Protein Deficiency and the Growing Rat Lung. I. Nutritional Findings and Related Lung Volumes

Abstract

We investigated the consequences of early malnutrition on milk production by dams and on body weight and structural lung growth of young rats using two models of protein restriction. Dams of the early restriction group were fed an 8% casein diet starting at parturition. Those of the delayed restriction group received a 12% casein diet from lactation d 8-14 and thereafter the 8% diet. After weaning, early restriction and delayed restriction group rats were maintained on low protein until d 49, then refed the control diet (18% casein) up to d 126. Milk was analyzed on d 12. Animals were killed at d 21, 49, and 126 for lung fixation in situ. In this report, we show that protein restriction lowered milk yield to 38% of normal. Milk lipid per gram of dry weight tended to be increased, whereas lactose and protein were significantly decreased. Pups from protein-restricted dams grew less and had lower lung volumes, effects being more serious at d 49. However, specific lung volumes (in milliliters per 100 g body weight) were constantly increased. This means that lung was either less affected than body mass or overdistended due to less connective tissue. After refeeding, both groups showed a remarkable catch-up in growth with restoration of the normal allometric relationship between lung volume and body weight. Thus, even after an early onset of protein restriction to total body, the lung is still capable to substantially recover from growth retardation. (Pediatr Res 37: 783-788, 1995) Abbreviations ER, early restriction in protein DR, delayed restriction in protein From experimental studies in animals, it is well documented that food deficiencies result in growth retardation along with functional alterations of the lung. Two recent publications have substantially reviewed the literature on the topic (1, 2). The majority of studies have concerned the rat because in this species the different processes of growth and development of the lung are well characterized (3-6). In this respect, critical transformations of the lung parenchyma in the postnatal period corresponding to the developmental steps of alveolization and microvascular maturation occur before the age of 3 wk. In normal conditions, the volume of the lung is largely determined by the dimension of the thoracic cage, which in turn depends allometrically on the body mass of the rat (7). Similarly, the quantitative parameters of the various components of the parenchyma are known to be related to lung volume (4). All of these lung parameters also vary with both the metabolic needs and the 0, demands of the organism (8) and the 0, in the ambient air (9).The effects on the rat lung of malnutrition beginning during the neonatal period (i.e. the period of suckling) are not well

Effect of postnatal malnutrition on hyperoxia-induced newborn lung development

“…Although some studies using models of malnutrition found that this treatment induced higher specific lung volumes, other studies obtained contradictory results (14,15). The studies that detected higher specific lung volumes also found greater alveolar size, while a subset also observed emphysematous segments (36). These inconsistent results might reflect differences in the degree of malnutrition or the type of nutrients restricted, as well as the time of onset of treatment.…”

“…The other models use a reduction of several degrees of nutrients administered to animals. As the pups of the present study were unable to suck, a 30% reduction of the nutrients of the control diet was chosen, as also done in other studies (19,20,35,36). This diet is similar to that used in other premature rabbit models (8,13).…”

Effects of nutrition, growth hormone disturbances, training, altitude and sleep on lung volumes

“…The structure of the lung parenchyma of rats restricted in protein during early and late postnatal periods has been studied after refeeding for 11 weeks. All parenchymal subcomponents grew consistently with normal volume and surface densities [6,7] as compared to controls, indicating that recovery occurs after refeeding.…”

Bronchopulmonary dysplasia prediction model for 7-day-old infants

“…Da mesma forma, nossos RN com PCA na pri- [24][25][26] . Além disso, apesar de apenas 11% do total dos pacientes terem recebido terapia com diuré- Modelo preditivo para displasia broncopulmonar -Bhering CA et al…”