[The distribution of substance P in the lungs of asthmatic guinea-pigs and the influence of dexamethasone on the distribution].

OBJECTIVE

To investigate the distribution of substance P(SP) in the lungs of asthmatic guinea pigs and the effects of dexamethasone on its distribution.

METHODS

Guinea pigs were divided into 3 groups: asthma group, dexamethasone-treated group and control group. Rabbit serum against SP, immunohistochemical ABC method and glucose-DAB-nickel technique for staining and computer image analysis were used in this study.

RESULTS

There was distribution of SP-IR positive fibres in airways in asthma group than the other two groups. The positive fibres, emerged like a string of beads, were present as large fibre bundles in the smooth muscle layer and basement membrane. Additionally, in the asthma group SP-IR positive fibres were detected on the walls of respiratory bronchioles and alveolar ducts in contrast to the other groups. There was no difference in distribution and morphological characteristic between the control group and the dexamethasone-treated group.

CONCLUSION

Repeated antigen challenges, which cause the allergic inflammation of airways, may result in the growth of SP-containing nerve fibres in the airway and synthesis of SP in neurons. These may be involved in the persistence and exacerbation of airway inflammation in asthma. Dexamethasone can reverse the distribution of SP-IR positive fibres to the normal status in airway walls of asthma guinea pigs.