Elevated plasma levels of alpha-melanocyte stimulating hormone (alpha-MSH)are correlated with insulin resistance in obese men

OBJECTIVE: The role of alpha-melanocyte stimulating hormone (MSH) in obesit y has been well-documented. However, circulating alpha-MSH concentrations i n obese men and their relationship with clinical indicators of obesity and glucose metabolism have not as yet been evaluated. METHODS: We measured the plasma concentrations of alpha-MSH in 15 obese and 15 non-obese male subjects. The relationship of the plasma concentrations of alpha-MSH with body mass index (BMI), body fat mass (measured by bioelec tric impedance), body fat distribution (measured by computed tomography), i nsulin levels, insulin resistance (assessed by the glucose infusion rate (G IR) during an euglycemic hyperinsulinemic clamp study) and with the serum c oncentrations of leptin and TNF-alpha were also evaluated. RESULTS: In obese men, the plasma alpha-MSH concentrations were significant ly increased compared with those in nonobese men (P < 0.02). The plasma lev els of alpha-MSH were positively correlated with BMI (r = 0.560, P < 0.05). fasting insulin levels (r = 0.528, P < 0.05) and with visceral fat area (r = 0.716, P < 0.01), but negatively correlated with GIR (r = -0.625, P < 0. 02) in obese male subjects. There were significant correlations between pla sma concentrations of alpha-MSH and visceral fat area (r = 0.631, P < 0.02) , and GIR (r = -0.549, Pc: 0.05) in non-obese male subjects. Circulating co ncentrations of alpha-MSH were not significantly correlated with the serum concentrations of leptin and TNF-alpha in both obese and non-obese men. CONCLUSION: Circulating concentrations of alpha-MSH are significantly incre ased and correlated with insulin resistance in obese men.