Identification of receptors and enzymes for endocannabinoids in NSC-34 cells: relevance for in vitro studies with cannabinoids in motor neuron diseases

Abstract

NSC-34 cells, a hybridoma cell line derived from the fusion of neuroblastoma cells with mice spinal cord cells, have been widely used as an in vitro model for the study of motor neuron diseases [i.e. amyotrophic lateral sclerosis (ALS)]. In the present study, they were used to characterize different elements of the cannabinoid signaling system, which have been reported to serve as targets for the neuroprotective action of different natural and synthetic cannabinoid compounds. Using RT-PCR, Western blotting and immunocytochemistry, we first identified the presence of the cannabinoid CB(1) receptor in these cells. As expected, CB(2) receptor is not expressed in this neuronal cell line, a result that is concordant with the idea that this receptor type is preferentially expressed in glial elements. Diacylglycerol-lipase (DAGL) and N-arachidonoylphosphatidylethanolamine-phospholipase D (NAPE-PLD), the enzymes that synthesize endocannabinoids, have also been detected in these cells using RT-PCR, and the same happened with the endocannabinoid-degrading enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol-lipase (MAGL). The presence of the CB(1) receptor in these cells supports the idea that this receptor may play a role in the regulation of cellular survival face to excitotoxic injury. Interestingly, the expression of CB(1) receptor (and also the FAAH enzyme) was strongly up-regulated after differentiation of these cells, as previously reported with glutamate receptors. No changes were found for NAPE-PLD, DAGL and MAGL. Assuming that glutamate toxicity is one of the major causes of neuronal damage in ALS and other motor neurons diseases, the differentiated NSC-34 cells might serve as a useful model for studying neuroprotection with cannabinoids in conditions of excitotoxic injury, mitochondrial malfunctioning and oxidative stress.