Abstract
Background: Decreased epinephrine (EPI) is an important underlying factor of bronchoconstriction in asthma. Exogenous β(2)-adrenergic receptor agonist is one of the preferred options to treat asthma. We previously showed that this phenomenon involved adrenal medullary chromaffin cell (AMCC) transformation to a neuron phenotype. However, the underlying molecular mechanism is not fully understood. To further explore this, an asthmatic model with unilateral adrenalectomy was established in this study. Methodology/principal findings: Thirty-two rats were randomly into four groups (n = 8 each) control rats (controls), unilateral adrenalectomy rats (surgery-control, s-control), asthmatic rats (asthma), unilateral adrenalectomy asthmatic rats (surgery-induced asthma, s-asthma). Asthmatic rats and s-asthmatic rats were sensitized and challenged with ovalbumin (OVA). The pathological changes in adrenal medulla tissues were observed under microscopy. EPI and its rate-limiting enzyme, phenylethanolamine N-methyl transferase (PNMT), were measured. Peripherin, a type III intermediate filament protein, was also detected in each group. The asthmatic rats presented with decreased chromaffin granules and swollen mitochondria in AMCCs, and the s-asthmatic rats presented more serious pathological changes than those in asthmatic rats and s-control rats. The expressions of EPI and PNMT in asthmatic rats were significantly decreased, as compared with levels in controls (P<0.05), and a further decline was observed in s-asthmatic rats (P<0.05). The expression of peripherin was higher in the asthmatic rats than in the controls, and the highest level was found in the s-asthmatic rats (P<0.05). Conclusion/significance: Compared with asthmatic rats and s-control rats, the transformation tendency of AMCCs to neurons is more obvious in the s-asthmatic rats. Moreover, this phenotype alteration in the asthmatic rats is accompanied by reduced EPI and PNMT, and increased peripherin expression. This result provides further evidence to support the notion that phenotype alteration of AMCCs contributes to asthma pathogenesis.