Respostas pulmonares à restrição nutricional e à hiperoxia em coelhos prematuros

Abstract

Objectives: To analyze the effects of nutritional restriction and hyperoxia on lung weight and pulmonary morphometry in premature rabbits during the first 11 days of life.Methods: New Zealand White rabbits were delivered by C-section at 28 days gestational age and randomized into four groups: control diet and room air, control diet and hyperoxia (> 95% O 2 ), nutritional restriction and room air and nutritional restriction and hyperoxia (> 95% O 2 ). Nutritional restriction was achieved by reducing all nutrients by 30% in comparison with the control diet. Lung tissue slides were stained with hematoxylin-eosin, modified resorcin-orcein and picrosirius, before morphometric analysis was performed.Results: From the fourth day onwards, less weight was gained by the nutritional restriction and hyperoxia group (p < 0.001) and from the sixth day on, by the nutritional restriction and room air group (p < 0.001), in comparison with their respective control groups. Nutritional restriction decreased alveoli number (p < 0.001) and collagen deposition (p < 0.001). Hyperoxia was responsible for reductions in number of alveoli (p < 0.001) and collagen deposition (p < 0.001), in addition to higher mean linear intercept values (p < 0.05) and thickening of alveolar septa (p < 0.001). When nutritional restriction was associated with hyperoxia, the reductions in number of alveoli (p < 0.001) and of collagen deposition (p < 0.001) intensified.Conclusions: Nutritional restriction intensified the changes of pulmonary architecture findings caused by hyperoxia, in particular through alterations to alveolarization and collagen deposition.J Pediatr (Rio J). 2006;82(3):179-85: Nutritional restriction, hyperoxia, lung development, premature rabbits.