FATTY-ACID AMIDE HYDROLASE IS LOCATED PREFERENTIALLY IN LARGE NEURONSIN THE RAT CENTRAL-NERVOUS-SYSTEM AS REVEALED BY IMMUNOHISTOCHEMISTRY

The distribution in the rat brain of fatty acid amide hydrolase (FAAH) an enzyme that catalyzes the hydrolysis of the endogenous cannabinoid anandamide was studied by immunohistochemistry. An immunopurified, po lyclonal antibody to the C terminal region of FAAH was used in these s tudies. The large principal neurons, such as pyramidal cells in the ce rebral cortex, the pyramidal cells the hippocampus, Purkinje cells in the cerebellar cortex and the mitral cells in the olfactory bulb, show ed the strongest FAAH immunoreactivity. These FAAH-containing principa l neurons except the mitral cells in the olfactory bulb are in close p roximity with cannabinoid CB1 receptors as revealed by our previous im munohistochemical study. Moderately or lightly stained FAAH-containing neurons were also found in the amygdala, the basal ganglia, the deep cerebellar nuclei, the ventral posterior nuclei of the thalamus, the o ptic layer and the intermediate white layer of the superior colliculus and the red nucleus in the midbrain, and motor neurons of the spinal cord. These data demonstrate that FAAH is heterogeneously distributed and this distribution exhibits considerable, although not complete, ov erlap with the distribution of cannabinoid CBI receptors in rat brain. (C) 1998 Elsevier Science Ireland Ltd, All rights reserved.