Morphological changes in lungs, placenta, liver and kidneys of pregnant rats exposed to cigarette smoke

Abstract

Objective. Histopathological examination of changes in foetal and newborn rats, and histopathological and morphometric assessments of changes in lungs, placenta, liver and kidneys of adult rats exposed to cigarette smoke were performed.

Methods. Non-pregnant and pregnant Wistar female rats were exposed to cigarette smoke at a carbon monoxide concentration of 1,500 mg/m³ for 6 h per day, 5 days per week, for 3 weeks. Levels of urine nicotine and cotinine were used as measures of exposure. Paraffin-embedded, haematoxylin and eosin (HE)-stained sections were used for examination. Morphometry of studied organs was performed using a computer image analyser.

Results. Applied smoke dose and exposure time produced dramatic histopathological changes in lungs of exposed rats (emphysema, emphysematous, inflammatory, metaplastic changes) and reduction in height of respiratory-bronchiole epithelium, and considerably less-marked morphological changes in hepatic (number of apoptotic hepatocytes) and renal (height of proximal convoluted tubule epithelium) cells as well as in the placenta (for example, size of giant cells in labyrinth, height of epithelium covering yolk sac ). Exposure to cigarette smoke did not result in histopathological changes in lungs and liver of surviving foetuses. The duration of pregnancy was not changed but a tendency for a decrease in the mothers' fertility indices as well as some changes in foetal and newborn parameters was observed.

Conclusion. Taking into account the morphological changes observed in adult rat tissues and placentae which can result in definite hormonal and trophic effects on the foetus, the possibility of early or late physiological effects in progeny under the influence of cigarette smoke must be taken into consideration.