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Background: The leaves of Olax subscorpioidea have become a mainstay in the management of inflammatory diseases and mental illness in folkloric medicine in Nigeria. Previous studies have shown its antidepressant and anti-inflammatory properties in experimental animals. Recently its antidepressant action was linked to the involvement of monoaminergic transmission. However, with accumulating evidences suggesting link between immuno-inflammatory signaling pathways and depression, there is dearth of information about its beneficial effect on inflammation associated depression. We thus evaluated the effect of n-butanol fraction of O. subscorpioidea leaves on lipopolysaccharide (LPS)-induced depressive-like behaviours and investigated its antidepressant effect with respect to its action on inflammatory and oxidative pathways. Methods: Fifty Swiss male mice were randomly assigned into five groups (n= 10): group 1 (vehicle only), group 2 (nBFOS 5mg/kg), group 3 (nBFOS 10 mg/kg), group 4 (imipramine 10 mg/kg), group 5 (vehicle). Mice were treated with vehicle or nBFOS (5 & 10 mg/kg) or imipramine intraperitoneal for seven days. Thirty minutes after treatment on day seven, animals were injected with LPS (0.83 mg/kg, i.p.) except group 1 (vehicle only). Twenty-four hours following LPS injection, animals were assessed for depressive symptoms using sucrose preference test and immobility using tail suspension test (TST). Brain levels of pro-inflammatory mediators interleukin-1β (IL-1β) and tumor necrosis factor (TNF), oxidative stress biomarkers (malondialdehyde and reduced glutathione) and plasma level of corticosterone were measured by Enzyme Linked immunosorbent assay. Results: LPS significantly (p < 0.05) increased immobility of mice in TST and decreased sucrose preference which is indicative of depressive-like behaviours. The depressive behaviours were significantly (p < 0.05) attenuated by nBFOS and imipramine compared to control. Furthermore, LPS-induced increase in malondialdehyde, corticosterone, TNF, IL-1β, and decrease in reduced glutathione, in the brain were significantly reversed by treatment with nBFOS and imipramine. Conclusion: The findings suggest that attenuation of LPS-induced depressive-like behaviours by the fraction of O. subscorpioidea leaves may be related to suppression of oxidative stress and inhibitory effect on inflammatory mediators in the central nervous system.

Introduction: Morin hydrate (MH) is a bioflavonoid component of many fruits and vegetables. Our previous research demonstrated that MH provides neuroprotection in mouse models of acute restraint stress and sleep deprivation by attenuating hippocampal neuronal damage and enhancing memory. Based on these findings, our study investigated the role of MH in chronic stress-induced neuronal and biochemical perturbations in BALB/c mice. Methods: Male BALB/c mice were divided into 6 groups (n=6). Groups 1 and 2 received vehicle (10 mL/kg normal saline), groups 3-5 received MH (5, 10, 20 mg/kg IP), while group 6 received ginseng (25 mg/kg) daily and 30 minutes afterward were restrained in a plastic cylindrical restrainer for 14 days. Results: Immobility time in the forced swim test increased in the MH-treated group, indicating an antidepressant-like effect. Also, a reduction in frequency and duration of open arms exploration was observed in the elevated plus-maze (EPM) test in stressed mice, and administration of MH (5, 10, 20 mg/kg, IP) reversed these effects. An increase in blood levels of glucose, triglycerides, total cholesterol, and brain malondialdehyde and nitrite levels was observed in the stressed groups, which was reversed by MH. Furthermore, MH reversed the stress-induced reduction in HDL cholesterol and glutathione (GSH) levels and attenuated stress-induced alterations in the prefrontal cortex and hippocampus. Conclusion: Our findings suggest that MH attenuated chronic restraint stress-behavioral and biochemical perturbations, probably due to its capability to decrease oxidative stress and brain neuronal damage