Changes of peripheral α-melanocyte–stimulating hormone in childhood obesity

Relationships of blood circulating melanocortins to childhood obesity are not well established. We evaluated serum α-melanocyte–stimulating hormone (α-MSH) in lean children and different study groups of childhood obesity. We examined serum α-MSH in 52 otherwise healthy children with childhood obesity (Ob; mean age, 11 years; 32 girls/20 boys), 27 normal-weight children of same age, 7 additional obese patients with reduced melanocortin-4 receptor function (MC4Rmut), and 22 patients with craniopharyngioma (CP). Fasting serum α-MSH and leptin were measured by radioimmunoassay. Serum α-MSH was also evaluated 1 hour after 500-kcal liquid meal (CP and Ob) and at the end of 1-year lifestyle intervention in 24 Ob patients. The α-MSH levels were similar in obese vs lean children but significantly lower in CP (P< .001) and significantly higher (P < .05) in MC4Rmut patients compared with Ob. One hour after liquid meal, α-MSH increased in patients with Ob but not with CP. After 1 year, α-MSH levels increased significantly in the successful weight reduction Ob subgroup despite unchanged cortisol levels. The α-MSH changes correlated to weight status changes (r = 0.67, P = .0003) but not to changes of cortisol, insulin, or homeostasis model assessment of insulin resistance index. Persistently low α-MSH levels in CP patients are suspected to be due to pituitary or hypothalamic damage. High peripheral levels in MC4Rmut carriers indicate up-regulation of α-MSH. Changes of weight status are associated with changes of peripheral α-MSH.