Tissue-selective inflammation in the oral cavity of the rat

Abstract

In the current study, carrageenan (CG; 100-1000 μg/site) was injected intraorally in the cheeks of Holtzman or Wistar rats to evaluate the consequences of administration of a non-immunogenic stimulus in the orofacial region. Subsequent inflammation was measured as oedema (increased thickness of the cheek wall using digital calipers), relative to the other cheek injected with saline. Oedema formation and tissue collection for histopathological studies were assessed at 0.5, 1, 2, 3, 4, 6, 24, 48, 72, 96, 120 and 144 h after injection. In parallel, other groups of rats were injected with CG in the hind paw, to provide a reference response. The inhibitor of prostaglandin biosynthesis, indomethacin, and antagonists of histamine, serotonin and NK1 receptors were injected s.c., 0.5 h before CG. CG induced a dose-related oedema more rapidly from 0 to 2 h which lasted for at least 72 h, showing a biphasic profile (peak at 2 and 24 h), compared with the monophasic oedema induced in rat paws (maximal duration of 24 h). Histopathological analysis of the CG-injected cheek revealed oedema formation with little leukocyte recruitment at 1-3 h, mast cell degranulation at 6 h, and a mixed polymorphonuclear and mononuclear cell infiltrate by 24 h. Histamine and serotonin antagonists and indomethacin, but not the NK1 antagonist, decreased cheek oedema in the first 4 h following carrageenan. Taken together, our data indicated important differences in the pattern of inflammation between the oral cavity and the paw which will determine the therapeutic approach to the treatment of inflammatory conditions in the oral cavity.

Actividad antiinflamatoria de psidium guineense SW en la mucosa bucal de ratas BIOU: Wistar

“…La presencia de abundante infiltrado inflamatorio mixto en los siguientes periodos de observación (24, 48 y 72 horas) indica la progresión de la respuesta inflamatoria a la fase celular, caracterizada por el movimiento de leucocitos, en particular neutrófilos de la circulación al sitio de la lesión. Adicionalmente, la densidad del tejido conectivo laxo refleja el aumento de permeabilidad capilar propio de la inflamación aguda 28,29, 30 .…”

“…Asimismo, en ese estudio, la inyección de formalina al 5% en el labio superior de ratas Sprague Dawley indujo signos histológicos de inflamación tisular, como degranulación de mastocitos y extravasación de granulocitos. En concordancia, Frade et al 30 en un estudio similar inyectaron intraoralmente carragenina en el carrillo de ratas Wistar y observaron 24 horas después gran cantidad de células mononucleares y polimorfonucleares.…”