Crocin exhibits an antihypertensive effect in a rat model of gestational hypertension and activates the Nrf-2/HO-1 signaling pathway

Gestational hypertension is a leading cause of both prenatal and maternal mortality and morbidity; however, there have been rather limited advances in the management of gestational hypertension in recent years. There has been evidence supporting the antihypertensive properties of crocin, but the specific mechanism is still unclear. N-Nitro-L-arginine methyl ester (L-NAME) was employed to establish a rat model with a preeclampsia-like phenotype, particularly gestational hypertension. Enzyme-linked immunosorbent assays were conducted to determine the levels of placental growth factor (PlGF) and soluble fms-like tyrosine kinase (sFlt-1); the levels of the circulating cytokines interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α; and oxidative stress factors. Quantitative RT-PCR assays were performed to assess the transcript levels of various cytokines in the placenta, and western blot assays were carried out to evaluate the protein levels of heme oxygenase-1 (HO-1) and nuclear factor-erythroid 2-like 2 (Nrf-2). Treatment with crocin reduced the blood pressure of rats with gestational hypertension, which was accompanied by suppressed circulating levels of PlGF and sFlt-1. Crocin further alleviated the inflammatory signals and oxidative stress in the serum, as well as in placental tissues, in rats with L-NAME-induced hypertension. Crocin treatment also improved pregnancy outcomes in terms of fetal survival, fetal weight, and the fetal/placental weight ratio. Finally, in hypertension elicited by L-NAME, crocin stimulated the placental Nrf-2/HO-1 pathway. Crocin alleviated inflammatory and oxidative stress in placental tissues, thereby protecting against gestational hypertension, one of the major phenotypes of preeclampsia, and activated the Nrf-2/HO-1 pathway.