Perinatal iron deficiency and a high salt diet cause long-term kidney mitochondrial dysfunction and oxidative stress.

Abstract

Perinatal iron deficiency (ID) alters developmental trajectories of offspring, predisposing them to cardiovascular dysfunction in later life. The mechanisms underlying this long-term programming of renal function have not been defined. We hypothesized perinatal ID causes hypertension and alters kidney metabolic function and morphology in a sex-dependent manner in adult offspring. Furthermore, we hypothesized these effects are exacerbated by chronic consumption of a high salt diet. Pregnant Sprague Dawley rats were fed either an iron-restricted or replete diet prior to and throughout pregnancy. Adult offspring were fed normal or high salt diets for 6 weeks prior to experimentation at 6 months of age. Blood pressure (BP) was assessed via indwelling catheters in anaesthetized offspring; kidney mitochondrial function was assessed via high-resolution respirometry; reactive oxygen species and nitric oxide were quantified via fluorescence microscopy. Adult males, but not females, exhibited increased systolic BP due to ID (P = 0.01) and high salt intake (P = 0.02). In males, but not in females, medullary mitochondrial content was increased by high salt (P = 0.003), while succinate-dependent respiration was reduced by ID (P < 0.05). The combination of perinatal ID and high salt reduced complex IV activity in the cortex of males (P = 0.01). Perinatal ID increased cytosolic superoxide generation (P < 0.001) concomitant with reduced nitric oxide bioavailability (P < 0.001) in male offspring, while high salt increased mitochondrial superoxide in the medulla (P = 0.04) and cytosolic superoxide within the cortex (P = 0.01). Male offspring exhibited glomerular basement membrane thickening (P < 0.05), increased collagen deposition (P < 0.05), and glomerular hypertrophy (interaction, P = 0.02) due to both perinatal ID and high salt. Female offspring exhibited no alterations in mitochondrial function or morphology due to either high salt or ID. Perinatal ID causes long-term sex-dependent alterations in renal metabolic function and morphology, potentially contributing to hypertension and increased cardiovascular disease risk.