Neuritogenic Effects of Cannabinoids with Nerve Growth Factor (NGF) on PC12 Cells
Cannabis (Cannabis sativa) commonly known as marijuana has been used for a variety of recreational, religious, and medicinal purposes across diverse cultures. Cannabinoids, the major terpenophenolic psychoactive constituents of cannabis, have shown a broad spectrum of pharmacological effects and potential for treatment of chronic pain and neurological diseases. Recent reports have emphasized the role of the cannabinoid system, including cannabinoid receptors and endocannabinoids, in neuroprotection and stimulation of neurogenesis. The neurotropic and neuritogenic potential of cannabinoids were investigated in vitro on PC-12 cells, a cell line derived from a pheochromocytoma of the rat adrenal medulla. PC12 cells stop dividing and terminally differentiate when treated with neurotrophins like Nerve Growth Factor (NGF). This makes PC12 cells useful as a model system for neuronal differentiation. NeuroScreen 1 (NS-1), a sub-clone of PC12 cells with high sensitivity to neuritogenic effects of NGF, was employed in this study. The effects of cannabinoids on neuritic outgrowth in NS-1 cells were evaluated alone and in the presence of suboptimal concentrations of NGF. Quantification of neuritogenesis was performed by analysis of digital cell images for average numbers of neuritis/cells, neuritic nodes/cell and average length of the neurites. Several cannabinoids namely, Δ9-tetrahydrocannabinol (Δ9-THC), Δ8-tetrahydrocannabinol (Δ8-THC), cannabinol (CBN), cannabigerol (CBG), tetrahydrocannabivarin (THCV), cannabigerolic Acid (CBGA) and and non-cannabinoid cannabis constituent canniflavin-A were tested. The cannabinoids namely, Δ9-THC (1), CBN (2) and a non-cannabinoid canniflavin-A (3) significantly induced NGF-stimulated neuritic outgrowth in the NS-1 cells. Canniflavin-A was observed to be the most potent among the compounds tested. Understanding the mechanism for neurotrophic action of these compounds and identification of target signal transduction pathways shall be important in their further evaluation as potential neurotrophic agents and their potential application in treatment of neurodegenerative diseases.
Acknowledgements: The authors gratefully acknowledge funding support from NCNPR & USDA-ARS Cooperative Scientific Agreement No. 58 – 6408 – 02 – 1-612. References:  Hill, et al. (2012), Pharmacol & Therapeutics, 133: 79 – 97.  Kreitzer, Stella (2009) Pharmacology & Therapeutics, 122: 83 – 96.