Localization of beta pre-protachykinin mRNA in nodose ganglion

The neurons which synthesize tachykinins in the capsaicin-sensitive afferent nerves of the respiratory tract are largely localized to the nodose ganglia. Using a radiolabelled antisense cRNA probe constructed from cDNA for the major precursor of substance P and neurokinin A (beta-preprotachykinin: beta-PPT), we have localized specific mRNA for this peptide in neurons of the nodose ganglion of rat using in situ hybridization. 26% of neurons gave a positive hybridization signal, which was in agreement with the same proportion of cell bodies showing substance P-like immunoreactivity. The specificity of the hybridization was confirmed by the absence of labelling using RNase pre-treatment and a sense probe having the same sequence as beta-PPT mRNA. This approach may now allow the investigation of factors which regulate synthesis of tachykinins at a gene transcriptional level.