Distribution of glutamate receptor, ionotropic, kainate 1 and neuropeptide calcitonin gene-related peptide mRNAs during formation of the embryonic and postnatal mouse molar in the maxilla

Abstract

The neuropeptide calcitonin gene-related peptide (CGRP) is a well-characterized neurotransmitter. Glutamate receptor, ionotropic, kainate 1 (Grik1) has also been demonstrated to generate high-affinity kainate receptors. However, little is known about the roles of CGRP and Grik1 during the developmental formation of teeth. In this study, we endeavoured to analyse the expression and localization of CGRP and Grik1 mRNAs using in situ hybridization on the mouse maxilla during development from the embryonic stage (E18.5) to after birth (P10, P15 and P20). We found that hybridization with an anti-sense probe for CGRP clearly localized in the maxilla at E18.5 in contrast to that of P15 and P20. Hybridization with an anti-sense probe for CGRP was not detected in the dental pulp of molars in the maxilla at P10, which is in contrast to Grik1 mRNA at the same developmental stage. Hybridization with an anti-sense probe for Grik1 mRNA was detected in the basal region of the dental pulp of molars at P10 and P15. Finally, these markers were not detected in molars in the mouse maxilla at P20. The ratio of positive cells for the hybridization signals of Grik1and CGRP in the dental pulp decreased from E18.5 (p<0.001). These features in CGRP and Grik1r mRNAs may indicate roles of function during tooth development between embryonic and postnatal stages with root formation and erupted movements.