DISTRIBUTION OF DIACYLGLYCEROL LIPASE ALPHA, AN ENDOCANNABINOID SYNTHESIZING ENZYME, IN THE RAT FOREBRAIN

1,2-diacylglycerol lipase alpha (DAGL alpha) is responsible for the biosynthesis and release of 2-arachidonoyl-glycerol (2-AG), the most abundant endocannabinoid in the brain. Although its expression has been detected in discrete regions, we showed here an integrated description of the distribution of DAGL alpha mRNA and protein in the rat forebrain using in situ hybridization histochemistry and immunohistochemistry. As novelty, we described the distribution of DAGL alpha protein expression in the olfactory system, the rostral migratory stream, neocortex, septum, thalamus, and hypothalamus. Similar DAGL alpha immunostaining pattern was also found in the brain of wild-type, but not of DAGL alpha knockout mice. lmmunohistochemical data were correlated by the identification of DAGL alpha mRNA expression, for instance, in the somata of specific cells in olfactory structures, rostral migratory stream and neocortex, cells in some septal-basal-amygdaloid areas and the medial habenula, and magnocellular cells of the paraventricular hypothalamic nucleus. This widespread neuronal distribution of DAGL alpha is consistent with multiple roles for endocannabinoids in synaptic plasticity, including presynaptic inhibition of neurotransmitter release. We discuss our comparative analysis of the forebrain expression patterns of DAGL alpha and other components of the endocannabinoid signaling system, including the CB1 receptor, monoacylglyceride lipase (MAGL), and fatty acid amide hydrolase (FAAH), providing some insight into the potential physiological and behavioral roles of this system. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved.