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[Early changes of postpneumonectomy lung growth in premature rats]
T Mizuuchi1, K Kida, T Taguchi
1Pulmonary Division, Tokyo Metropolitan Geriatric Hospital, Japan.
Insights
Pneumonectomy in premature rats shows compensatory lung growth. The contralateral lung rapidly increases in weight and volume, with early cellular hyperplasia, indicating significant regenerative capacity in immature lungs.
Area of Science:
- Pulmonary Medicine
- Developmental Biology
- Regenerative Medicine
Context:
- Pneumonectomy (lung removal) triggers compensatory lung growth in adult animals.
- Immature animals' response to pneumonectomy, combining normal growth and regeneration, is poorly understood.
- Previous studies highlight age-dependent differences in lung regeneration post-pneumonectomy.
Purpose:
- To investigate early morphological and biochemical changes in the contralateral lung after pneumonectomy in premature rats.
- To elucidate the effects of pneumonectomy on lung growth and cellular proliferation in very young mammals.
- To compare compensatory lung growth dynamics in immature versus mature animal models.
Summary:
- Following left pneumonectomy in 2-week-old rats, the contralateral lung's wet weight matched controls within one week, and fixed volume by three weeks.
- Increased DNA polymerase activity and bromodeoxyuridine (BrdU)-positive cells were observed early post-pneumonectomy, indicating heightened cell proliferation.
- DNA content reached control levels by four weeks, suggesting cellular hyperplasia contributes to compensatory lung growth in immature rats.
Impact:
- This study provides crucial insights into the regenerative potential of immature lungs following significant injury or resection.
- Findings may inform therapeutic strategies for lung conditions in premature infants or pediatric patients requiring lung surgery.
- Establishes a model for studying early-stage compensatory lung growth and hyperplasia in a neonatal setting.
Abstract:
Following pneumonectomy in animals, the contralateral lung increases in volume, weight, collagen content, protein, and cell number, reaching levels approximate to those of both lungs of control animals. The volume and weight response in quicker and more complete in young animals compared to old animals. The increase in the amount of DNA was found to be greater in young rats compared to old ones. However, little is known about the effects of pneumonectomy in immature animals, in which combined effects of normal and the compensatory lung growth may be expected. The present studies were aimed at elucidating early changes in terms of morphology and biochemistry in the contralateral lung following pneumonectomy in premature rats. Male Sprague-Dawley rats (2 week-old) were subdivided into 3 groups. Group P, underwent left pneumonectomy, group S was sham operated, which group C was matched by age, sex, and weight with group P. Morphological studies consisted of light microscopic morphometry and immunohistochemistry using anti-bromodeoxyuridine (BrdU) were performed. Biochemical studies included measurement of DNA polymerase activity, DNA and RNA content, collagen and elastin content. The wet lung weight in group P after one week reached approximately the same as that of bilateral lungs of groups S and C. The fixed lung volume of group P reached that of group S or group C at three weeks. The activity of DNA polymerase and BrdU positive alveoli were increased only during the early period following pneumonectomy. DNA content in group P reached the same range as group S and C at 4 weeks, suggesting the occurrence of cellular hyperplasia.(ABSTRACT TRUNCATED AT 250 WORDS)