Co-expression of alpha-CGRP and beta-CGRP mRNAs in the rat dorsal root ganglion cells

We examined the expression of alpha-calcitonin gene-related peptide (alpha-CGRP) and beta-CGRP mRNAs in the rat dorsal root ganglion (DRG) using in situ hybridization histochemistry with oligonucleotide probes. Analysis of autoradiograms showed that alpha-CGRP mRNA labeled 36.4% of all DRG neurons and beta-CGRP mRNA labeled 30.8%. Small and medium-sized neurons expressed both types of mRNA, but large neurons showed a predominance of alpha-CGRP mRNA expression. The colocalization of alpha-CGRP and beta-CGRP mRNAs was shown at a cellular level in consecutive DRG sections. Thus, we demonstrated that alpha-CGRP and beta-CGRP were distributed differently in the DRG neurons, although genes coding for these neuropeptides coexist in the small or medium-sized neurons.