Ghrelin - growth hormone releasing and orexigenic hormone in men declines with age, insulin and with decrease in testosterone concentration.

OBJECTIVES: Ghrelin, a natural ligand of the growth-hormone secretagouges receptor is the peptide known because of its growth hormone (GH)-releasing as well as orexigenic actions. THE AIM of the study was to examine the relationship between ghrelin levels and age, weight, glucose metabolism markers, GH, IGF-1 and androgens in men.

PATIENTS AND METHODS: The study included 19 healthy men aged 16-73 yrs, mean 46,8 +/-18,5 (mean +/- SD). The height, weight, and body mass index (BMI) of the study subjects were assessed and serum concentration of fasting ghrelin, leptin, GH, IGF-1, glucose, insulin, estradiol, testosterone and DHA-S were measured.

RESULTS: The negative correlation between age and serum ghrelin levels (r=-0,52; p<0,04) in men was found. In men under 30 years old serum ghrelin levels were significantly higher compared to men over 60 years old (p<0,02). Serum ghrelin levels in men were significantly lower compared to healthy women aged 43,5 +/- 12 years old (p<0,008). Serum insulin levels correlated negatively with ghrelin levels (r= -0,87; p<0,0006) and serum testosterone concentrations correlated with ghrelin levels (r= 0,69; p<0,00006).

CONCLUSION: Our findings demonstrate that the serum ghrelin levels in men decline with age, is lower than in women and correlate negatively with fasting insulin levels. We demonstrated, for the first time, that serum testosterone levels in men correlate with total ghrelin levels.