This proposal examines the properties of high threshold mechanoreceptors in the gingiva of the oral cavity. Teased fiber techniques will be used to record from single afferents of the inferior alveolar nerve of the goat. The oral cavity offers significant advantages over the other preparations for the study of mechanical nociception: 1) the dermatomal field is small, easing search techniques; 2) the gingiva is tightly attached and relatively incompressible, allowing for precise application of stimuli. Preliminary data indicated that the oral cavity may serve as a model of sensitization of mechanoreceptive afferents and aid in the understanding if the developmental of hyperalgesia. Sensitization of mechanoreceptors has rarely been observed. The current understanding of hyperalgesia is based primarily on the properties of thermo-responsive afferents, despite the fact that mechanical hyperalgesia is a fundamental symptom of traumatic injury. Perhaps for this reason, we understand little about the differential contribution of a wide spectrum of sensitizing agents. The present studies will compare response properties on inflamed and normal gingiva and assess the effects of a variety of algesics, including serotonin, histamine, bradykinin, prostaglandin E1 and E2, prostacyclin and hydroxy eixosatetranoic acids, in the development of sensitization in its various forms. Understanding the properties of mechanoreceptors in the development of hyperalgesia should lead to the development of more effective compounds for the prophylactic treatment of surgical trauma (including third molar removal) and may be useful in the treatment of gingivitis and periodontitis.
