Abstract
1. Acid extracts from pedal ganglia of Mytilus edulis was fractionated by high-pressure liquid chromatography (HPLC). 2. Components were recovered which had the same retention times as met- and leu-enkephalin. 3. When tested in an in vitro assay, these components inhibited dopamine-stimulated adenylate cyclase activity in a naloxone-reversible manner. 4. These results suggest that molluscan neural tissue contains opioid peptides similar, perhaps identical, to the mammalian enkephalins.