Abstract
BACKGROUND: Cigarette smoke (CS) exposure during gestation may increase the risk of bronchopulmonary dysplasia (BPD)-a developmental lung condition primarily seen in neonates that is characterized by hypoalveolarization, decreased angio-genesis, and diminished surfactant protein production and may increase the risk of chronic obstructive pulmonary disease.
OBJECTIVE: We investigated whether gestational exposure to secondhand CS (SS) induced BPD and sought to ascertain the role of nicotinic acetylcholine receptors (nAChRs) in this response.
METHODS: We exposed BALB/c and C57BL/6 mice to filtered air (control) or SS throughout the gestation period or postnatally up to 10 weeks. Lungs were examined at 7 days, 10 weeks, and 8 months after birth.
RESULTS: Gestational but not postnatal exposure to SS caused a typical BPD-like condition: suppressed angio-genesis [decreased vascular endothelial growth factor (VEGF), VEGF receptor, and CD34/CD31 (hematopoietic progenitor cell marker/endothelial cell marker)], irreversible hypoalveolarization, and significantly decreased levels of Clara cells, Clara cell secretory protein, and surfactant proteins B and C, without affecting airway ciliated cells. Importantly, concomitant exposure to SS and the nAChR antagonist mecamylamine during gestation blocked the development of BPD.
CONCLUSIONS: Gestational exposure to SS irreversibly disrupts lung development leading to a BPD-like condition with hypoalveolarization, decreased angio-genesis, and diminished lung secretory function. Nicotinic receptors are critical in the induction of gestational SS-induced BPD, and the use of nAChR antagonists during pregnancy may block CS-induced BPD.