Comparison of oxytocin, leptin, vaspin and melatonin levels in hypopituitary, obese and healthy individuals

In hypopituitary (HP) patients, the incidence of obesity, insulin resistance and dyslipidemia increased. However, the exact cause of these increased metabolic problems is unclear. In this study, we examined the clinical and metabolic relationship between serum oxytocin, leptin, vaspin and melatonin levels and hypopituitarism based on the pathogenesis of obesity. At the same time, we aimed to elucidate the effects of central diabetes insipidus (CDI) on obesity, insulin resistance and dyslipidemia in HP patients. The study included 120 participants between 18-75 years of age, including 30 hypopituitary patients without central diabetes insipidus (HP CDI), 30 hypopiutary patients with central diabetes insipidus (HP+CDI), 30 obese patients, and 30 healthy volunteers. After an overnight fast, venous blood samples were collected in the morning for fasting blood glucose, insulin, low density lipoprotein, high density lipoprotein, triglyceride, total cholesterol and oxytocin levels. Body mass index was calculated and bioelectrical impedance analysis was used to determine body composition. As a result, regardless of the presence of CDI, higher body mass index and body fat ratios were detected in HP patients than in the control group (p<0.05). More insulin resistance was found in HP+CDI patients compared to HP-CDI patients and the control group (p<0.05). Serum oxytocin level was found to be lower in HP patients than in the obese and control groups (p<0.05). Serum leptin level was found to be high in obese patients (p<0.05); no significant difference was found in other groups. Serum vaspin level was the lowest in obese patients (p<0.05), while it was significantly lower in HP patients than in the control group (p<0.05). Serum melatonin levels were significantly lower in the HP+CDI group and in the obese group compared to the control group (p<0.05), but no significant difference was found between these two groups. In the HP+CDI group, a significant negative correlation was found between serum oxytocin, leptin, vaspin and melatonin levels and insulin resistance and alanine aminotransferase value (p<0.05). In the HP-CDI group, a significant negative correlation was found between serum leptin and vaspin levels and xii body fat ratios (p<0.05), while no significant correlation was found between melatonin and oxytocin levels and anthropometric and metabolic parameters. According to logistic regression analysis, the presence of CDI is an independent variable that causes an increase in insulin resistance. We concluded that serum oxytocin and vaspin levels were low in HP patients and there was no change in serum leptin and melatonin levels. We found that serum oxytocin, leptin and vaspin levels did not change in CDI; serum melatonin levels were lower. In addition, CDI is a risk factor that increases insulin resistance. At the same time, the negative correlation between insulin resistance and serum melatonin in CDI suggests that insulin resistance may progress through melatonin.