Influence of exogenous pulmonary surfactant on asthma attack and epidermal growth factor in rats

Haifeng OUYANG; Diantao NI

ABSTRACT

BACKGROUND:

There are reports that exogenous pulmonary surfactant (PS)participating in acute asthma attacks in rats with asthma and has correlation with epidermal growth factor(EGF) and expression of EGFmRNA.

OBJECTIVE:

To observe the effect of PS on EGF and EGFmRNA in asthmatic rats.

DESIGN:

Controlled experimental study on experimental animals.

SETTING:

Respiratory departmentof a military medical university affiliated hospital.MATERIALS The experiment was completed in Laboratory 2 of Experiment Animal Center; Immunohistochemistry Laboratory, Department of Pathology of Fourth Military Medical University of Chinese PLA from April 2004 to July 2004. Sixty male SD rats weighting 100 - 120 g were provided by the Experiment Animal Center of the Fourth Military Medical University of Chinese PLA. The animals were randomly divided into 3 groups, that is normal control group, asthma control group(asthma group) and PS treatment group (treatment group) with 20 rats in each group.

METHODS:

The models of asthmatic rats were established. 1mL of immunogen stock suspension and 1 mL trachitis vaccine were injected intraperitoneally into the rats in the asthma group and treatment group respectively, and the normal control group were treated with the same volume of saline. Two weeks after being allergic, 10 g/L oval bumin were given to the asthma group and treatment group. The normal control group was given saline ultrasonic nebulization for 20 minutes; the treatment group was performed atomizing inhalation PS 100 mg/kg driving by oxygen before each provocation. The expression of EGF was detected with immunohistochemistry and the expression of EGF mRNA was detected with reverse transcription-polymerase chain reaction (RT-PCR).MAIN OUTCOME

MEASURES:

The onset condition of the rats in each group and the comparison of the level of EGF and the expression of EGFmRNA in lung tissue of the bronchus.RUSULTS There were 20 rats entered the result analysis in each group. Onset rate of asthma in asthma group [90% (18/20) ] was higher than that in the treatment group[5% ( 1/20) ] (x2 = 28.97, P ＜ 0.01 ). The image analysis of the EGF expression showed that the absorbance in the asthma group(9. 652 ± 1. 086) was higher than that in the normal control group (3. 267 ± 0. 986) ( t = 18. 552, P ＜ 0.01 ). The absorbance in the treatment group(4. 132 ± 1. 012) was similar to that in the control group( P ＞ 0.05);The electrophoresis bands of mRNA amplified products in each group showed that in the normal control group the expression was weak and it was strong in the asthma group. The expression in the treatment group was obviously weaker than that in the control group.

CONCLUSION:

Exogenous PS can reduce the onset of asthma and its mechanism might be related with inhibiting the synthesis and release of EGF.