scholarly journals Resting Level of Insulin-Like Growth Factor-1 Is Not at Play in Cardiac Enlargement in Endurance-Trained Adolescents

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Louise Rundqvist ◽  
Jan Engvall ◽  
Peter Blomstrand ◽  
Emma Carlsson ◽  
Maria Faresjö
Keyword(s):  
Growth Factor ◽  
Peak Oxygen Uptake ◽  
Cardiopulmonary Exercise Test ◽  
Thyroid Stimulating Hormone ◽  
Insulin Like Growth Factor ◽  
Metabolic Hormones ◽  
Cardiac Adaptation ◽  
Echocardiographic Examination ◽  
Circulating Levels ◽  
Stimulating Hormone

Purpose. The study aimed to investigate resting levels of several selected growth and metabolic hormones in a group of 24 endurance-trained adolescents (aged 13–19 years) compared with 24 untrained age- and sex-matched controls, and to investigate if increased cardiac dimensions were related to these hormones at rest with emphasis on insulin-like growth factor-1 (IGF-1). Methods. The hormones (cortisol, IGF-1, IGF-2, follicle-stimulating hormone, growth hormone, luteinizing hormone, prolactin, and thyroid-stimulating hormone) were analysed with chemiluminescence microparticle immunoassay (CMIA) or multiplex fluorochrome (Luminex) technique. Cardiac dimensions were assessed by echocardiographic examination at rest. Peak oxygen uptake was obtained by a maximal cardiopulmonary exercise test on a treadmill. Results. Circulating levels of analysed hormones at rest did not differ between the groups. A correlation was found between increased cardiac dimensions and IGF-1 in the controls, but not in the active group. This correlation declined also among the controls when the cardiac parameters were indexed for body surface area. Conclusion. Increased cardiac dimensions in endurance-trained adolescents could not be related to resting levels of hormones associated with growth and metabolism, including IGF-1 and GH. In addition, the resting levels of these hormones seem not to be affected by intense regular endurance exercise in adolescents. These findings may contribute to the knowledge about cellular signaling that trigger growth as well as cardiac adaptation to endurance training in young athletes.

Neuroendocrine Effects of Toxic and Low Blood Lead Levels in Children

PEDIATRICS ◽  
1992 ◽  
Vol 90 (2) ◽  
pp. 186-189
Author(s):  
Carol A. Huseman ◽  
Madan M. Varma ◽  
Carol R. Angle
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Growth Factor ◽  
Blood Lead ◽  
Thyroid Stimulating Hormone ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
The Central Nervous System ◽  
Growth Factor I ◽  
Stimulating Hormone

From 3 million to 4 million children In America have lead poisoning. This environmental toxin affects 1 in every 6 children younger than 6 years of age in the United States. The marked effects of lead toxicity on the central nervous system are well known, ie, lowering IQ and impairing memory, reaction time, and the ability to concentrate. Children are at greatest risk for the central nervous system effects of lead because the central nervous system is at its peak in development during the first few years of life. The negative correlation of stature and blood lead level (bPb) found in the National Health and Nutrition Examination Survey directed the authors to evaluate the possible neuroendocrine effects of this toxin in children. Twelve children were studied during toxic(≥40 µg/dL) and low bPb (<40 µg/dL). Classic provocative stimuli, l-dopa (15 mg/kg by mouth) and insulin (0.1 U/kg given intravenously), were used to determine human growth hormone (hGH) responses during toxic bPb and after chelation therapy in six of the subjects. An additional four subjects were studied during low bPb. In two patients LGH levels were determined every 20 minutes for 24 hours during toxic bPb. Thyroid-stimulating hormone and prolactin responses to thyrotropin-releasing hormone were also determined. All children studied showed growth retardation during toxic bPb. Mean peak hGH responses to provocative stimuli were lower during toxic bPb, but the responses were all within normal limits. The mean 24-hour hGH values were low in the two patients (0.8 ± 0.2 [SE] ng/mL and 2.0 ± 0.8 ng/mL) studied compared with normal control patients (6.4 ± 0.3 ng/mL). Insulin-like growth factor I values showed an inverse correlation with toxic blood bPb, up to 40 µg/dL. Basal thyroid-stimulating hormone, prolactin, thyroxine, and triiodothyronine concentrations were not affected by bPb. In addition, thyrold-stimulating hormone and prolactin responses to thyrotropin-releasing hormone were not affected by toxic or low bPb. Cortisol responses to insulin-induced hypoglycemia were normal (P ≤ .05). These observations, taken together, confirm the inadequacy of acute hGH responses to secretagogue as a reliable indicator of hGH secretion and indicate that lead-induced short stature may be due to diminished hGH secretion, which in turn results in reduced insulin-like growth factor I secretion, or that Pb may also directly inhibit insulin-like growth factor I formation.

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