Synthesis of a specific oligodeoxyribonucleotide probe and its use for studying proenkephalin A gene expression

A 44-mer, complementary to the coding region of bovine adrenal medullary proenkephalin A mRNA (ProEnkA mRNA) has been synthesized as a specific probe for this mRNA. Northern-blot hybridization analysis identified a single band in an RNA extract from bovine, ovine and porcine adrenal medullae. The molecular size of these hybridized bands (1400-1600 nucleotides) was in excellent agreement with that reported previously using cloned cDNA probes. In situ hybridization on bovine and ovine adrenal sections revealed that ProEnkA mRNA was localized selectively in cells at the outer margin of the medulla, a region rich in adrenaline-containing cells. This study both confirms and extends previous findings with cloned cDNA probes on the presence of high concentrations of ProEnkA mRNA in cells at the periphery of the adrenal medulla. In addition, it demonstrates the usefulness of synthetic oligodeoxyribonucleotides as specific and sensitive probes for the study of proenkephalin A gene expression.