36 Effects of Intrauterine Growth Restriction (Iugr) and Postnatal Catch-Up Growth on Arterial Blood Pressure (Bp), Glucose Tolerance (Gt) and Renal Function in Adult Rats

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Background: Epidemiological and experimental studies have demonstrated a relationship between low birth weight and increased risk of hypertension and metabolic diseases in adulthood. Rapid postnatal catch-up growth, favoured by high caloric and proteins intakes, may constitute an additional risk factor.Aim: to investigate the effects of early postnatal overfeeding (OF) after IUGR on arterial systolic blood pressure (SBP), GT, and renal function in adult rats. Methods: 4 groups of animals were investigated from birth to 16 weeks: group I, controls: offspring of dams fed normal diet (NP, casein 22 %); group II: offspring of dams fed isocaloric low-protein diet (LP, casein 9 %); group III, same conditions as group I, postnatal OF; group IV: same conditions as group II, postnatal OF. OF was obtained by reduction of litter size down to 3 pups from day 3. SBP was measured at 4 and 8 weeks, and glomerular number was determined in newborn pups. Renal function (creatinine clearance (CrCl), fractional excretion of sodium (FeNa), proteinuria (PROT)) and glycaemia were assessed at 16 weeks of age. Data were analyzed by Kruskall-Wallis and Mann-Withney tests.Results: (mean +/− SEM). Offspring of dams fed LP diet had a 20 % birth weight reduction (p <0.001). Group III pups had the higher growth rate during suckling period (p <0.05). Although smaller at birth, group IV rats caught up the weight of control offspring within the first postnatal month. Catch-up growth was associated with an elevated SBP at 4 weeks of age (110 +/−3; 117 +/− 2; 116 +/− 3; 127 +/− 2 mmHg in groups I, II, II, IV respectively; p <0.05). During adulthood, SBP was significantly elevated in groups II, III, IV in comparison with group I (144 +/− 3; 146 +/−1.6; 144,5 +/− 3; 130 +/− 3 mmHg, respectively; p <0.05). Despite a 38 % reduction of glomerular number in pups exposed in utero to LP diet (p <0.05), CrCl and FeNa were not different between the groups. However, PROT was higher in rats that were exposed both to in utero LP diet and OF (10.9 +/− 1.4; 13.7 +/− 2; 19.2 +/− 5; 30.2 +/− 7 mg /Kg/day in groups I, II, III, IV respectively; p <0.05). Group III rats had a higher glycaemia in comparison with groups I and II rats (1.43; 1.74; 2.09; 1.84 g/l in groups I, II, III, IV respectively).Conclusion: Early catch-up growth in IUGR rats enhances alteration of SBP, glucose tolerance and renal function in adulthood. Single nephron hyperfiltration rate may occur in such condition, and may cause BP, and renal function alterations.