The effects of frankincense extract on depression and anxiety-like behaviors induced by lipopolysaccharide in rats

Abstract The neuroimmune system has been suggested to play a role in the ethiology of depression and anxiety. Frankincense extract is an herb that has been considered to be an anti-inflammatory agent potentially useful in the treatment of specific neuroimmune system disorders. The present study examined the effects of frankincense ethyl acetate extract on lipopolysaccharide (LPS) - induced depression and anxiety-like behavior in rats. Fifty male Wistar rats received vehicle, 1 mg/kg LPS or 50, 100 or 200 mg/ kg of extract with LPS for 6 days. Forced swim test (FST), elevated plus-maze (EPM) and open field (OF) tests were done in order to assess depression and anxiety-like behaviors. Serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF- α) levels were evaluated to measure the anti-inflammatory properties of the extract. LPS resulted in depression and anxiety-like behaviors (increased immobility in the FST, decreased time in the central area in the OF, and reduced time in the open arms in the EPM, as well as increased markers of inflammation (IL-6 and TNF-α). Behaviors consistent with anxiety and depression, as well as increased markers of inflammation were reduced by frankincense extract treatment, especially at the highest, 200 mg/kg dose. We conclude that the ethyl acetate extract of frankincense extract can mitigate the LPS-induced depression and anxiety-like behaviors in behavioral testing through reduction of inflammatory cytokines.