Does Estrogen Affect the Development of Abnormal Vascular Function in Offspring of Rats Fed a Low-Protein Diet in Pregnancy?

Abstract

It is established that there are gender-related differences in the effects on offspring blood pressure induced by maternal protein restriction in animal studies. Since such effects may depend on estrogen levels, we hypothesized that lower estrogen would induce an earlier onset of hypertension caused by maternal under-nutrition. Wistar rats were fed a diet containing either 18% (C) or 9% (R) casein throughout pregnancy. Half of the offspring in both C and R groups were ovariectomized on day 50 (CX, RX), and the other half underwent a sham operation (CO, RO). On d 175, offspring were killed for small artery reactivity and histologic investigation. Birth weight and later growth were not significantly different between C and R. RX had higher systolic blood pressure than CX on d125, but no difference was seen between RO and CO. On d 175, systolic blood pressure was higher in R than in C, whether or not ovariectomized. Dilator responses to acetylcholine and bradykinin in small mesenteric arteries were significantly attenuated in RX, although responses to SNP and isoprenaline showed no attenuation in R. The ratio of coronary peri-vascular fibrosis to total vascular area was higher in R, and the fibrosis became prominent in ovariectomized rats. These findings suggest that estrogen plays an important role in limiting the elevation of offspring blood pressure induced by maternal under-nutrition, possibly via BK-mediated mechanisms. The processes may underlie gender and life course patterns of hypertension and also the developmental origins of this disease.