Changes in expression of peptides in rat facial motoneurons after facial nerve crushing and resection

Abstract

In situ hybridization histochemistry was used to study changes in mRNAs coding neuropeptides such as α-calcitonin gene-related peptide (CGRP), β-CGRP, cholecystokinin (CCK) and galanin, in rat facial motoneurons following axotomy of the facial nerve. In control rats, 38%, 55% and 7% of the facial motoneurons expressed α-CGRP, β-CGRP and CCK mRNAs, respectively. No galanin mRNA-containing motoneurons were observed in these animals. The levels of mRNA for α-CGRP, CCK and galanin were increased while the β-CGRP mRNA level was decreased after axotomy. The levels of mRNAs for these peptides returned to the control values by 2–4 weeks after nerve crush, whereas nerve resection had more prolonged effects. Within 3–4 weeks after injury, nerve resection had greater effects of β-CGRP, CCK and galanin mRNAs than did nerve crush. Thus, there appear to be differences in the regulation of mRNA expression of these peptides in axotomized motoneurons.