ABSTRACT
BACKGROUND: Inducible heat shock protein 70s (iHSP70) are expressed by stressful stimuli that result in protein denaturation, and are thought to assist in the maintenance of cellular integrity and viability. In addition, iHSP70 is known to be a sensitive marker of neuronal injury. To my best knowledge, no previous studies have been documented on iHSP70 induction by nociceptive impulse transmission through peripheral nerves not by direct neural damage. The purpose of this study was to examine the hypothesis that iHSP70 can be expressed in the nervous system, which is related to the dental nociceptive pathway, by tooth pulp inflammation. METHODS: The pulp of rat mandibular molars was exposed. Animals were sacrificed at 1, 4, and 7 days after pulpal exposure, and the pulps were evaluated histologically. Also, iHSP70 levels were examined in the Gasserian ganglion (GG) and the trigeminal sensory nucleus (TSN). RESULTS: At 4 days after pulpal exposure, iHSP70 was significantly more expressed in the ipsilateral GG than in the contralateral GG. In the histological study, inflammation was found in the entire pulp tissue at 4 days. There were no significant differences in iHSP70 levels between the ipsilateral TSN and the contralateral TSN. Also, there were no significant differences in iHSP70 expression of GG and TSN between both sides at 1 and 7 days after pulpal exposure. CONCLUSIONS: These results suggest that iHSP70 can be expressed in the GG at 4 days after pulpal exposure by nociceptive impulses due to pulpal inflammation.