Effects of perinatal nicotine exposure on the development of albino rat's alveoli with special reference to the role of the vascular endothelial growth factor

ABSTRACT

Nicotine is one of the most toxic and addictive agents in cigarette smoke. Maternal cigarette smoking may affect lung development and maturation of the fetus. Recently, it has been reported that blood vessels promote alveolar growth during development and contribute toward the maintenance of alveolar structures throughout postnatal life. The aims of this study were to determine the effects of perinatal nicotine exposure on the histological structures of the developing alveoli of offspring with special reference to the role of vascular endothelial growth factors [VEGF]. Ten healthy pregnant rats were divided equally into control [I] and treated [II] groups. Rats of group II were subjected to a daily subcutaneous injection of 1 mg/kg of nicotine from the seventh day of gestation until the end of the experiment. Their offspring were subdivided into two subgroups at 2 and 21 postnatal days. At the time of sacrifice, all rats were anesthetized with ether and lung samples were processed for light and electron microscopic examination. Also, an immunohistochemical study was carried out for VEGF. The alveolar diameter, thickening of interalveolar septa, number of vacuolated interstitial cells, and the surface area of VEGF immunoexpression were determined and analyzed statistically. In the nicotine-exposed groups, widening in alveoli and thinning of interalveolar septa in the offspring were observed. Also, the same offspring showed a reduction in VEGF immunoexpression. All these results were confirmed statistically especially at 3 weeks of age or at the time of weaning. Also, swelling in pneumocyte type I and deformed blood air barriers with a subsequent statistical increase in the number of vacuolated interstitial cells [pneumocyte type II] were observed. In the current work, it was found that perinatal exposure to nicotine altered lung development, an effect that may be mediated by decreased VEGF. Thus, avoidance of maternal smoking during pregnancy and lactation is highly recommended