leptin and Turner-Syndrome

The fundamental aspects of the hypothalamic luteinizing hormone-releasing hormone (LHRH)(1) [1]pulse generator-pituitary gonadotrophin-gonadal apparatus in mammals have striking commonalities. There are, however, critical, substantive differences in the neuroendocrinology of puberty among species. The onset of puberty in the human is marked by an increase in the amplitude of LH pulses, an indirect indicator of the increase in amplitude of LHRH pulses. The hypothalamic LHRH-pituitary gonadotrophin complex is functional by at least 0.3 gestation in the human foetus; the sex difference in the fetal and neonatal pattern of LH and FSH secretion is an apparent consequence of imprinting of the fetal hypothalamus-pituitary-gonadotropin apparatus by fetal testosterone. Until about 6 months of age in boys and 12-24 months in girls, the testes and ovaries respond to the increased LH in boys and follicle-stimulating hormone (FSH) in girls by secreting testosterone and oestradiol, respectively, reaching levels that are not again achieved before the onset of puberty. Striking features of the ontogeny of the human hypothalamic pulse generator are: (1) its development and function in the foetus; (2) the continued function of the hypothalamic LHRH pulse generator-pituitary gonadotrophin-gonadal axis in infancy; (3) the gradual damping of hypothalamic LHRH oscillator activity during late infancy; (4) its quiescence during childhood - the so-called juvenile pause; (5) during late childhood the gradual disinhibition and reactivation of the LHRH pulse generator, mainly at night; (6) the increasing amplitude of the LHRH pulses, which are reflected in the progressively increased and changing pattern of circulating LH pulses, with the approach of and during puberty. The intrinsic central nervous system (CNS) mechanisms responsible for the inhibition of the LHRH pulse generator during childhood (the juvenile phase) involve the major role of an inhibitory neuronal system - the CNS inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and GABAergic neurons, as revealed by studies in the rhesus monkey by Terasawa and her associates. With the onset of puberty, the disinhibition and reactivation of the LHRH pulse generator is associated with a fall in GABAergic neurotransmission and a concomitant increase in the input of excitatory amino acid neurotransmitters (including glutamate) and possibly astroglial-derived growth factors. Despite remarkable progress over the past three dec

Topics: Animals; Follicle Stimulating Hormone; Gonadotropin-Releasing Hormone; Gonads; Humans; Hypothalamo-Hypophyseal System; Leptin; Luteinizing Hormone; Male; Neurosecretory Systems; Neurotransmitter Agents; Pituitary-Adrenal System; Progesterone; Puberty; Puberty, Precocious; Testosterone; Turner Syndrome

Concomitant evaluation of the metabolic and growth-promoting effects of growth hormone (GH) therapy in Turner syndrome (TS) may be used in the prediction of the growth response to GH therapy.. To evaluate the metabolic effects of GH therapy in TS and correlation with the short-term growth response.. 24 prepubertal children with TS, aged 9.4 +/- 2.6 years were followed for auxology and IGF-I, IGFBP-3, leptin, ghrelin, adiponectin, lipids and OGTT results in a prospective multicenter study.. GH (Genotropin) in a dose of 50 microg/kg/day for 1 year.. Height standard deviation score (SDS) increased from -3.9 +/- 1.5 to -3.5 +/- 1.4 (p = 0.000) on therapy. BMI did not change. IGF-I SDS increased from -2.3 +/- 0.4 to -1.6 +/- 1.1 at 3 and 6 months (p = 0.001) and decreased thereafter. Serum leptin decreased significantly from 2.3 +/- 3.9 to 1.7 +/- 5.3 ng/ml (p = 0.022) at 3 months and increased afterwards. Serum ghrelin decreased from 1.2 +/- 0.8 to 0.9 +/- 0.4 ng/ml (p = 0.005) with no change in adiponectin. Basal and stimulated insulin levels also increased significantly. Delta height SDS over 1 year showed a significant correlation with Delta IGF-I(0-3 months) (r = 0.450, p = 0.027).. IGF-I may be considered as a marker of growth response in TS at short term. Leptin shows a decrease at short term but does not have a correlation with growth response. The decrease in ghrelin in face of unchanged weight seems to be associated with increase in IGF-I and insulin levels. The unchanged adiponectin levels in spite of an increase in insulin levels indicates that adiponectin is mainly affected by weight, not insulin.

Topics: Adiponectin; Child; Child, Preschool; Cholesterol; Female; Ghrelin; Growth; Human Growth Hormone; Humans; Insulin Resistance; Leptin; Peptide Hormones; Triglycerides; Turner Syndrome

