Study explains why melatonin may exacerbate the effects of asthma

According to new findings in the American Journal of Physiology-Lung Cellular and Molecular Physiology, the sleep hormone melatonin may worsen the symptoms of asthma.

The outcome of its use may include constriction of the bronchus, known as bronchoconstriction, in which a bronchodilator is often used to widen the bronchus.

Based on the study, a team of Japanese and American researchers explained that the activation of the melatonin MT2 receptor steers away from any potential beneficiary effects from a bronchodilator, increasing the severity of bronchoconstriction.

“We investigated whether melatonin receptors are expressed on airway smooth muscle; whether they regulate intracellular cyclic AMP (cAMP) and calcium concentrations ([Ca2+]i), which modulate airway smooth muscle tone; and whether they promote airway smooth muscle cell proliferation,” the authors of the study elucidated in their report.

“Although melatonin by itself did not induce an initial [Ca2+]i increase and airway contraction, melatonin significantly potentiated acetylcholine-stimulated [Ca2+]i increases, stress fiber formation through the MT2 receptor in HASM cells, and attenuated the relaxant effect of isoproterenol in guinea pig trachea,” the authors also explained.

“These findings suggest that the melatonin MT2 receptor is expressed in ASM, and modulates airway smooth muscle tone via reduced cAMP production and increased [Ca2+]i.”

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