Induction of Heat Shock Protein 70 after Experimental Pulpal Exposure in Rats / 대한마취과학회지

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.

Ultrastructural analysis of glutamate immunoreactive primary afferent terminals in the trigeminal nucleus principalis and trigeminal nucleus oralis of the rat / 대한해부학회지

The present study was aimed to investigate the ultrastructure of the primary afferent terminals and whether glutamate may be a transmitter in these terminals within the trigeminal nucleus principalis and oralis of the rat. Labeling of primary afferent terminals was performed by the injection of the CTB-HRP into the trigeminal ganglion. Ultrastructural analysis and assessment of the glutamate like immunoreactivity by the immunogold technique was performed with the 66 peroxidased labeled boutons in the nucleus principalis and 62 in the nucleus oralis. Labeled boutons were presynaptic to dendritic shafts of the secondary neurons and postsynaptic to the pleomorphic vesicles containing endings (p-endings). Most of the labeled boutons made synaptic contact with the dendritic shafts. A little labeled boutons in the nucleus oralis but no in the nucleus principalis was observed to make synaptic contact with the soma or proximal dendrite. Most of the labeled boutons made synaptic contact with one to three neurofiles, but labeled boutons showing complex synaptic connections, such as those with five or more neurofiles, were more in principalis than in oralis. The average diameter of p-endings were smaller than that of labeled boutons (p<0.05). The diameter of the postsynaptic dendritic shafts were smaller in nucleus principalis than in nucleus oralis, thus indicated that the labeled boutons made synaptic contact with more distal portion of the postsynaptic dendrite in the nucleus principalis than in the nucleus oralis. The gold particle density over the labeled boutons were significantly higher than that over the p-endings and average tissue particle density. They were ranged from 110 to 430% of the average tissue particle density. These findings indicate that synaptic connection of the primary afferent terminals is organized in different manner in nucleus principalis and oralis, and suggest that glutamate is involved as neuroactive substance in the primary afferent terminals of the trigeminal system.