter compared to saline. ZM323881 alone did not cause any alteration. Premedication with ZM323881 or L-NAME decreased the dilatory effects of VEGF. VEGFR2 immunohistochemical labeling was observed in the wall of the venules. CONCLUSIONS There is no remarkable VEGF production under physiologic circumstances in rat gingiva, but VEGF is able to increase gingival blood flow through the activation of VEGF2 receptors. Furthermore, NO release may contribute to VEGFs vasodilatory effect.

Effect of denervation on the neurogenic inflammation of the rat mandibular mucosa

SummaryEffects of local exposure to capsaicin on the vascular permeability and blood flow were studied in the rat oral mucosa at days 2 and 14 after the unilateral transcection of the inferior alveolar nerve (IAN). The distribution of nerve fibers displaying substance P (SP) and calcitonin gene-related peptide (CGRP) immunoreactivity (IR) in the mandibular mucosa was also assessed.While the capsaicin-induced augmentation in vascular permeability was about 50% (P < 0.05) higher on the intact side (at both days 2 and 14) than on the denervated side, no difference in blood flow elevation was seen between the two sides. Transection of IAN caused only a slight reduction in the density of SP- and CGRP-IR fibers in the mucosa.It is concluded that in addition to the IAN fibers the mandibular mucosa examined also seems to be supplied by other sensory fibers. The presence of accessory trigeminal branches was also supported by immunohistochemical studies.