CGRP in peripherally axotomized mesencephalic trigeminal neurones of the rat

Immunoreactivities for substance P (SP-ir) and calcitonin gene-related peptide (CGRP-ir) were examined in neurones in the mesencephalic trigeminal tract nucleus of nerve-injured rats. One week following unilateral transection of the trigeminal root, the masseteric nerve (MN) or the inferior alveolar nerve (IAN), CGRP-ir but not SP-ir was detected in these neurones bilaterally with ipsilateral dominance. Most of the CGRP-ir (immunoreactive) neurones were retrogradely labelled when fluorogold (FG) had been applied to the proximal stump of the MN or the IAN. Sham surgery including insult to the masseter muscle induced CGRP-ir while skin incision did not.