An enkephalin-like molecule in earthworm coelomic fluid modifies leukocyte behavior

Substances that were immunoreactive in an RIA specific for met-enkephalin were detected following HPLC fractionation of earthworm coelomic fluid. Earthworm coelomocytes and human granulocytes were analyzed for changes in conformation based on measurements of cellular area and perimeter and expressed mathematically by using the Form Factor (FF). For coelomocytes the FF decreased following exposure to DAMA, a synthetic enkephalin analogue (D-Ala2, Met5-enkephalinamide). DAMA stimulated migration whereas untreated cells and those exposed to the specific opiate blocker naloxone did not move. The enkephalin-like molecule when exposed to human granulocytes stimulated an increased number of activated cells. Our results suggest a relationship between the immune and nervous systems of earthworms.