Reatividade vascular e celular da polpa dental de ratos frente a estímulos inflamatórios / Vascular and cellular responses to pro-inflammatory stimuli in rat dental pulp

RESUMO

The dental pulp is a soft, vascularized, and innervates tissue located in the core of a mineralised dental structure (enamel, dentin, and cement). This peculiar characteristic of being a tissue restrained inside a low compliance environment prompted us to study its vascular and cellular reactivity. Pro-inflammatory stimuli such as Substance P (SP), calcitonin-gene related peptide (CGRP), and prostaglandin E2 (PGE2) were applied to the exposed pulp of anaesthetised animals and the plasma extravasation measured by the Evans blue content. Leukocyte recruitment was evaluated morphometrically by counting the cell number present in serial sections of 13 4 µm-pulp tissue 6h after bacterial endotoxin (LPS; 0.06 - 1.2 µg/site) administration. Increase in pulp vascular permeability and cellular recruitment due to the injection of mentioned mediators in teh skin or LPS in the peritoneal cavity were used as positive controls. The local pulp application of SP, CGRP, and PGE2 significantly increased the vascular permeability, although in a minor dose range of that observed in the skin. In both tissues CGRP was the most potent mediator suggesting the presence of CGRP receptors, which was confirmed at least in the pulp, by the PCR method. In relation to cell recruitment it was necessary a higher dose (about 4-fold) of LPS to induce a similar pattern in the pulp as that observed in the rat peritoneal cavity suggesting a deficiency in adhesion molecules in blood vessels in the rat dental pulp. In addition, steroidal and non-steroidal anti-inflammatory drugs were able to reduce the cell recruitment showing the sensitivity of this method to study the effects of these two classes of drugs