Comparison Of Ambroxol With Dexamethasone On The Expressions Of Pulmonary Surfactant Proteins In The Lung Of Fetal Rat

Objective: The neonatal respiratory distress syndrome(NRDS) caused by the difference of pulmonary surfactant is harmful to the health of newborns, especially to premature infants. So it is important to prevent the disease. Recently researches showed that glucocorticoid have a active role in promoting lung maturation and stimulating surfactant synthesis, but the side effects can bring harm to the pregnant women and fetus. Ambroxol is a kind of drug had the same role in promoting maturation of lung and stimulating surfactant synthesis as the glucocorticoid with little side effects. Many researchers use ambroxol for preventing NRDS, but its effects were not affirmative. To explore the effects of a maternally administered ambroxol and dexamethasone (Dex), the levels of mRNA of the surfactant proteins (SP-A,SP-B and SP-C) were researched in the fetal lung tissues of day 19 gestational age of rats. By comparing with the effects of glucocorticoid, we can know the effects of ambroxol.Methods: The rats of experiment were divided into three groups, including ambroxol-injected group , Dex-injected group and control group. The first group was injected ambroxol 100mg/(kg.d) to the pregnant rat for three days from day 16 to 18 pregnancy. The control was injected the saline whose volume was as well as the ambroxol-injected. The second group was injected Dex 2.0mg/(kg.d) on day 18 of pregnancy. All rats were sacrificed on day 19 of pregnancy, the fetuses were removed from the uterus and their lung tissues were isolated. Situ hybridization was used to detect the expression of SP-B mRNA in alveolar Ⅱtype cell, and the levels ofSP-A,SP-B and SP-C mRNAs were detected by semiquantitative reverse transcriptase-polymerase chain reaction(RT-PCR).Results: 1,In situ hybridization, SP-B mRNA in fetal rat of day 19 gestational age was detected in alveolar typeⅡcells and also present in bronchiolar epithelial cells. 2,In the ambroxol-injected group, the relative values of mRNA of SP-A,SP-B and SP-C were 1.04±0.17,1.28±0.29 and 1.09±0.26 in fetal lung tissues, respectively. In the Dex-injected group, the relative values of mRNA of SP-A, SP-B and SP-C were 1.08±0.23,1.23±0.35 and 1.21±0.25 in fetal lung tissues,respectively. In the control group, the relative values of mRNA of SP-A,SP-B and SP-C were 0.81±0.26,0.97±0.20 and 0.88±0.11 in fetal lung tissues, respectively. Compared the two interfering groups with the control group, F values was 6.167,8.399 and 8.949(P＜0.05),respectively.3,There was no significant difference in levels of increasing the expressions of mRNA of surfactant protein between ambroxol-injected group and Dex-injected group, t values were 0.587,0.399 and 1.071, respectively(P＞0.05).Conclusions:1,Dex play a active role in the expression of surfactant protein mRNA.. 2,Ambroxol can also caused a significant increasing in the expression of surfactant genes. 3,Compared with Dex, ambroxol can get to the similar effects on increasing the expressions of surfactant protein genes. So we can assume that it is possible to prevent the respiratory distress syndrome of newborn by administration ambroxol instead of glucocorticoids.