title: A dynorphinergic pathway of Leu-enkephalin production in rat substantia nigra.
abstract: The amino acid sequence of the opioid peptide Leu-enkephalin is found within several larger peptides, which are generated from the precursors proenkephalin and prodynorphin. Proenkephalin contains four copies of the sequence of Met-enkephalin, a single copy of the sequence of Leu-enkephalin and one copy each of two extended Met-enkephalin sequences. Proenkephalin contains three peptides--alpha-neo-endorphin, dynorphin A and dynorphin B--the N-terminal sequences of which are identical to that of Leu-enkephalin. There is good evidence that the large amounts of Leu-enkephalin found in the adrenal medulla are generated from the precursor proenkephalin, but as yet prodynorphin has not been shown to be processed to yield Leu-enkephalin. We show here that the relatively high levels of Leu-enkephalin found in the rat substantia nigra are supplied by striatonigral axons and generated from the precursor prodynorphin.
mesh_terms: D000818:Animals; D002421:Caudate Nucleus / Q000378:metabolism; D004743:Enkephalin, Leucine / Q000096:biosynthesis*; D004745:Enkephalins / Q000378:metabolism*; D011498:Protein Precursors / Q000378:metabolism*; D051381:Rats; D013378:Substantia Nigra / Q000378:metabolism*
chemical_list: D004745:Enkephalins; D011498:Protein Precursors; D004743:Enkephalin, Leucine; C033660:preproenkephalin