DETECTION OF THE MESSENGER-RNA CODING FOR ENKEPHALIN PRECURSOR IN THE RAT-BRAIN AND ADRENAL BY USING AN INSITU HYBRIDIZATION PROCEDURE

The messenger RNA coding for preproenkephalin A (PPA) has been detected in tissue sections of the rat brain and adrenal by using two rat PPA cDNA labeled with 32P or 35S as probes. In the brain, neurons were labeled in areas known to correspond to sites of synthesis of enkephalins, including the caudate-putamen, the nucleus accumbens, the olfactory cortex, the hypothalamus, the brainstem and the granular layer of the cerebellum. The presence of the PPA and mRNA in the normal rat adrenal medulla shows transcription of the PPA gene in such cells despite the absence of enkephalin immunoreactivity in them. These results demonstrate in situ hybridization as an efficient technique to detect the sites of synthesis of PPA.