Anti-inflammatory and analgesic effect of Forsythiaside B on complete Freund's adjuvant-induced inflammatory pain in mice

Chronic pain is frequently reported in clinical practice. Therefore, it is important to identify effective therapy to relieve pain. In this work, we selected Forsythoside B (FB), a phenylethanoid glycoside isolated from Forsythia suspensa (Thunb.) Vahl, to evaluate its effect in modulating inflammatory pain induced by complete Freund's adjuvant (CFA) and the involved mechanisms. We discovered that FB could attenuate inflammatory pain triggered by CFA injection and exert anti-anxiety effects. In detail, proinflammatory cytokines, consisting of IL-6 and TNF-α, were decreased after FB administration in the CFA-injected mice. Furthermore, the FB application ameliorated the activation of ionized calcium-binding adaptor molecule 1 (Iba-1) and glial fibrillary acidic protein (GFAP), the microglia and astrocytes markers respectively. Therefore, our findings indicate that FB could be a promising treatment for chronic inflammatory pain. •Forsythiaside B ameliorates complete Freund's adjuvant (CFA) induced thermal hypersensitivity and mechanical allodynia.•Forsythiaside B exerts anxiolytic effects in CFA-injected mice.•Forsythiaside B decreases CFA-induced proinflammatory cytokines level in the spinal cord.•Forsythiaside B attenuates CFA-triggered microglia and astrocyte activation in the spinal cord.