The effects of baicalin on the TLR2/4 signaling pathway in the peripheral blood mononuclear cells of a lipopolysaccharide-induced rat fever model

Baicalin, which is a flavonoid compound isolated from Scutellariae radix, has significant antipyretic effects. The aim of the present study was to evaluate the effects of baicalin on the Toll-like receptor 2/4 (TLR2/4) signaling pathway in the peripheral blood mononuclear cells (PBMCs) of a rat fever model induced by lipopolysaccharide (LPS). Sprague-Dawley rats were injected intraperitoneally with 100 μg/kg LPS with or without a 160 mg/kg baicalin treatment to induce fever. The results showed that baicalin significantly reduced the body temperatures of the fever-induced rats, inhibited the LPS-modulated upregulation of TLR4 mRNA and protein expression and TNF-α and IL-1β mRNA expression in the rat PBMCs and downregulated nuclear factor-κB activation with simultaneous decreases in TNF-α and IL-1β protein expression. The LPS and baicalin had no significant effect on TLR2 mRNA or protein expression in the PBMCs. These data suggest that baicalin can inhibit the TLR4 signaling pathway in the PBMCs of our animal model. Our findings may provide new mechanistic insights into the antipyretic effects of baicalin.