Maternal nicotine induces collagen type IV changes and its role on pulmonary bronchogenesis and alveolarization in mouse newborns

Nicotine is one the chemical substance by high level of toxically which can rapidly absorbed from the lungs of smokers. It crosses the placenta and accumulates in the developing fetus. Our previous investigation indicated that collagen type IV appearance has a key role in basement membrane of various embryonic organs. We evaluated the effect of maternal nicotine exposure pre and postnatal period on collagen IV expression during bronchogenesis and alveolarization in the lung of mouse newborns. Pregnant Balb/C mice, were divided into 2 experimental and 2 control groups. Experimental group 1, received 3 mg/kg nicotine intrapritoneally from day 5 of gestation to last day of pregnancy. Experimental group 2 were received the same amount of nicotine during the same gestational days as well as 2 first week after birth (lactation). The control groups received the same volume of normal saline during the same periods. At the end of exposure times, all of newborns were anesthetized and their lungs were removed and immunohistochemical study for tracing collagen were carried out. Our finding indicated that collagen reaction in the bronchial basement membrane (BBM) and extra cellular matrix (ECM) of lung parenchyma in experimental groups increased significantly in compared to control groups. Our finding showed that an alveolar remodeling and abnormal bronchogenesis in experimental group especially group 2 were observed. These data indicate that maternal nicotine exposure may induces an abnormal collagen IV expression and cause a defect in bronchopulmonary development.