title: Secretory dynamics of leptin in adolescent girls with anorexia nervosa and healthy adolescents.
abstract: Leptin, an adipocytokine that suppresses appetite and may regulate neuroendocrine pathways, is low in undernourished states like anorexia nervosa (AN). Although leptin exhibits pulsatility, secretory characteristics have not been well described in adolescents and in AN, and the contribution of hypoleptinemia to increased growth hormone (GH) and cortisol in AN has not been explored. We hypothesized that hypoleptinemia in AN reflects decreased basal and pulsatile secretion and may predict increased GH and cortisol levels. Sampling for leptin, GH, cortisol, and ghrelin was performed every 30 min (from 2000 to 0800) in 23 AN and 21 controls 12-18 yr old, and data were analyzed using Cluster and deconvolution methods. Estradiol, thyroid hormones, and body composition were measured. AN girls had lower pulsatile and total leptin secretion than controls (P < 0.0001) subsequent to decreased burst mass (P < 0.0001) and basal secretion (P = 0.02). Nutritional markers predicted leptin characteristics. In a regression model including BMI, body fat, and ghrelin, leptin independently predicted GH burst interval and frequency. Valley leptin contributed to 56% of the variability in GH burst interval, and basal leptin and fasting ghrelin contributed to 42% of variability in burst frequency. Pulsatile leptin independently predicted urine free cortisol/creatinine (15% of variability). Valley leptin predicted cortisol half-life (22% of variability). Leptin predicted estradiol and thyroid hormone levels. In conclusion, hypoleptinemia in AN is subsequent to decreased basal and pulsatile secretion and nutritionally regulated. Leptin predicts GH and cortisol parameters and with ghrelin predicts GH burst frequency. Low leptin and high ghrelin may be dual stimuli for high GH concentrations in undernutrition.
authors.affiliation: Neuroendocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Madhusmita
authors.initials: M
authors.lastname: Misra
authors.forename: Karen K
authors.initials: KK
authors.lastname: Miller
authors.forename: Kelly
authors.initials: K
authors.lastname: Kuo
authors.forename: Kathryn
authors.initials: K
authors.lastname: Griffin
authors.forename: Victoria
authors.initials: V
authors.lastname: Stewart
authors.forename: Emily
authors.initials: E
authors.lastname: Hunter
authors.forename: David B
authors.initials: DB
authors.lastname: Herzog
authors.forename: Anne
authors.initials: A
authors.lastname: Klibanski
mesh_terms: D000293:Adolescent; D000856:Anorexia Nervosa / Q000378:metabolism*; D016000:Cluster Analysis; D004958:Estradiol / Q000097:blood / Q000378:metabolism; D005260:Female; D054439:Ghrelin; D019382:Human Growth Hormone / Q000097:blood / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism; D007333:Insulin Resistance; D020738:Leptin / Q000097:blood* / Q000378:metabolism*; D009752:Nutritional Status; D036361:Peptide Hormones / Q000097:blood / Q000378:metabolism; D011673:Pulsatile Flow; D012016:Reference Values
chemical_list: D054439:Ghrelin; D020738:Leptin; D036361:Peptide Hormones; D019382:Human Growth Hormone; D004958:Estradiol; D006854:Hydrocortisone