Expression of melatonin receptors in the gastroesophageal reflux disease associated with obstructive sleep apnea/hypopnea syndrome
The aim of the present research was to assess the expression of melatonin receptors (MTNR1B) in the esophageal mucosa in the gastroesophageal reflux disease associated with obstructive sleep apnea/hypopnea syndrome and to study the relationship between the detected changes and the sleep apnea severity. 84 patients aged 30–60 years, including those with gastroesophageal reflux disease (group 1, n = 25), those with gastroesophageal reflux disease associated with sleep apnea/hypopnea (group 2, n = 23), those with obstructive sleep apnoe/ hypopnoe syndrome (group 3, n = 18), and almost healthy people (group 4, n = 18), were studied. Diagnoses were based on endoscopic imaging and respiratory monitoring. The MTNR1B expression in the esophageal mucosa was determined by the immunohistochemical method using specific antibodies. The MTNR1 B expression was evaluated quantitatively using the computer program Aperio ImageScope _v9.1.19.1567. The obtained material was analyzed statistically using the software Statistica 10.0. The group 2 patients were shown to have a higher MTNR1B expression compared to the group 1 patients (0.122 [0.064; 0.266] versus 0.620 [0.332; 0.983]; p = 0.00001) and the group 3 patients (0.620 [0.332; 0.983] versus 0.232 [0.120; 0.418]; р = 0.0098). The MTNR1 B expression increased with growing sleep apnea severity: it is 0.295 [0.198; 0.403] in patients with mild apnea versus 0.941 [0.345; 0.992] in patients with moderate and severe apnea (p = 0.0021). A direct correlation between the MTNR1B expression and the sleep apnea severity degree (r = 0.50; р = 0.0016) was revealed. Patients with gastroesophageal reflux disease combined with sleep apnea revealed an increase in the MTNR1 B expression associated with the apnea severity. The revealed features of the MTNR1 B expression secondary to esophageal mucosal damage indicate the MTNR1 B inactivation secondary to accompanying apnea of hypoxia.