Effect of prenatal dexamethasone on rat renal development

BACKGROUND: Prenatal insults can program the developing fetus to develop diseases that manifest in later life. Dexamethasone is often administered to the developing fetus to accelerate pulmonary development. The purpose of the present study was to determine whether prenatal dexamethasone adversely affects renal development and predisposes rats to develop renal disease and hypertension in later life. METHODS: Pregnant rats were given either vehicle or two daily intraperitoneal injections of dexamethasone (0.2 mg/kg body weight) on gestational days: 11 and 12, 13 and 14, 15 and 16, 17 and 18, 19 and 20, or 20 and 21. Tail cuff blood pressure, glomerular number, and inulin clearance were measured in control and prenatal dexamethasone-treated rats when the rats were 60 to 90 days of age. RESULTS: Prenatal dexamethasone did not affect the length of gestation, the number of animals per litter, or the total body weight or kidney weight measured at one day of age. Offspring of rats administered dexamethasone on days 15 and 16 gestation had a 30% reduction in glomerular number compared with control at 60 to 70 days of age (24,236 +/- 441 vs. 30,453 +/- 579, P < 0.01). Rats receiving prenatal dexamethasone on days 17 and 18 had an approximate 20% reduction in glomeruli compared with control (P < 0.01). Offspring of rats receiving dexamethasone on days 15 and 16 gestation had systolic blood pressures at 60 to 90 days of age that were higher than any other group (P < 0.05). The glomerular filtration rate was comparable in all of the groups. CONCLUSIONS: This study shows that two daily doses of prenatal dexamethasone (0.2 mg/kg body weight) in rats do not produce intrauterine growth retardation. Adult offspring of rats that received prenatal dexamethasone during specific times of gestation have a reduced number of nephrons and hypertension.