Here we analyzed associations between muscles mass, total bone mineral content (BMC), lumbar spine bone density (BMD L1-L4) and serum or urine hormones in healthy peripubertal girls. Total BMC and areal BMD L1-L4, muscle mass and fat were measured by dual-energy X-ray absorptiometry (DXA). Muscle force (N) was estimated by a dynamometer. Circulating estradiol, folliclestimulating hormone (FSH), luteinizing hormone (LH), 25-hydroxy vitamin D, parathyroid hormone (PTH), insulin-like growth factor 1 (IGF-1), leptin, osteocalcin, bone isoenzyme of alkaline phosphatase (bALP) and total calcium and phosphorus were quantified as the nocturnal melatonin and serotonin urinary excretion. Partial correlations adjusted for height, Tanner score and physical activity confirmed positive relationships between BMC or BMD L1-L4 (Z-score) and lean mass or fat. Furthermore, positive relationship was observed between BMC or BMD L1-L4 (Z-score) and serum leptin. After adjustment for Tanner score and physical activity, positive associations were observed between lean mass and IGF-1, leptin levels or muscle force. We proved positive relationships between bone mass and serum leptin in peripubertal girls., V. Cirmanova, I. Zofkova, P. Kasalicky, V. Lanska, M. Bayer, L. Starka, R. Kanceva., and Obsahuje bibliografii
Inhibin B is a gonadal dimeric polypeptide hormone that regulates synthesis and secretion of follicle stimulating hormone (FSH) in a negative feedback loop. The aim of the present study was to determine changes in serum inhibin B, gonadotropins and testosterone concentrations during childhood and puberty in males. We studied the relationship between circulating inhibin B, gonadotropins and testosterone in serum of healthy boys during the first two years of life and then in pubertal development. Using a recently developed two-side enzyme-linked immunosorbent assay (ELISA), inhibin B levels were measured in the serum of 78 healthy boys divided into eleven age groups from birth to the end of pubertal development. In addition, serum levels of gonadotropins and testosterone were measured. Serum inhibin B, gonadotropins and testosterone increased during the first months of postnatal life. A peak in serum inhibin B and gonadotropins concentrations was observed around 3-4 months of age. There was a significant positive correlation between serum inhibin B and gonadotropins and testosterone levels during the first 2 years of life. After this early increase, serum inhibin B, gonadotropins and testosterone levels decreased significantly and remained low until puberty followed by an increase beginning with the onset of puberty. Serum levels of inhibin B reached a peak at stage G3 of puberty. Around midpuberty, inhibin B lost its positive correlation with luteinizing hormone (LH) and testosterone from early puberty, and developed a strong negative correlation with FSH, which persisted into adulthood. We conclude that inhibin B plays a key role in the regulation of the hypothalamic-pituitary-gonadal hormonal axis during male childhood and pubertal development. Inhibin B is a direct marker of the presence and function of Sertoli cells and appears to reflect testicular function in boys., M. Chada, R. Průša, J. Bronský, K. Kotaška, K. Šídlová, M. Pechová, L. Lisá., and Obsahuje bibliografii
a1_Inhibin B, produced by granulosa cells in the ovary, is a heterodimeric glycoprotein suppressing synthesis and secretion of the follicle stimulating hormone (FSH). The aim of the present study was to determine hormone profiles of inhibin B, FSH, luteinizing hormone (LH), and estradiol in girls during childhood and puberty and to evaluate whether inhibin B is a marker of follicle development. We examined the correlation between inhibin B and gonadotropins and estradiol during the first two years and across the pubertal development. Using a specific two-side enzyme-linked immunosorbent assay (ELISA), inhibin B levels were measured in the serum of 53 healthy girls divided into 8 groups according to age. In addition, serum FSH, LH, and estradiol were measured by chemiluminescent immunoassay in all serum samples. A rise in serum levels of inhibin B (55.2±7.3 ng/l, mean ± S.E.M.) and FSH (1.78±0.26 UI/l), concomitant with a moderate increment of serum LH (0.36±0.09 UI/l) and estradiol (45.8±12.2 pmol/l) concentrations was observed during the first three months of life and declined to prepubertal concentrations thereafter. A strong positive correlation between inhibin B and FSH (r = 0.48, p<0.05), LH (r = 0.68, p<0.001) and estradiol (r = 0.59, p<0.01) was demonstrated during the first 2 years of life. A rise in serum levels of inhibin B, FSH, LH, and estradiol was found throughout puberty. Inhibin B had a strong positive correlation with FSH (stage I of puberty: r = 0.64, p<0.05; stage II of puberty: r = 0.86, p<0.01), LH (I: r = 0.61, p<0.05; II: r = 0.67, p<0.05), and estradiol (II: r = 0.62, p<0.05) in early puberty. From pubertal stage II, inhibin B lost this relationship to gonadotropins and estradiol. Serum inhibin B and FSH levels increased significantly during pubertal development, with the highest peak found in stage III of puberty (133.5±14.3 ng/l), and decreased thereafter., a2_In conclusion, inhibin B is produced in a specific pattern in response to gonadotropin stimulation and plays an important role in the regulation of the hypothalamic-pituitary-gonadal axis during childhood and puberty in girls. Inhibin B is involved in regulatory functions in developing follicles and seems to be a sensitive marker of ovarian follicle development., M. Chada, R. Průša, J. Bronský, M. Pechová, L. Lisá., and Obsahuje bibliografii
This review focuses on current knowledge of leptin biology and the role of leptin in various physiological and pathophysiological states. Leptin is involved in the regulation of body weight. Serum leptin can probably be considered as one of the best biological markers reflecting total body fat in both animals and humans. Obesity in man is accompanied by increased circulating leptin concentrations. Gender differences clearly exist. Leptin is not only correlated to a series of endocrine parameters such as insulin, glucocorticoids, thyroid hormones, testosterone, but it also seems to be involved in mediating some endocrine mechanisms (onset of puberty, insulin secretion) and diseases (obesity, polycystic ovary syndrome). It has also been suggested that leptin can act as a growth factor in the fetus and the neonate., R. Janečková., and Obsahuje bibliografii