IMMUNOCYTOCHEMICAL LOCALIZATION OF ENDOGENOUS CODEINE AND MORPHINE

Experiments carried out by indirect immunofluorescence and unlabelled antibody enzyme procedures revealed the presence of morphine-like immu noreactive material in the perikarya, fibers, and terminals of neurons in different, discrete areas of rat and human brain. The monoclonal a nd polyclonal anti-morphine antibodies used do not distinguish between morphine and codeine. Endogenous morphine seems to be stored in neuro ns as the 3-ethereal sulphate conjugate. This possibility is supported by the finding that, although active uptake of [H-3]morphine has not been detected in brain synaptosomes, long-term i.c.v. injection of the tritiated opiate results in the accumulation of radioactivity inside the same neurons in which the endogenous alkaloids have been detected. Finally, striatal slices exposed to high K+ concentrations showed a r apid disappearance of the morphine-like immunoreactive material from n eurons, indicating that endogenous alkaloids are released from neurons by depolarization.