Impact of prolonged low-grade physical training on the in vivo glucocorticoid sensitivity and on glucocorticoid receptor-alpha mRNA levels of obese adolescents.
OBJECTIVE
Healthy individuals present variable responses of the hypothalamic-pituitary-adrenal (HPA) axis induced by different patterns of physical training. The aim of this study was to evaluate whether prolonged low-grade physical training influences the HPA axis and also glucocorticoid receptor-alpha (GRalpha) mRNA levels in mononuclear cells of obese adolescents.


METHODS
We studied 19 patients with BMI above the 95th percentile (male:female ratio 7:12) aged from 9.5 to 15.5 years. Patients underwent a 12-week physical exercise program. Before and after exercise, in vivo glucocorticoid sensitivity was determined by employing a very-low-dose intravenous dexamethasone suppression test, and in vitro GRalpha mRNA levels were evaluated by quantitative real-time PCR.


RESULTS
After exercise there was a trend to reduce the in vivo glucocorticoid sensitivity (p = 0.071) and a significant increase in GRalpha mRNA levels (p = 0.025).


CONCLUSIONS
For this subset of obese adolescents, prolonged low-grade physical training tended to reduce glucocorticoid sensitivity. The discrepancy of cortisol response to dexamethasone and the GRalpha mRNA measurement suggest a post-receptor phenomenon or should be related to target tissue-specific differences in glucocorticoid sensitivity. Future studies should address the adaptive GRalpha mRNA during different exercise protocols, and also the correlation of pituitary sensitivity with glucocorticoid target tissue sensitivity.
Faria
Cláudia Dutra Costantin
CD
Pediatric Endocrinology Unit, Pediatric Department of the Irmandade da Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil. ceclau@terra.com.br
Castro
Roberta Borges
RB
Longui
Carlos Alberto
CA
Kochi
Cristiane
C
Barbosa
Vera Lúcia Perino
VL
Sousa E Silva
Tatiane
T
Rocha
Mylene Neves
MN
Melo
Murilo Rezende
MR
Monte
Osmar
O
D000293:Adolescent; D001786:Blood Glucose; D001823:Body Composition; D003907:Dexamethasone / Q000494:pharmacology; D015444:Exercise / Q000502:physiology; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D009765:Obesity / Q000235:genetics / Q000378:metabolism* / Q000628:therapy*; D018579:Patient Selection; D010809:Physical Fitness / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D001786:Blood Glucose; D007328:Insulin; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; C411470:glucocorticoid receptor alpha; D003907:Dexamethasone