[Relationships between melatonin and cortisol and the status of disease in patients with bronchial asthma]

The aim of the study was to elucidate the interaction and clinical significance between melatonin and cortisol and the status of disease in patients with bronchial asthma.

Ten mild persistent and 10 moderate-to-severe persistent asthma patients were recruited to participate in the study. Fifteen normal subjects served as contrds Salivary free melatonin and cortisol were measured simultaneously by radioimmunoassay in all subjects, and 8 salivary samples were collected in a series during a 24-hour period in each subject. The intensity of light was restricted to natural light at room during the daytime and less than 50 lux at night.

The results showed that salivary free melatonin levels were significantly lower in mild (15.5 +/- 5.3) micro g/L and moderate-to-severe (7.1 +/- 2.5) micro g/L persistent asthma patients as compared to control subjects (28.9 +/- 8.7) micro g/L (F = 4.47, P < 0.05; F = 7.61, P < 0.01, respectively). The results also showed that salivary free cortisol levels were significantly lower in mild (3.1 +/- 0.5) micro g/L and moderate-to-severe (4.2 +/- 0.5) micro g/L persistent asthma patients as compared to control subjects (5.9 +/- 0.7) micro g/L (F = 10.45, P < 0.01; F = 5.21, P < 0.05, respectively). The amplitude of salivary free cortisol level was reduced in mild and moderate-to-severe persistent asthma patients, and salivary cortisol peak level was significantly delayed in mild and moderate-to-severe persistent asthma patients (P < 0.05, P < 0.01, respectively). There were no significant correlations between the salivary free melatonin and cortisol levels in control and mild persistent asthma patients (r = 0.174, P = 0.057; r = -0.138, P = 0.221, respectively). However, a significant negative correlation was found between the salivary free melatonin and cortisol levels in moderate-to-severe persistent asthma patients (r = -0.275, P = 0.013).

There were lower salivary free melatonin and cortisol levels in asthmatic patients. A significant negative correlation was found between melatonin and cortisol levels in moderate-to-severe persistent asthma patients. Furthermore, the reciprocal inhibition of melatonin and cortisol was closely associated with the status of disease in asthmatic patients.