Cannabidiol and other non-psychotropic cannabinoids from Cannabis sativa as therapeutics for microglial-mediated neuroinflammation and neurodegeneration

Non-psychotropic phytocannabinoids produced by Cannabis sativa, including cannabidiol, cannabigerol, cannabichromene and their varin and acidic analogs, are emerging as promising modulators of neuroinflammation, particularly through actions on microglia, the brain's resident immune cells. These compounds engage numerous receptors, ion channels, and intracellular signaling systems in microglia associated with neuroinflammation, and therefore are promising therapeutic candidates to treat chronic microglial inflammation-mediated neurodegenerative disorders. Despite substantial public and scientific interest, comprehensive evaluation of their mechanistic diversity, disease-relevant potential, and translational gaps across neurodegenerative disorders remains limited. Commonly, gaps also exist between cannabis breeders' and cultivators' knowledge of phytocannabinoid diversity and translational scientists' understanding of therapeutic potential. In this review, we first provide an in-depth overview of the main non-psychotropic phytocannabinoids, their biosynthesis, and the genetics that control their production in cannabis. We then summarize the known mechanisms of action for each cannabinoid in microglial-expressed molecular targets and signaling pathways relevant to neuroinflammation. Lastly, we review the effects of non-psychotropic phytocannabinoids in pre-clinical models and clinical trials of four neuroinflammation-associated neurodegenerative diseases: Alzheimer's disease, Parkinson's disease, multiple sclerosis, and Huntington's disease. Current evidence supports meaningful biological activity and complex cannabinoid-specific polypharmacology, yet substantial gaps persist, especially for cannabinoids other than cannabidiol; addressing these gaps in disease-relevant models will be essential for translating these compounds into future therapeutic strategies. Further, we anticipate the summarized information will foster collaboration between cannabis breeders/cultivators and applications scientists for therapeutic evaluation and development of emerging non-psychotropic phytocannabinoids.