Women with Turner syndrome (TS) have increased risks of atherosclerosis, diabetes mellitus, and obesity. We hypothesized that women with TS have adverse metabolic or inflammatory markers for cardiovascular disease compared with normal women and estrogen-deficient controls. This was a cross-sectional study conducted at University College London Hospitals, UK. One hundred seventeen estrogen-treated women with TS and normal fasting blood glucose were compared with 30 age-matched normal controls and 31 estrogen-treated women with 46,XX premature ovarian failure (POF). The main outcome measures were markers of the metabolic syndrome, including the adipokines IL-6 and leptin, and C-reactive protein (CRP). TS women were more obese than controls (waist circumference, 79.9 +/- 12.4, 73.5 +/- 6.9, and 74.7 +/- 8.6 cm in TS, normal subjects, and POF controls, respectively; P = 0.005; body mass index, 26.8 +/- 5.8, 23.7 +/- 3.2, and 22.9 +/- 3.4 kg/m2; P < 0.001). This obesity was associated with increased CRP (2.9 +/- 1.5, 0.8 +/- 1.0, and 1.2 +/- 0.9 mg/liter; P < 0.001) and IL-6 concentrations (1.5 +/- 0.7, 1.0 +/- 1.5, and 1.2 +/- 0.5 pg/ml; P = 0.014), but lower fasting serum insulin (4.7 +/- 2.3, 6.3 +/- 3.0, and 6.9 +/- 2.9 mIU/ml; P = 0.004), glucose (83 +/- 11, 90 +/- 7, and 90 +/- 7 mg/dl; P < 0.001), and leptin (10.2 +/- 6.3, 14.4 +/- 7.6, and 14.8 +/- 8.1 ng/ml; P = 0.048). Triglyceride concentrations were similar in TS and POF women and were greater than in normal controls (97 +/- 53, 97 +/- 53, and 71 +/- 27 mg/dl; P = 0.024). We conclude that women with TS have various physical and biochemical features suggestive of the metabolic/insulin resistance syndrome, but there is a discrepancy among CRP, IL-6, and leptin, with leptin and fasting insulin concentrations being lower than expected for the degree of obesity. Obesity and estrogen therapy do not fully explain these findings. Women with TS may have specific metabolic defects contributing to cardiovascular risk.

Topics: Adipose Tissue; Adult; C-Reactive Protein; Female; Humans; Interleukin-6; Leptin; Obesity; Primary Ovarian Insufficiency; Turner Syndrome

Serum IGF-I levels are monitored during GH replacement treatment in adults with GH deficiency (GHD) to guide GH dose adjustment and to minimize occurrence of GH-related side-effects. This is not routine practice in children treated with GH. The aim of this study was to evaluate changes in (1) serum IGF-I, IGFBP-3 and IGF-I/IGFBP-3 molar ratio, and (2) serum leptin, an indirect marker of GH response, during the first year of GH treatment in children with disordered growth.. An observational prospective longitudinal study with serial measurements at five time points during the first year of GH treatment was carried out. Each patient served as his/her own control.. The study included 31 patients, grouped as (1) GHD (n = 20) and (2) non-GHD (Turner syndrome n = 7; Noonan syndrome n = 4), who had not previously received GH treatment.. Serum IGF-I, IGFBP-3 and leptin levels were measured before treatment and after 6 weeks, 3 months, 6 months and 12 months of GH treatment, with a mean dose of 0.5 IU/kg/wk in GHD and 0.7 IU/kg/wk in non-GHD groups. IGF-I, IGFBP-3 and the calculated IGF-I/IGFBP-3 molar ratio were expressed as SD scores using reference values from the local population.. In the GHD group, IGF-I SDS before treatment was lower compared with the non-GHD (-5.4+/-2.5 vs. -1.8+/-1.0; P<0.001). IGF-I (-1.8 SDS +/- 2.2) and IGFBP-3 (-1.1 SDS +/- 0.6) levels and their molar ratios were highest at 6 weeks and remained relatively constant thereafter. In the non-GHD group, IGF-I levels increased throughout the year and were maximum at 12 months (0.3 SDS +/- 1.4) while IGFBP-3 (1.1 SDS +/- 0.9) and IGF-I/IGFBP-3 molar ratio peaked at 6 months. In both groups, IGF-I SDS and IGF-I/IGFBP-3 during treatment correlated with the dose of GH expressed as IU/m2/week (r-values 0. 77 to 0.89; P = 0.005) but not as IU/kg/week. Serum leptin levels decreased significantly during GH treatment in the GHD (median before treatment 4.0 microg/l; median after 12 months treatment 2.4 microg/l; P = 0.02) but not the non-GHD (median before treatment 3.0 microg/l; median after 12 months treatment 2.6 microg/l). In the GHD group, serum leptin before treatment correlated with 12 month change in height SDS (r = 0.70, P = 0.02).. The pattern of IGF-I, IGFBP-3 and their molar ratio during the first year of GH treatment differed between the GHD and non-GHD groups. Calculation of GH dose by surface area may be preferable to calculating by body weight. As a GH dose-dependent increase in serum IGF-I and IGF-I/IGFBP-3 may be associated with adverse effects, serum IGF-I and IGFBP-3 should be monitored routinely during long-term GH treatment. Serum leptin was the only variable that correlated with first year growth response in GHD.

Topics: Adolescent; Child; Child, Preschool; Dose-Response Relationship, Drug; Female; Growth Disorders; Growth Hormone; Human Growth Hormone; Humans; Infant; Insulin-Like Growth Factor Binding Protein 3; Insulin-Like Growth Factor I; Leptin; Male; Noonan Syndrome; Prospective Studies; Turner Syndrome

The influence of exogenous insulin and estrogen substitution on serum leptin-like immunoreactivity was studied longitudinally in patients with type-I diabetes and Turner syndrome using a specific radioimmunoassay. Prepubertal, pubertal and postpubertal samples of 17 patients (9 girls, 8 boys) with type-I diabetes mellitus developing obesity were compared to those of 17 normal-weight controls matched for gender, age and diabetes duration. Six obese and six normal-weight girls with Turner syndrome were studied without hormone substitution, with ethinylestradiol alone, and with cyclic estradiol/gestagen substitution. The mean leptin levels of the girls with diabetes were two times higher than boys at all times, while insulin doses and glycemic control had no influence. In Turner syndrome estrogen substitution led to increased leptin levels only in the obese group. This study revealed that both body weight above normal and female sex steroids seem to be necessary to elevate leptin concentrations, while exogenous insulin has no effect.

Topics: Adolescent; Child; Diabetes Mellitus, Type 1; Estrogens; Female; Humans; Insulin; Leptin; Longitudinal Studies; Male; Obesity; Sex Factors; Turner Syndrome