Perinatal expression of HSP70 and VEGF in neonatal rat lung vessels exposed to nicotine during gestation

We assessed the influence of maternal nicotine exposure during gestation on perinatal expression of HSP70 and VEGF in rat lung parenchyma and lung vessels. Adult white Sprague-Dawley virgin rats were mated with adult male rats over 2 days, with two females for every male. After confirming pregnancy, 30 gravid rats (dams) were then randomly assigned to two equal groups (one experimental and one control; n=15 in each). Experimental dams were treated with subcutaneus (s.c.) (-)-nicotine tartrate, 3 mg/kg body weight/day, during pregnancy from gestational days 9 through 21. After sacrifice, lungs were removed en bloc and formalin-fixed, and paraffinembedded tissue sections were evaluated by immunohistochemistry using a three-step streptavidin-biotin-peroxidase method with monoclonal antibodies directed against HSP70 or VEGF. HSP70 and VEGF expression was increased in the vascular smooth muscle cells of the experimental group (t1) compared to the control group (t(2))t(1)=7.593, t(2)=4.666, p < 0.05). The number of bronchioles that stained positively with HSP70 was higher in the nicotineexposed group than in the control group (t(1)=9.274, t(2)=6.956, p < 0.05). In conclusion, gestational nicotine exposure increased the expression of VEGF and HSP70 in rat lung parenchyma, especially in the airway epithelium and vascular smooth muscle cells. In vascular smooth muscle cells, these molecules may contribute to nicotine-related hypoxic pulmonary hypertension.