Beta-caryophyllene, a CB2R selective agonist, protects against cognitive impairment caused by neuro-inflammation and not in dementia due to ageing induced by mitochondrial dysfunction

Background: Dementia is a neurodegenerative disorder majorly evidenced by cognitive impairment. Although there are many types of dementia, the common underlying etiological factors in all the types are neuro-inflammation or ageing induced apoptosis. β-caryophyllene, a cannabinoid type-2 receptor agonist has reported to have promising neuroprotective effects in cerebral ischemia and neuro-inflammation. Objective: In the present study, we evaluated the effects of β-caryophyllene, against animal models of dementia whose etiology mimicked neuro-inflammation and ageing. Method: Two doses (50 and 100 mg/kg of body weight) of β-caryophyllene given orally were tested against AlCl3-induced dementia in male Sprague Dawley (SD) rats using Morris water maze test. Subsequently, the effect of the drug was assessed for episodic memory in female SD rats using novel object recognition task in doxorubicin-induced neuro-inflammation and male SD rats for chemobrain model. Moreover, its effects were evaluated in D-galactose-induced mitochondrial dysfunction leading to dementia. Results: β-caryophyllene, at both the doses, showed significant improvement in memory when assessed using parameters like target quadrant entries, escape latency and path efficiency in Morris water maze test for spatial memory. In the doxorubicin-induced chemobrain model, β-caryophyllene at 100 mg/kg significantly elevated acetylcholinesterase and catalase levels and lowered lipid peroxidation compared to the disease control. In the novel object recognition task, β-caryophyllene at 100 mg/kg significantly improved recognition index and discrimination index in the treated animals compared to the disease control, with a significant increase in catalase and decrease in lipid peroxidation in both hippocampus and frontal cortex. However, in D-galactose-induced mitochondrial dysfunction model, β-caryophyllene failed to show positive effects when spatial memory was assessed. It also failed to improve D-galactose induced diminished mitochondrial complex I and II activities. Conclusion: Hence, we conclude that β-caryophyllene at 100 mg/kg protects against dementia induced by neuro-inflammation with no effect on neuronal aging induced by mitochondrial dysfunction.