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Protein deprivation from the neonatal period impairs lung development in the rat
Insights
Early protein deficiency in neonatal rats impairs lung development, leading to smaller cells and altered mechanics. Malnourished lungs show increased surface forces and rupture resistance, but decreased elastic forces.
Area of Science:
- Pulmonary Medicine
- Developmental Biology
- Nutritional Science
Background:
- Early life nutrition significantly impacts organ development.
- Protein deficiency during critical developmental windows can have lasting physiological consequences.
Purpose of the Study:
- To investigate the effects of neonatal protein deficiency on rat lung development and function.
- To assess changes in lung cellularity, mechanics, and structural integrity.
Main Methods:
- Newborn rats were subjected to varying protein-restricted diets during lactation.
- Body weight, lung-to-body weight ratio, and lung cellular content were measured.
- Excisised lungs underwent air and saline-filling to assess volume-pressure curves, compliance, and rupture pressure.
Main Results:
- Protein deficiency led to decreased body weight gain and reduced lung DNA and protein content, indicating fewer and smaller lung cells.
- Air-filling volume-pressure curves showed decreased lung compliance in malnourished rats.
- Saline-filling revealed reduced recoil pressure, while rupture pressure increased in protein-deficient lungs.
Conclusions:
- Neonatal protein deficiency alters lung development, affecting both cellular composition and mechanical properties.
- The study suggests increased surface forces and tissue elastic forces, along with augmented lung rupture resistance, in malnourished lungs.
- These findings highlight the critical role of adequate protein intake during early life for normal lung development and function.
Abstract:
The effects of early protein-deficiency on lung development were studied in the rat. Newborn male rats were nursed in groups of eight. Control dams and pups received a 15% protein diet during the whole experiment. Test mothers only received 12 and 8% proteins from the 7th and the 14th day of lactation. Test rats fed a diet of 8% protein were weaned at 21 days and maintained on the low protein diet for 1 month. This caused a marked decrease in body weight gain, but lung/body weight ratio was not affected. Lung DNA and protein content, lung protein concentration, but not lung DNA concentration were decreased, suggesting the presence of fewer and smaller cells than in control lungs. Volume-pressure curves were performed on excised lungs. With air-filling, the curve obtained in rats fed a diet with 8% proteins was shifted downward and to the right, even when expressed as percent of maximal volume. Its exponential analysis assessed a decrease in lung compliance. In contrast, with saline-filling, the recoil pressure was decreased in rats fed a diet with 8% proteins. Both with air and saline-filling, the pressure at lung rupture was increased in malnourished rats. It is concluded that protein-deficiency from the neonatal period increases surface forces, decreases tissue elastic forces, and augments resistance of the lung to rupture.