IL18 and infection: When the piglets were injected with baicalin and probenecid, the IL-1β, IL-10, IL-18, TNF-α and IFN-γ mRNA levels decreased compared to those in the infection group (p < 0.01) (Figure 2), which suggested that baicalin and probenecid inhibited cytokine production in piglets infected with G. parasuis.