CALCITONIN-GENE-RELATED PEPTIDE-IMMUNOREACTIVE (CGRP-IR) INTRADENTAL NERVES IN THE DOG

Calcitonin gene-related peptide (CGRP) is the most frequently occurrin g pepide in sensory neurons in the rat, Most of the Calcitonin Gene-Re lated Peptide Immunoreactive (CGRP-IP) nerves have been found to be Ca psaicin-sensitive suggesting an involvement in certain types of pain. In the dental pulp CGRP-IR nerve fibres have been studied in the rat, guinea pig, cat, sheep, pig, cow and horse but not in the dog. Extensi ve sprouting of CGRP-IP intradental nerves has been demonstrated in th e teeth with pulpal inflammation in rat molars. In the present investi gation the occurrence and distribution of CGRP-IR intradental nerves b oth in the normal and the injured and inflamed teeth of the dog was st udied. Immunolabelling was done by the Avidin-Biotin Complex (ABC) imm unoperoxidase technique, CGRP-IR intradental nerves were demonstrated in the dog. The pattern of distribution was found to be similar to tha t in other animal species, However, the tip one third of the coronal p ulp was sparsely innervated compared to that in the rat, Also much few er fibres were seen to penetrate predentine and dentine, and this appe ars characteristic of the dog teeth. Sprouting phenomenon seen in the rat was not found in the dog teeth. It is suggested that there might b e a species difference in the innervation pattern of CGRP-IR intradent al nerves between the rat molar and the dog canine and incisor teeth.