Melatonin – the sleep hormone – makes asthma worse: Study | Photo credit: iStock Images
Sendai: A study led by Kentaro Mizuta of Tohoku University Graduate School of Dentistry found that the sleep hormone melatonin makes asthma worse. The research was published in the American Journal of Lung Cellular Physiology and Molecular Physiology.
Asthma sufferers have bronchoconstriction, which is the contracture of the smooth muscles of the bronchus – the pathway that carries air to and from the lungs. To relieve this, many take a bronchodilator, a medicine that dilates the bronchi. Melatonin, however, which is often prescribed for insomnia, favors a state of bronchoconstriction and weakens the relaxing effects of a bronchodilator by activating the melatonin MT2 receptor.
To shed light on this, the research group identified the expression of the melatonin MT2 receptor in the smooth muscles of the human respiratory tract. They observed that activation of the melatonin MT2 receptor with higher doses of melatonin or the melatonin receptor agonist Ramelteon greatly increased bronchoconstriction. In addition, melatonin weakened the relaxing effects of the widely used bronchodilator b-adrenoceptor agonist.
“Although serum levels of melatonin did not significantly induce airway constriction, higher doses of melatonin, which is clinically used to treat insomnia, jet lag, or cancer, worsened asthma symptoms and impaired the therapeutic effects of bronchodilators,” Mizuta said.
First author of the paper, Haruka Sasaki added, “Pharmacological therapy that blocks the melatonin MT2 receptor could inhibit the harmful effects of melatonin on the airways.”