Foeniculum vulgare Mill. inhibits lipopolysaccharide-induced microglia activation and ameliorates neuroinflammation-mediated behavioral deficits in mice

Abstract

Objective: To investigate the effect of Foeniculum vulgare extract against lipopolysaccharide (LPS)-induced microglial activation in vitro as well as cognitive behavioral deficits in mice. Methods: LPS-activated BV-2 cell viability was measured using MTT assay and reactive oxygen species (ROS) was studied using DCF-DA assay. The antioxidative enzymes and pro-inflammatory mediators were analyzed using respective ELISA kits and Western blotting. For in vivo testing, LPS (1 mg/kg, i.p.) was given daily for five days in male Swiss albino mice to produce chronic neuroinflammation. Cognitive and behavioral tests were performed using open-field, passive avoidance, and rotarod experiments in LPS-induced mice. Results: Foeniculum vulgare extract (25, 50 and 100 μg/mL) significantly attenuated the LPS-activated increase in nitric oxide (NO), ROS, cyclooxygenase-2, inducible NO synthase, IL-6, and TNF-alpha (P < 0.05). Moreover, LPS-induced oxidative stress and reduced antioxidative enzyme levels were significantly improved by Foeniculum vulgare extract (P < 0.05). The extract also regulated the NF-κB/MAPK signaling in BV-2 cells. In an in vivo study, Foeniculum vulgare extract (50, 100, and 200 mg/kg) markedly mitigated the LPS-induced cognitive and locomotor impairments in mice. The fingerprinting analysis showed distinctive peaks with rutin, kaempferol-3-O-glucoside, and anethole as identifiable compounds. Conclusions: Foeniculum vulgare extract can ameliorate LPS-stimulated neuroinflammatory responses in BV-2 microglial cells and improve cognitive and locomotor performance in LPS-administered mice.

Keywords

• foeniculum vulgare; microglia; lipopolysaccharide; antioxidant; neuroinflammation; mapk signaling; cognition