Psychopharmacological effects of Morinda lucida BENTH leaf aqueous extract in Balb/C mice in a model of LPS-induced neuroinflammation

Background: The cost and irreversibility of Alzheimer's disease make its management difficult. To find alternative and rational solutions, our communities resort to the use of medicinal plants “Morinda lucida BENTH” (M.l BENTH). In the Republic of Congo, there are no studies highlighting the effects of Morinda lucida BENTH on the central nervous system. Objective: to research the effects of the aqueous extract of Morinda lucida BENTH leaves on the behavior and memory of Balb/C mice. Methods: The extraction of fresh leaves of Morinda lucida BENTH was done by maceration. We carried out an experimental study in Balb/C mice. They were treated per os orally with different concentrations of this extract (200 mg/kg and 400 mg/kg) “group D and E” then intraperitoneally with LPS while distilled water 10 ml/kg “group A” was used as negative control, distilled water associated with LPS “group B” and Donepezil 5 mg/kg “group C” as positive controls. Results: Analysis of the effects of M.l BENTH on the behavior of Balb/C mice showed that the aqueous extract of M.L BENTH leaves at doses of 200 and 400 mg/Kg did not influence (p>0.05) the behavior of Balb/C mice compared to controls in the open field test; however, in the cross maze test, the aqueous extract of M.l BENTH leaves at a dose of 200 mg/Kg significantly reduced NEPC : number of entries in the central part (*p<0.01), NEBO : number of entries in the open arms (*p<0.02), NEBF: number of entries in the closed arms (***p<0.007); moreover, at a dose of 400 mg/Kg this difference was recorded only for NEPC : (*p<0.05) compared to controls. The evaluation of the effects of M.l BENTH on memory showed a significance of the aqueous extract of M.l BENTH leaves at the dose of 200mg/Kg for the TEOF: time to explore familiar objects (*p<0.02), compared to the controls in the object recognition test. A significant difference was also observed between the aqueous extract of M.l BENTH leaves at the dose of 200mg/Kg (*p<0.02), Donepezil 5mg/Kg (Aricept*) at the dose of 5mg/kg (*p<0.03) for the NECC : number of entries in the target quadrant in the Morris test. Conclusion: The aqueous extract of M.l BENTH leaves would have beneficial effects on behavior and memory. It is therefore possible that at a certain dose (200mg/Kg), M.l BENTH has anxiolytic properties, confirming its use in traditional medicine.