| Premature delivery is a common obstetrical complication, which accounts for nearly 7% tolO% in all the pregnancies. In the premature, the morbidity and mortality of Neonatal Respiratory Distress Syndrome are increased dramatically. This is mainly because of the immature fetal lung structure and function, which lead to the lack of surfactant. It is highly concerned as to how to increase the survival rate of the premature and reduce the occurrence of NRDS. Hitherto, a lot of research have been focused on the mechanism of fetal lung development and have achieved many findings. It has been recognized that growth factors play important role in the maturation of fetal lung through autocrine and paracrine paths. And Latest researches have demonstrated that, Leptin is closely correlated with fetal growth and development and probably influence the development of fetal lung and the production of lung surfactant as a paracrine growth factor.Leptin, a 16-kDa product of the obesity gene, is produced by adipose cell or lipofibroblast. Some recent researches demonstrate that leptin is related with gestation and fetal development. The serum leptin level of umbilical arteries is shown to be greatly concerned with the birth weight of the newborns. Moreover, leptin receptors are found expressed in many fetal organs such as brain, liver kidney and so on. What's interesting is that leptin has many characteristics in common with FPF, such as cell origin, molecular weight. All the above implies that leptin may just the FPF we have been searching for a long time. In this ex-periment, we test the expression of leptin in fetal rat lung and the influence of Dexamethasone on fetal lung fibroblast leptin expression to disclose the complicated mechanism of fetal lung development.Materials and methods1. AnimalsIn order to get time-mated Wister rats (embryonic day0, E, the day of mating) , we selected adult fertile rats of two months old weighing between 230 ~ 260 g from the Experimental Animals Breeding Department of China Medical U-niversity and raised them under same standard conditions. Every morning, we i-dentified the pregnant rats through detecting sperms on vaginal smears.2. Tissue sampleIn the last third of gestation, tissue samples of fetal rat lung were collected at different gestational ages (from E 16 to E21) and stored under-70 to be tested for leptin expression by RT-PCR. The dams were killed with an overdose of Chloral hydrate, and the pups were removed from the uterus by laparotomy and kept on ice. The lungs were removed en bloc.3. Primary culture of lung fibroblastThe fetal lung tissues were treated by 0. 25% trypsin for 20 ~ 30 minutes when the tissue had been completely dispersed in a unicellular suspension, the cells were spun down and the cell pellet was resuspended in DMEM containing 10%FBS. The cell suspension was added to culture flasks for 40 ~60minutes to allow differential adherence of fibroblasts. The unattached cells in supernatant were discarded. Fibroblasts were maintained in DMEM until further processing. Confluent monolayer culture of fibroblast was treated with dexamethasone. 24 hours later, cells were collected and stored under -704. SemiquantitativeRT-PCRRNA acquired from tissues and cells collected above were used for RT-PCR.5. Statistics analysisData are expressed as the means ?SEM. Independent-sampled and paired-sampled t test were respectively used for the analysis of data from tissue and cell samples. Difference were considered statistically significant for P < 0.05.Results1. Leptin is expressed in all the tissue samples collected in our experiment and the expression increase gradually in E16 - E17 ,E18 - E19 and E20 -21, which corresponds to the transition from glandular to canalicular and saccular stage of fetal rat lung development.2. After being treated by dexamethasone(l x 10-8 M) , a widely used drug ifi clinical practice to accelerate the maturation of fetal lung, for 24 hours, the expression of leptin in cultured lung fibr...
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