Neural plasticity occurs in the adrenal medulla of asthmatic rats.

BACKGROUND

Airway symptoms in asthma are related to decrease of epinephrine secretion, which may be ascribed to elevated nerve growth factor (NGF) in the organism. The aim of this study was to monitor the neuroendocrine alteration in the adrenal medulla of asthmatic rats.

METHODS

Sixteen rats were randomly divided into two groups (n = 8), control group and asthma group, and the asthmatic rats were sensitized and challenged with ovalbumin (OVA). The levels of NGF, epinephrine and norepinephrine in serum were detected by enzyme linked immunosorbent assay (ELISA), the NGF expression in adrenal medulla was detected by immunohistochemistry, and the changes in the ultrastructure of the adrenal medulla was observed by electron microscopy.

RESULTS

The NGF expression was increased in asthmatic rats compared with control rats. Compared with control rats, the results indicated that the epinephrine level was decreased in asthmatic rats, but no significant difference was found in norepinephrine levels. We found more ganglion cells in the adrenal medulla of asthmatic rats than in control rats, with NGF immunostaining mainly located in these ganglion cells. Electron microscopic images showed the density of chromaffin granula decreased and there was shrunken nucleolemma in the adrenal medullary cells of asthmatic rats.

CONCLUSION

The innervation of the adrenal medulla is changed in asthmatic rats, and it may contribute to the epinephrine decrease in asthma.