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Lung morphometry and MMP-12 expression in rats treated with intraperitoneal nicotine
Samuel Santos Valença1, Adenilson de Souza da Fonseca, Katia da Hora
1Department of Histology and Embryology, Institute of Biology Roberto Alcantara Gomes, State University of Rio de Janeiro, Rio de Janeiro, Brazil.
Summary
Nicotine exposure causes significant lung damage, including alveolar septal thickening and inflammation. Even after recovery, Wistar rats showed progressive morphological damage, highlighting nicotine
Area of Science:
- Pulmonary Pathology
- Toxicology
- Morphometry
Background:
- Nicotine is a key toxic component in tobacco smoke.
- Nicotine is implicated in the development of cardiovascular and lung diseases.
- Understanding nicotine's impact on lung morphology is crucial for public health.
Purpose of the Study:
- To investigate the effects of intraperitoneal nicotine administration on rat lung morphology.
- To assess changes in alveolar parenchyma, elastic fibers, and microvasculature.
- To evaluate the expression of macrophage metalloelastase (MMP-12) following nicotine treatment.
Main Methods:
- Wistar male rats received daily intraperitoneal injections of nicotine (1 mg/kg) for 8 days.
- Lung tissues were analyzed at 24, 48, 96, and 192 hours post-treatment.
- Morphometry, immunohistochemistry for MMP-12, and alpha-smooth muscle actin staining were employed.
Main Results:
- Nicotine induced alveolar septal thickening, mononuclear cell infiltration, angiogenesis, and lung collapse.
- Increased alveolar parenchyma volume fraction and microvasculature density were observed.
- Reduced volume and surface fraction of septal elastic fibers and MMP-12 expression in macrophages were noted.
Conclusions:
- Intraperitoneal nicotine exposure leads to significant and progressive lung morphological damage.
- Inflammation, fibrosis, and altered microvasculature persist even after a recovery period.
- Nicotine's detrimental effects on lung structure underscore the risks associated with tobacco use.