Maternal Protein Restriction Reduces Angiotensin II AT₁ and AT₂ Receptor Expression in the Fetal Rat Kidney

Maternal dietary protein restriction during pregnancy results in an increase in offspring blood pressure in the rat. The kidneys of the low protein (LP) rat have fewer nephrons, increased hemodynamic sensitivity to angiotensin II and lower glomerular filtration rate, suggesting altered activity of the renin-angiotensin system. Angiotensin II plays a role in nephrogenesis through the AT(1) and AT(2) receptor subtypes. The aim of this study was to determine expression levels of both subtypes during nephrogenesis. Pregnant Wistar rats were fed either a control 18% protein diet or a low 9% protein (LP) diet. A 35% reduction in nephron number (p < 0.05) associated with a 50% reduction in total glomerular volume (p < 0.001) was seen in LP rats. Renal AT(1) (p < 0.0001) and AT(2) (p < 0.0001) receptor protein expression were significantly lower in LP rats from E18 to day 10. AT(1) expression in LP rat kidneys tended to increase over time while AT(2) expression declined until day 10, when it began to increase again. Angiotensin II-regulated cell proliferation may be perturbed in the LP rat kidney during nephrogenesis which could contribute to the reduction in nephron number and the elevation in blood pressure observed in this model of programmed hypertension.