The investigation of effect of alpha lipoic acid against damage on neonatal rat lung to maternal tobacco smoke exposure

This study was carried out to determine the histological and biochemical changes in the lungs of the rat pups exposed to tobacco smoke during pregnancy period and to investigate the protective effects of alpha lipoic acid, which is administered during pregnancy, on these changes. In our study, 24 six-week old Spraque-Dawley female rats weighing 160 ± 10 g were used. Female rats were mated with male rats and the date on which the sperm was observed in the vaginal smear was considered as the embryonic day zero. The pregnant rats were randomly divided into four equal groups: group I (control), group II (tobacco smoke), group III (tobacco smoke + alpha lipoic acid) and group IV (alpha lipoic acid). The female rats in the group II, group III were exposed to tobacco smoke twice a day for one hour starting from eight weeks before mating and during pregnancy. In addition to tobacco smoke, 20 mg / kg of alpha lipoic acid was administered via oral gavage to the rats in the group III. Only 20 mg / kg of alpha lipoic acid was administered to the rats in the group IV via oral gavage during the stated period of time. Once after the delivery, all administrations were stopped. On postnatal days 7 and 21, seven pups were taken from each group and their body weights were weighed. At the end of the experimental period, the pups in all groups were decapitated. The lungs of the rats were removed and weighed. A portion of the lung was taken and passed through routine histological follow-up series. The obtained preparations were stained with the triple paint of H & E, PAS and Masson. In addition to immunohistochemical staining of surfactant protein A (SP-A), vascular endothelial growth factor (VEGF), caspase-3, TUNEL method was also used to determine apoptosis. Biochemical analyzes were performed with some part of the lung tissue specimens. A significant decrease was observed in the weights of 7-day old postnatal rats of the tobacco smoke group compared to the control group (p <0.05). No significant difference was found between the other groups. Relative lung weights of the tobacco smoke group were found to be significantly increased compared to the control group (p <0.05) whereas that of the tobacco smoke + ALA group was significantly decreased compared to the tobacco smoke group (p <0.05). No statistically significant difference was observed in the body weights and relative lung weights of 21-day old postnatal rats of the tobacco smoke group compared to the control group (p>0.05). In the histological evaluations performed under light microscopy, inflammatory cell increase, hemorrhagic areas, edema, interalveolar septal thickening, degeneration of some bronchi and bronchial epithelium, epithelial cells that were fallen into the lumen and hyaline membrane formation were observed in the lung sections from 7- and 21-day old postnatal rats of the tobacco smoke group compared to the control group. These histopathological findings were observed to be decreased in the lung sections of the tobacco smoke + ALA group (p <0.05). Hyaline membrane formation was not detected in this group. In morphometric measurements performed with the RAC method, the alveolar numbers in the lung sections from 7- and 21-day old postnatal rats of the control and ALA groups were observed to be close to each other (p> 0.05). A statistically significant decrease was found in the alveolar numbers of the tobacco smoke group when compared to the control group (p <0.05). There was a statistically significant increase in the alveolar numbers in the tobacco smoke + ALA group compared to the tobacco smoke group (p <0.05). The TUNEL positive cell numbers in the lung tissues from 7- and 21-day old postnatal rat groups were similar in the control group and ALA group (p> 0.05). When compared with the control group, a significant increase was detected in the tobacco smoke group (p <0.05). A significant decrease was detected in the tobacco smoke + ALA group when compared with the tobacco smoke group (p <0.05). In terms of the immunoreactivity of both SP-A and VEGF in the lung tissues from 7 and 21-day old postnatal rats, a significant decrease was observed in the tobacco smoke group compared to the control group (p <0.05) and a significant increase was observed in the tobacco smoke + ALA group compared to the tobacco smoke group(p <0.05). Regarding the immunoreactivity of caspase-3, there was a statistically significant increase in the group of tobacco smoke compared to the control group (p <0.05) and a significant decrease in the group of tobacco smoke + ALA compared to the group of tobacco smoke (p <0.05). The malondialdehyde (MDA) levels in the lung tissue samples from 7 and 21-day old rats were determined to be significantly increased in the tobacco smoke group compared to the control group (p <0.05) and they were determined to be significantly decreased in the tobacco smoke + ALA group compared to the tobacco smoke group(p <0.05). Glutathione (GSH) levels and superoxide dismutase (SOD) enzyme activities showed a significant decrease in the group of tobacco smoke compared to the control group (p <0.05) and a statistically significant increase in the tobacco smoke + ALA group compared to the group of tobacco smoke (p <0.05) In conclusion, when the results of our study are evaluated together, we suggest that the exposure of tobacco smoke during pregnancy leads to morphological, histopathological and functional changes on lung development by causing oxidative damage in lung tissues of neonatal rats and the maternal use of alpha lipoic acid, which is known to have strong antioxidant properties, can provide a protective effect on the neonatal lung development against this oxidative stress originating from tobacco smoke.