Glycyrrhizin potentially suppresses the inflammatory response in preeclampsia rat model

The expression of high-mobility group box 1 (HMGB1) in trophoblasts is elevated, which contributes to the development of preeclampsia. Thus, this study aimed to investigate the effect of glycyrrhizin, a natural HMGB1 inhibitor, on the development of preeclampsia.

Preeclampsia was induced in pregnant Lewis rats through oral administration of L-NAME (50 mg/kg/day) on gestational day (GD) 13-19. Glycyrrhizin (10, 30, or 60 mg/kg/day) was given by oral gavage on GD 10-19. Systolic blood pressure (SBP), diastolic blood pressure (DBP), 24-hour proteinuria, live pup birth ratio, pup weight, pup body length, and placental weight were measured. Also, the expression levels of inflammatory factors (TNF-α, iNOS, IL-1, and IL-6), HMGB1, and TLR4 in the placenta or in the serum were analyzed by enzyme-linked immunosorbent assay, RT-PCR, and Western blot analysis.

Glycyrrhizin significantly reduced the SBP, DBP, and 24-hour proteinuria on GD 16 and 20 in a dose-dependent manner and ameliorated the pregnancy outcomes in preeclampsia rats. The elevated inflammatory molecule levels were markedly decreased by glycyrrhizin not only in the serum but also in the placenta. Moreover, the upregulated HMGB1 and TLR4 expression levels were diminished by glycyrrhizin administration.

This study shows that glycyrrhizin could alleviate preeclampsia and the preeclampsia-associated inflammatory reaction, and this effect could be attributed to HMGB1 inhibition.