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Key words: DELAYED PUBERTY, GIRLS, NPY, IGF-I, CORTISOL
ABSTRACT
Constitutional delay of puberty (CDP) in otherwise Healtliy girls is defined as failure to develop secondary sexual features past the age of 13 years (two standard deviations above the mean age at which secondary sexual features appear in the population of girls). The inhibitory action of neuropeptide Y (NPY) on the gonaclotropic and somatotropic systems in experimental animals and stimulation by NPY of the hypotlialamic-pitnitary-adrenal axis have been reported, prompting us to study the levels of NPY, insulin-like growth factor-I (IGP-I) and cortisol in eight girls unth CDP and normal weight (body mass index (BMI) 21.7 ± 4.5 kg/m^sup 2^). The results were compared until those from a group of 40 girls (BMI = 20.0 ± 3.1 kg/m^sup 2^) who demonstrated a normal course of puberty (NP). All girls were studied at menarche (mean age at menarche, study vs. control: 16.4 ± 0.7 vs. 12.6 ± 0.9 years). To measure NPY and ICF-1 we used a radioimmunoassay method, whereas cortisol was measured with an enzyme immunoassay. Blood was collected between 08.00 and 09.00 following an overnight fast. NPY was higher in girls with CDP (181.6 ± 106.4 pg/ml) than in girls with NP (55.5 ± 26.3 pg/ml; p < 0.001). In the former group, cortisol was higher (397.3 ± 241.6 nmol/l) than in NP girls (142.7 ± 98.0 nmol/l; p < 0.01). Levels of ICF-I in CDP girls were lower than in NP girls (558.0 ± 122.6 vs. 756.5 ± 226.8 ng/ml; p < 0.01). The results corroborate the involvement of NPY in sexual maturation and its role in delayed puberty.
INTRODUCTION
Constitutional delay of puberty (CDP) is a condition affecting otherwise healthy girls. CDP is defined as failure to develop secondary sexual features (breast growth) past the age of 13 years, representing two standard deviations above the mean age at which secondary sexual features appear in a given population of girls . Familial aggregation of CDP among parents and children has frequently been reported, substantiating the role of inheritance in the regulation of puberty2.
The onset of puberty is a concerted sequence of events involving many co-acting neuropeptides, neurotransmitters and neurosteroids . Among important mediators of metabolic and endocrine processes is neuropeptide Y...