Endogenous morphine levels increase in molluscan neural and immune tissuesafter physical trauma

The aim of this study was to demonstrate by biochemical and immunocytochemi cal methods the presence of endogenous morphine in nervous and immune tissu es of the freshwater snail, Planorbarius corneus. High performance liquid c hromatography (HPLC) coupled to electrochemical detection performed on tiss ues from control snails, revealed that the CNS contains 6.20 +/- 2.0 pmol/g of the alkaloid, the foot tissue contains a much lower level, 0.30 +/- 0.0 3 pmol/g, whilst morphine is not detected in the hemolymph and hepatopancre as. In specimens that were traumatized, we detected a significant rise of t he CNS morphine level 24 h later (43.7 +/- 5.2 pmol/g) and an initial decre ase after 48 h (19.3 +/- 4.6 pmol/g). At the same times, we found the appea rance of the opiate in the hemolymph (0.38 +/- 0.04 pmol/ml and 0.12 +/- 0. 03 pmol/ml) but not in the hepatopancreas, Using indirect immunocytochemist ry, a morphine-like molecule was localized to a number of neurons and a typ e of glial cell in the CNS, to some immunocytes in the hemolymph and to amo ebocytes in the foot, as well as to fibers in the aorta wall. Simultaneousl y to the rise of morphine biochemical level following trauma, morphine-like immunoreactivity (MLR) increased in both intensity and the number of struc tures responding positively, i.e., neurons and fiber terminals. In another mollusc, the mussel Mytilus galloprovincialis, the same pattern of enhanced MIR was found after trauma. Taken together, the data suggest the presence of a morphinergic signaling in invertebrate neural and immune processes res embling those of classical messenger systems and an involvement in trauma r esponse. (C) 1999 Elsevier Science B.V. All rights reserved.