A sesquiterpene-rich essential oil from Cannabis sativa L. attenuates symptoms and neuroinflammation in experimental autoimmune encephalomyelitis model through a CB2-mediated signalling

Background: The efficacy of cannabinoid-based medication as analgesic and neuroprotective in multiple sclerosis (MS) has been described, but little is known on other cannabis active compounds, such as terpenes. Purpose: To investigate the therapeutic potential and molecular mechanism of non-psychotropic Cannabis sativa L. essential oil (EO) in an animal model of MS. Methods: Chemical composition of EO was analyzed using GC-MS and GC-FID. Mouse model of experimental autoimmune encephalomyelitis (EAE) was employed to evaluate EO efficacy on pain (hot and cold plate test, von Frey test), motor disability (clinical score, rotarod), emotional alterations (sucrose splash test, tail suspension test, open field, light-dark box test) (n = 11). Tissues and LPS-stimulated BV2 cells were analyzed by Western blot, immunofluorescence, Luxol Fast Blue (LFB), hematoxylin and eosin (H&E) staining, UHPLCHRMS analysis. Results: β-caryophyllene, α-humulene, and caryophyllene oxide were the most abundant EO constituents. Intranasal administration of EO attenuated thermal and mechanical hypersensitivity, promoted motor function recovery, and induced antidepressant- and anxiolytic-like effects in EAE mice. EO increased LFB staining and MBP content while reducing H&E staining. In spinal cord and hippocampal tissues, EO reduced proinflammatory microglia (CD11b/IBA-1 ratio), restored the IL-17/IL-10 balance, and promoted a shift of microglia toward an anti-inflammatory phenotype by increasing CD206 and FoxP3 expression. Mechanistically, EO markedly upregulated CB2 receptor expression in both EAE mice and LPS-stimulated BV2 cells. The protective effect of EO was abolished by a CB2 antagonist (AM630) but not by CB1 blockade (AM251). Conclusion: Intranasal EO alleviates EAE symptoms and comorbidities through a CB2-mediated attenuation of neuroinflammation and demyelination.