Association of the pituitary-testicular axis function and sex hormone-binding globulin with melatonin secretion in morbidly obese men

A possible relationship between melatonin (MEL) secretion and pituitary-testicular function as well as the circadian rhythmicity of serum MEL, lutropin (LH), folitropin (FSH), estradiol (E2), total testosterone (T) and sex hormone-binding globulin (SHBG) were evaluated in 16 men with the primary obesity (body mass index - BMI > 43 kg/m2; waist-to-hip circumference ratio - WHR > 1.0) and in 17 healthy volunteers with normal body weight. The mean 24-h MEL level was significantly higher in obese patients than in healthy control individuals. Moreover, all obese men showed some abnormalities of MEL circadian pattern such as decreased ratio between day and night MEL levels, abnormal secretory peaks during the light hours and lower interindividual variability for timing amplitude. Abnormal circadian variations of MEL were associated with reduced 24-h mean values of LH, FSH, T and SHBG, whereas E2 levels were elevated. (author). 49 refs, 4 figs, 2 tabs