H2S donor GYY4137 mitigates sFlt-1-induced hypertension and vascular dysfunction in pregnant rats†

Abstract

Gestational hypertension, often associated with elevated soluble Fms-related receptor tyrosine kinase 1 (sFlt-1), poses significant risks to both maternal and fetal health. Hydrogen sulfide (H2S), a gasotransmitter, has demonstrated blood pressure-lowering effects in hypertensive animals and humans. However, its role in pregnancy-induced hypertension remains unclear. This study investigated the impact of GYY4137, a slow-release H2S donor, on sFlt-1-induced hypertension in pregnant rats . Pregnant rats were administered sFlt-1 (6 μg/kg/day, intravenously) or vehicle from gestation day (GD) 12-20. A subset of these groups received GYY4137 ( 50 mg/kg/day, intraperitoneal) from GD 16-20. Serum H2S levels, mean arterial blood pressure, uterine artery blood flow, and vascular reactivity were assessed. Elevated sFlt-1 reduced both maternal weight gain and serum H2S levels. GYY4137 treatment restored both weight gain and H2S levels in sFlt-1 dams. sFlt-1 increased mean arterial pressure and decreased uterine artery blood flow in pregnant rats. However, treatment with GYY4137 normalized blood pressure and restored uterine blood flow in sFlt-1 dams. sFlt-1 dams exhibited heightened vasoconstriction to phenylephrine and GYY4137 significantly mitigated the exaggerated vascular contraction. Notably, sFlt-1 impaired endothelium-dependent relaxation, while GYY4137 attenuated this impairment by upregulating eNOS protein levels and enhancing vasorelaxation in uterine arteries. GYY4137 mitigated sFlt-1-induced fetal growth restriction. In conclusion, sFlt-1 mediated hypertension is associated with decreased H2S levels. Replenishing H2S with the donor GYY4137 mitigates hypertension and improves vascular function and fetal growth outcomes. This suggests modulation of H2S could offer a novel therapeutic strategy for managing gestational hypertension and adverse fetal effects.

Keywords: GYY4137; endothelium; hydrogen sulfide; hypertension; pregnancy; sFlt-1; uterine artery.

Graphical Abstract

Figure 1

Maternal weight gain and serum H₂S levels. Pregnant rats were exposed to intravenous sFlt-1 (6 μg/kg/day) or vehicle from gestational day (GD) 12 to 20. Both sFlt-1 and control groups received H₂S donor GYY (50 mg/kg, i.p.) from GD 16 to 20. (A) Maternal weight change on GD 20 relative to GD 12 is shown as a percentage. (B) Serum H₂S levels were determined as described in the methods section. Data are means ± SEM of 6 rats per group. Bars with asterisk (*) denote significant differences (P ≤ 0.05).

Figure 2

Maternal blood pressure response to H₂S donor GYY. Pregnant rats received sFlt-1 (6 μg/kg/day, i.v.) or vehicle from gestational day (GD) 12–20. GYY (50 mg/kg, i.p.) was administered to both sFlt-1 and control groups from GD 16 to 20. On GD 20, mean arterial blood pressure was noninvasively assessed using the CODA system. Data are means ± SEM of 6 rats per group. ^*Denote significant differences (P ≤ 0.05) relative to other groups.

Figure 3

Uterine artery hemodynamics after H₂S donor GYY treatment. Uterine artery (A) blood flow, (B) resistance index, and (C) pulsatility index were assessed using a 30-MHz transducer and Vevo 2100 micro-ultrasound on gestational day 19 in control and sFlt-1 dams with or without GYY. Data are means ± SEM of 6 rats per group. Bars with asterisk (*) denote significant differences (P ≤ 0.05).

Figure 4

Uterine artery contractility following H₂S donor GYY treatment. Uterine artery rings were obtained from pregnant rats on gestational day 20 after exposure to control or sFlt-1, with or without GYY treatment. Vascular contractile responses to cumulative phenylephrine (PE) additions were assessed in endothelium-removed rings and shown as (A) percentage of maximal contraction and (B) percentage of contraction elicited by 80 mM potassium chloride (KCl). (C) Contractile responses to 80 mM KCl. Data are means ± SEM of 6 rats per group. ^*P ≤ 0.05 compared to all other groups.

Figure 5

Uterine artery relaxation after H₂S donor GYY treatment. Uterine artery rings were obtained from pregnant rats on gestational day 20 after exposure to control or sFlt-1, with or without GYY treatment. Rings were pre-contracted with submaximal phenylephrine and then the relaxation responses to cumulative doses of (A) acetylcholine (ACh) in endothelium-intact rings and (B) sodium nitroprusside (SNP) in endothelium-removed rings were assessed. Data are means ± SEM of 6 rats per group. ^*P ≤ 0.05 compared to other groups.

Figure 6

Uterine artery endothelial nitric oxide synthase (eNOS) protein expression after H₂S donor GYY treatment. Uterine artery samples from pregnant rats on gestational day 20 after exposure to control or sFlt-1, with or without GYY treatment, were subjected to Western blotting for eNOS expression. The top panel shows representative blots for eNOS and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), while the bottom panel presents normalized densitometry data. Data are means ± SEM of 6 rats per group. Bars with asterisk (*) denote significant differences (P ≤ 0.05).

Figure 7

Litter size, fetal, and placental weights after H₂S donor GYY treatment. Pregnant rats were exposed to control or sFlt-1, with or without GYY treatment. Litter size, fetal and placental weights were recorded on gestational day 20. (A) Litter size (B) male fetal weights (C) female fetal weights (D) male placental weights, and (E) female placental weights were calculated as the mean data per dam/litter. Data are means ± SEM of 6 rats per group. Bars with asterisk (*) denote significant differences (P ≤ 0.05).