Abstract

Several factors are associated with bronchopulmonary dysplasia. Among them, hyperoxia and lung immaturity are considered to be fundamental; however, the effect of malnutrition is unknown. Our objective was to evaluate the effects of 7 days of postnatal malnutrition and hyperoxia on lung weight, volume, water content, and pulmonary morphometry of premature rabbits. After c-section, 28-day-old New Zealand white rabbits were randomized into four groups: control diet and room air (CA, N = 17), control diet and > or = 95% O2 (CH, N = 17), malnutrition and room air (MA, N = 18), and malnutrition and > or = 95% O2 (MH, N = 18). Malnutrition was defined as a 30% reduction of all the nutrients provided in the control diet. Treatments were maintained for 7 days, after which histological and morphometric analyses were conducted. Lung slices were stained with hematoxylin-eosin, modified orcein-resorcin or picrosirius. The results of morphometric analysis indicated that postnatal malnutrition decreased lung weight (CA: 0.83 +/- 0.19; CH: 0.96 +/- 0.28; MA: 0.65 +/- 0.17; MH: 0.79 +/- 0.22 g) and water content, as well as the number of alveoli (CA: 12.43 +/- 3.07; CH: 8.85 +/- 1.46; MA: 7.33 +/- 0.88; MH: 6.36 +/- 1.53 x 10-3/mm) and elastic and collagen fibers. Hyperoxia reduced the number of alveoli and increased septal thickening and the mean linear intercept. The reduction of alveolar number, collagen and elastic fibers was intensified when malnutrition and hyperoxia were associated. These data suggest that dietary restriction enhances the magnitude of hyperoxia-induced alveolar growth arrest and lung parenchymal remodeling. It is interesting to consider the important influence of postnatal nutrition upon lung development and bronchopulmonary dysplasia.

Highlights

  • Bronchopulmonary dysplasia involves histopathological pulmonary changes resulting from an inflammatory process induced by hyperoxia [1,2], infection [3], and mechanical ventilation [4], conditions associated with the peculiarities of the developing immature lung

  • Pulmonary effects Malnutrition induced lower of lung weight, lung weight corrected for birth weight, specific lung volume and water content (P < 0.05) in premature rabbits

  • The present study showed that malnutrition reduced lung weight, lung weight/birth weight ratio, specific lung volume and water content, as well as the number of alveoli and elastic fibers and collagen deposition

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Summary

Introduction

Several experimental studies have described the acute lung injury caused by hyperoxia in adult animals [5,6] as well as in premature animals [7,8,9,10,11,12,13,14] during the period in which the lung is still in the process of alveolarization. This injury is characterized by arrested alveolar and pulmonary microvascular development [5,6,15,16]. Other investigators did not observe any influence of malnutrition on the pulmo-

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