Hyperendorphinemia in obses children and adolescents

To study the role of opioid peptides in human obesity, plasma β-endorphin (βEP), β-lipotropin (βLPH), and cortisol resting values, circadian rhythms, and responses to hypoglycemia were studied in 6 prepubertal and 6 pubertal obses adolescents (at least 40% above ideal body weight) and in 10 normal subjects matched for age, sex, adn pubertal development. Baseline plasma βLPH and βEP concentrations in both obese children and adolescents were twice as high as those in normal controls, while cortisol levels were not different. Cortisol, βEP, and JSLPH levels had a clear circadian rhythmicity in all subjects, with the exception of obese pubertal boys whose plasma βEP concentrations were constant throughout the day. After insulin administration, the fall in blood sugar was similar in all groups. Plasma cortisol and βEP responses were similar in both obese and normal prepubertal subjects. In obese pubertal adolescents, βEP did not increase significantly after hypoglycemia, although it did increase in normal weight pubertal subjects. In normal prepubertal subjects, the circadian rhythms of βEP and βLPH secretion and release induced by hypoglycemia suggest the presence of a well developed neuroendocrine control of proopiomelanocortin-relatedpeptide secretion. In prepubertal obese children, the increased plasma βEP and jSLPH levels with the maintenance of their circadian rhythm and responsivity to hypoglycemia suggest overactivity of anterior pituitary secretion. In obese adolescents, in spite of the normal rhythm of βLPH and cortisol, βEP levels did not change throughout the day, thus suggesting βEP secretion from nonpituitary sources in these subjects. The present study indicates a possible direct role for hyperendorphinemia in the induction of overeating in obese children and adolescents.