Forsythin inhibits 8-hydroxybutyrate-induced oxidative stress in bovine macrophages by regulating p38/ERK, PI3K/Akt, and Nrf2/HO-1 signaling pathways

Ketosis is a metabolic disease of dairy cows in the perinatal period, 8-hydroxybutyrate (8-HB) is the main component of ketosis. High levels of 8-HB can trigger oxidative stress and inflammatory response in dairy cows, leading to decreased milk yield and multiple postpartum diseases. Forsythin (FOR), the major constituent of the herbal medicine Forsythia, has anti-inflammatory, anti-oxidant, and antiviral effects. FOR was demonstrated to have an antioxidant effect on PC12 cells. However, the effects of FOR on 8-HB-stimulated bovine macrophages (BMs) has not been reported. Thus, the aim of the present study was to investigate the effects of FOR on 8-HB-stimulated BMs. Firstly, the CCK8 test confirmed that FOR (50, 100, 200 mu g/mL) has no effect on BMs activity, and we selected these concentrations for subsequent experiments. Secondly, through detecting the oxidation indexes ROS, MDA and antioxidant indexes CAT and SOD, we confirmed the antioxidant effect of FOR on BMs. Next, qRT-PCR confirmed that FOR dramatically reduced the mRNA levels of IL-18 and IL-6. Furthermore, the western blotting confirmed that FOR observably down-regulated 8-HB-stimulated phosphorylation of p38, ERK and Akt and up-regulated expression of Nrf2, and HO-1. Above results suggested that FOR plays antioxidant effects on 8-HB-induced BMs through p38, ERK and PI3K/Akt, Nrf2 and HO-1 signaling pathways. Therefore, we speculated that FOR may be a potential medicine to alleviate 8-HB-induced inflammatory response and provide a preliminary reference for the research and development of FOR.