Abstract: Objective To investigate the effect of kaempferol (Kpf) on inflammatory responsein rats with gestational diabetes mellitus (GDM) by regulation of the interleukin-6 (IL-6) / signaltransducer and activator of transcription 3 (STAT3) signaling pathway. Methods A rat model ofGDM was constructed by the combination of high fat and high sugar diets and intraperitoneal injection of streptozotocin ( STZ). GDM rats were then randomly divided into 5 groups: Model group, Kpf low-, medium-, and high-dose groups, and activator group ( IL-6 / STAT3 pathway activator rIL-6), with 12 rats in each group, another 12 rats without any special treatment as the control. Intraperitoneal injection of the corresponding drug was performed once a day until the 19th day of pregnancy. Roche blood glucose meter was applied to measure fasting blood glucose ( FBG) in rats. The pregnancy outcomes of rats in each group were analyzed. ELISA method was applied to determine the levels of fasting insulin (FINS) in rat serum and interleukin-6, interleukin-1β (IL-6, IL-1β), and tumor necrosis factor-α ( TNF-α) in placental tissues. Hematoxylin-eosin ( HE) staining was applied to observe pathological damage in rat placental tissues. TUNEL staining was applied to detect apoptosis in placental tissues. The expression levels of IL-6 / STAT3 pathway proteinsin placental tissues were detected by Western blotting. Results The values of FBG, FINS, HOMA-IR, fetal mouse weight, the levels of IL-6, IL-1β, TNF-α, the apoptosis rate of placental tissue cells, the expression levels of IL-6, p-STAT3 / STAT3 proteins in the Model group were increased when compared with those in the control group, while the live birth rate and the number ofoffspring were decreased when compared with those in the control group (P < 0. 05). The values ofFBG, FINS, HOMA-IR, fetal mouse mass, the levels of IL-6, IL-1β, TNF-α, the apoptosis rate of placental tissue cells, and the expression levels of IL-6, p-STAT3 / STAT3 proteins in the Kpf low-, medium-, and high-dose groups were decreased when compared with those in the Model group, while the live birth rate and the number of offspring were increased when compared withthose in the Model group (P < 0. 05). The changes of the above indicators in the activator group were reversed when compared to the Kpf high-dose group (P< 0. 05). Conclusion Kpf can alleviate placental inflammation and insulin resistance in GDM rats. Its mechanism may be related to the inhibition of IL-6 / STAT3 signaling pathway.

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