The function of parvalbumin and calcitonin gene-related peptide in the inflamed pulp

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The tooth pulp in the normal rat contained parvalbumin-immunoreactive (ir) nerve fibers. In the root pulp, ir nerve fibers had a thick and smooth appearance. These nerve fibers projected to the coronal pulp, and made subodontoblastic nerve plexuses in the subodontoblastic layer. They sent their varicose terminals to the odontoblastic layer. An immunoelectron microscopic study revealed that parvalbumin-ir radicular axons were thick and myelinated. In the odontoblastic layer, ir neurites made close contact with cell bodies and processes of odontoblasts. At 1-3 days after the pulp exposure, the tooth pulp was devoid of parvalbumin ir nerve fibers. At 5-7 days, however, parvalbumin-ir pulpal nerve fibers increased in number and made nerve plexuses beneath the inflamed tissue. These nerve fibers mostly had a thin and varicose appearance. At 14 days after the pulp exposure, inflammatory cells were observed throughout the tooth pulp. Parvalbumin-ir nerve fibers decreased in number at this stage. They observed in the root pulp but not the coronal pulp. At 30-60 days, the abscess was formed at the root apex. Ir nerve fibers made plexuses around the abscess. A double immunofluorescence method demonstrated that the distribution patterns of parvalbumin- and calcitonin gene-related peptide (CGRP)-ir nerve fibers were similar at all stage. The present study suggests that parvalbumin and CGRP have an important role for the inflammation in the tooth pulp.