Biphasic increase of calcitonin gene-related peptide-like immunoreactivity in rat hypoglossal motoneurons after nerve transection.

In the hypoglossal system the regulation of calcitonin gene-related peptide (CGRP) following peripheral nerve transection and prevention of reinnervation was studied using immunocytochemistry. In the adult rat axotomy resulted in a biphasic increase of CGRP-immunoreactivity (IR) with a first peak after 2 days and a second peak after 18 days. In addition to an increase in staining intensity the number of CGRP-IR motoneurons was also increased. The lesion-induced alterations of CGRP-expression in the hypoglossal nucleus correspond to those described in other motor system. A possible contribution of CGRP to degeneration/regeneration processes is discussed.