Melatonin and omentin: influence factors in the obstructive sleep apnoea syndrome?

The incidence of the obstructive sleep apnoea syndrome (OSAS) is rising as it is often associated with obesity. Actually, the adipose tissue is working as an endocrine organ with complex interactions. Recently, many adipokines such as omentin-1 were discovered. The role of omentin-1 in the pathogenesis of OSAS has not been clearly determined. Melatonin has a known influence on the sleep and wake rhythm. The data on the involvement of melatonin in OSAS are rare. Therefore we evaluated the changes in plasma levels of omentin-1 and melatonin before and after continuous positive airway pressure (CPAP) therapy in OSA patients. 10 patients with newly diagnosed OSAS were included in the study. They underwent diagnostic polysomnography with blood drawings in a 2 hour interval for 24 hours. In the second night sufficient CPAP therapy was established. After three months of CPAP therapy the measurements were repeated. As controls 10 healthy volunteers were recruited. The same blood analysis and a polygraphic measurement were made and compared with the patients. OSA patients showed significantly higher omentin-1 plasma levels (17.22±13.94 versus 9.24±4.85 ng/ml, p<0.05). After three months of therapy the plasma levels of omentin-1 decreased toward the values observed in the controls at 8.00 a.m. Melatonin showed the usual peak at 2.00 a.m. in the volunteer group. OSA patients showed a later peak of melatonin at 6.00 a.m. which returned to 2.00 a.m. after CPAP therapy. We conclude that omentin as well as melatonin seem to be involved in pathogenesis of OSAS. To what exent, further studies will have to face that question.