To investigate the effect of matrine on endothelial injury and the Janus-activated kinase 2 / signal transducer and activator of transcription 3 / suppressor of cytokine signaling-1 ( JAK2 / STAT3 / SOSC1) signaling pathway in rats with pregnancy-induced hypertension (PIH). Methods Sixty pregnant rats were randomly separated into normal control group, model control group, low dose matrine group, high dose matrine group and magnesium sulfate group, with 12 rats in each group. Pregnant rats in each group except the normal control group were intragastrically administered 50 mg / kg nitroso-L-arginine methyl ester on day 12 of pregnancy to establish a PIH rat model. On day 16 of pregnancy, low and high dose matrine groups were administered intragastrically with 50 and 100 mg / kg matrine, respectively, the magnesium sulfate group was administered intragastrically with 100 mg / kg magnesium sulfate, and normal and model control groups were administered intragastrically with an equal volume of saline. A rat non-invasive sphygmomanometer and Coomassie blue staining were used to assess tail artery blood pressure and the 24 h urine protein content of pregnant rats in each group on day 16 (before administration), day 17 and day 21 of pregnancy. Enzyme-linked immunoassays were used to determine the levels of superoxide dismutase ( SOD), malondialdehyde ( MDA), tumor necrosis factor-α ( TNF-α), interleukin (IL)-6, IL-10, endothelin (ET), thromboxane B2 ( TXB2), nitric oxide (NO), and 6-keto-prostaglandin F1α ( 6-keto-PGF1α). Western blot was used to measure JAK2, p-JAK2, STAT3, p-STAT3 and SOSC1 protein expression in rat placental tissue. Results On the days 17 and 21 of pregnancy, blood pressure and the 24 h urine protein content of pregnant rats in the model control group were significantly higher than those in the normal control group (P< 0. 05), and blood pressure and the 24 h urine protein content of pregnant rats in low and high dose matrine groups were significantly lower than those in the model control group (P<0. 05). Compared with the normal control group, serum levels of SOD, IL-10, NO and 6-keto-PGF1α in the model control group were lower, and MDA, TNF-α, IL-6, ET and TXB2 levels and p-JAK2 / JAK2, p-STAT3 / STAT3 and SOSC1 protein expression in placental tissue were higher ( P< 0. 05). Compared with the model control group, SOD, IL-10, NO and 6-keto-PGF1α in low and high dose matrine groups were increased sequentially, and MDA, TNF-α, IL-6, ET and TXB2 levels and p-JAK2 / JAK2, p-STAT3 / STAT3, and SOSC1 protein expression in placental tissue were decreased sequentially (P<0. 05). Compared with the magnesium sulfate group, the above indicators in the high dose matrine group showed no significant changes ( P > 0. 05 ). ConclusionsMatrine decreases blood pressure, urinary protein content, inflammatory responses, and oxidative stress, inhibits JAK2 and STAT3 phosphorylation and SOSC1 protein expression, and then alleviates endothelial injury in PIH rats