Endocrine Abstracts

Melatonin has a key role in circadian timing system. At present, many other functions of melatonin are known. It shows a remarkable functional versatility exhibiting antioxidant (direct free radical scavenging and indirect antioxidant activities), oncostatic, anti-aging, immunomodulatory properties and many other functions. In addition to pineal gland, gastrointestinal tract is the second biggest source of melatonin. Question remains whether changes in endogenous melatonin may be influenced by food intake. In our previous study, melatonin negatively correlated with C-peptide and glucose after food intake during daytime. For the better understanding of the possible role of melatonin as a factor, which can be influence food intake, we monitored levels of melatonin, C-peptide and blood glucose after different food stimulus. Five women (mean age 31.6±2.8 years, mean BMI 23.2±2.3 kg/m² in follicular phase of menstrual cycle) were examined. All of them had standard intravenous glucose toleration test, standard oral glucose toleration test, standard breakfast (standard ratio of fat, carbohydrates and proteins) and non-caloric stimuli (psyllium). Variation in C-peptide levels was followed by changes of melatonin levels and also mechanic stimuli of food intake had the same effect on melatonin levels. Negative relationship between melatonin and C-peptide as well as rapid changes of melatonin levels permits conclusions that melatonin could to be involved in regulation of food intake. Study was supported by grant MZCR NR-9055-4.