Mechanisms of Sexual Dimorphism in Perinatal Programming

Oregon Health And Science University, Portland OR

Investigators

Linked publications & trials

Abstract

DESCRIPTION (provided by applicant): Numerous human studies have shown that babies born smaller have an increased adult cardiovascular risk compared to larger babies, indicating that factors in the prenatal environment affecting fetal growth can program the individual for increased cardiovascular risk later in life. One of these factors is maternal protein intake. In rats, maternal protein restriction leads to renal dysfunction and hypertension in the adult offspring. Suppression of the intrarenal rennin/angiotensin system during a critical period in development, and a consequent reduction in nephron endowment, appear to play an important role in this programming. Female offspring are relatively protected from the programming effects of several adverse maternal dietary conditions, including protein restriction. In other animal models, the presence of gonadal hormones during development and/or in adulthood contributes to the sexually dimorphic patterns of hypertension, but the mechanisms by which female gender protects against programming for hypertension by maternal diet are not known. The purpose of this project is to determine the mechanisms responsible for the relative protective effect of female Gender on perinatal programming for hypertension. The overarching hypothesis is that the presence or absence of testosterone during development and/or testosterone or estrogen later in life are responsible for the sexual dimorphism of perinatal programming, and specifically, that these gonadal hormones contribute to programming of offspring hypertension at least in part through permitting suppression of the fetal/newborn intrarenal renin angiotensin system and consequent impairment of renal development, resulting in permanent changes in renal structure and function. In these studies, testosterone and estrogen levels in male and female offspring of normal and protein-restricted mothers will be manipulated during the developmental period and/or in adult life by orchiectomy/ovariectomy and administration of exogenous hormone or by administration of pharmacologic inhibitors. Renal renin-angiotensin system components will be measured in the neonatal period, and arterial pressure, renal function, and glomerular number and volume will be measured in juvenile and adult animals.