Abnormal development of cerebral arteries and veins in offspring of experimentally preeclamptic rats: Potential role in perinatal stroke

Abstract

Preeclampsia, a hypertensive disorder of pregnancy, complicates up to 10 % of all pregnancies and increases the risk for perinatal stroke in offspring. The mechanism of this increase is unknown, but may involve vascular dysfunction. The goal of this study was to evaluate the effect of experimental preeclampsia (ePE) on cerebrovascular function in offspring to eludciate a possible mechanism for this association. Dams were fed a high cholesterol diet beginning on day 7 of gestation to induce experimental preeclampsia. Middle cerebral arteries (MCA) and the Vein of Galen (VoG) were isolated from pups from ePE dams and compared to pups from normal pregnant (NP) dams at postnatal days 16, 23, and 30 and studied pressurized in an arteriograph chamber. Markers of inflammation and oxidative stress were measured in serum. Our results suggest altered structure and function in both MCA and VoG of ePE pups. We also found evidence of systemic inflammation and oxidative stress in ePE pups. These findings provide a potential link between preeclampsia and the occurrence or severity of perinatal stroke.

Keywords: Cerebral vasculature; Middle cerebral artery; Offspring; Preeclampsia; Vein of galen.

Figure 1.. Weight and crown-rump length in NP vs. ePE rat pups.

Body weights were lower at p30 in ePE pups, and crown-rump lengths were less in ePE pups at p23 and p30, suggesting growth restriction in pups from ePE dams. Number of pups (n) embedded in bars; *p < 0.05 NP vs. ePE.

Figure 2.. Passive inner diameters of MCAs at 5 mmHg in NP vs. ePE pups and stress-strain curves for MCAs at p16, p23, and p30.

MCAs in NP pups showed enlargement with age that did not occur in ePE pups. MCAs in NP pups were larger at p30 but did not achieve significance. *p<0.05 NP vs. ePE.

Figure 3.. Myogenic tone and lumen diameter for NP vs. ePE pups at p16, p23, and p30.

Figures 3a, c, e show myogenic tone in MCA over a range of intravascular pressures for NP vs. ePE pups at p16, p23, and p30. MCA lumen diameter at each pressure (within groups) was also compared to lumen diameter at 25 mmHg (Figures 3b, d, f). In both NP and ePE pups at all 3 time points, lumen diameter was significantly higher than lumen diameter at 25 mmHg at pressures above 100–125mmHg. *P<0.05 NP vs. ePE; ^#P<0.05 NP p16 vs. p30, ^‡P<0.05 p16 vs p23 and p23 vs. p30; ^†P<0.05 vs. diameter at 25mmHg within groups.

Figure 4:. Percent reactivity of VoG to sodium nitroprusside (SNP) in NP and ePE pups at p16, p23, and p30.

Graphs showing reactivity to increasing concentration of SNP over age in NP and ePE pups. Maturation had no significant effect on reactivity in VoG.

Figure 5:. Percent constriction to L-NAME in VoG at p16, p23 and p30.

Graphs showing constriction to a single concentration (10⁻³ M) of the NOS inhibitor L-NAME at different ages. Veins from all groups at all ages constricted only ~5–10% to L-NAME. At p30, VoG from NP pups had a significantly lesser constriction to L-NAME compared to ePE. There was no effect of maturation on NP pups, but ePE pups showed significantly more constriction to L-NAME when p16 was compared to both p23 and p30. *P<0.05 ePE vs. NP, ^†P<0.05 ePE p16 vs. ePE p23; ^††P<0.01 ePE p16 vs. ePE p30.

Figure 6.. Percent change in VoG lumen diameter to U46619 at p16, p23, and p30.

All veins at all ages constricted to U46619. At p23 and p30, VoG constricted significantly more at higher doses of U46619, compared to ePE. At the highest dose of U46619 (1 μM) maturation did not affect constriction to U46619. However, in ePE pups, 1 μM U46619 caused significantly more constriction over maturation (p16 vs. p23 and p16 vs. p30). *P<0.05 for NP vs. ePE, ^††P<0.01 p16 vs. p23 and p16 vs. p30.

Figure 7.. Markers of systemic inflammation and oxidative stress in pups from ePE dams.

Examination of serum from rat pups at p23 and p30 revealed elevation of proinflammatory cytokines (TNF-α) proteins associated with systemic inflammation (TREM-1, TIMP-1; Notch-1; TIM-1), and oxidative stress (8-isoprostane). * p<0.05; ** p<0.01

Figure 8.. Dysregulation of systemic anti-inflammatory cytokine (IL-10) and anti-inflammatory cytokine-like protein (Galectin-1).

Both proteins are elevated at p23 in ePE pups, which may reflect an anti-inflammatory response to systemic inflammatory caused by ePE in dams. This response appears to disappear by p30, which may confer a loss of anti-inflammatory effect by this time point. IL-10 concentration at p23 in ePE pups approached, but did not reach, statistical significance (P=0.05). * p<0.05; ** p<0.01

Figure 9.. Systemic chemokines in serum of pups from ePE pups at p23 and p30.

Proteins involved in monocyte attraction/vascular inflammation (MCP-1); leukocyte migration at vascular endothelium (L-selectin); and transmigration of leukocytes into vessel walls/vascular inflammation (JAM-A). * p<0.05; ** p<0.01