TY - JOUR
T1 - Endocrine responses to acute and chronic high-altitude exposure (4,300 meters)
T2 - Modulating effects of caloric restriction
AU - Barnholt, Kimberly E.
AU - Hoffman, Andrew R.
AU - Rock, Paul B.
AU - Muza, Stephen R.
AU - Fulco, Charles S.
AU - Braun, Barry
AU - Holloway, Leah
AU - Mazzeo, Robert S.
AU - Cymerman, Allen
AU - Friedlander, Anne L.
PY - 2006
Y1 - 2006
N2 - High-altitude anorexia leads to a hormonal response pattern modulated by both hypoxia and caloric restriction (CR). The purpose of this study was to compare altitude-induced neuroendocrine changes with or without energy imbalance and to explore how energy sufficiency alters the endocrine acclimatization process. Twenty-six normal-weight, young men were studied for 3 wk. One group [hypocaloric group (HYPO), n = 9] stayed at sea level and consumed 40% fewer calories than required to maintain body weight. Two other groups were deployed to 4,300 meters (Pikes Peak, CO), where one group (ADQ, n = 7) was adequately fed to maintain body weight and the other [deficient group (DEF), n = 10] had calories restricted as above. HYPO experienced a typical CR-induced reduction in many hormones such as insulin, testosterone, and leptin. At altitude, fasting glucose, insulin, and epinephrine exhibited a muted rise in DEF compared with ADQ. Free thyroxine, thyroid-stimulating hormone, and norepinephrine showed similar patterns between the two altitude groups. Morning cortisol initially rose higher in DEF than ADQ at 4,300 meters, but the difference disappeared by day 5. Testosterone increased in both altitude groups acutely but declined over time in DEF only. Adiponectin and leptin did not change significantly from sea level baseline values in either altitude group regardless of energy intake. These data suggest that hypoxia tends to increase blood hormone concentrations, but anorexia suppresses elements of the endocrine response. Such suppression results in the preservation of energy stores but may sacrifice the facilitation of oxygen delivery and the use of oxygen-efficient fuels.
AB - High-altitude anorexia leads to a hormonal response pattern modulated by both hypoxia and caloric restriction (CR). The purpose of this study was to compare altitude-induced neuroendocrine changes with or without energy imbalance and to explore how energy sufficiency alters the endocrine acclimatization process. Twenty-six normal-weight, young men were studied for 3 wk. One group [hypocaloric group (HYPO), n = 9] stayed at sea level and consumed 40% fewer calories than required to maintain body weight. Two other groups were deployed to 4,300 meters (Pikes Peak, CO), where one group (ADQ, n = 7) was adequately fed to maintain body weight and the other [deficient group (DEF), n = 10] had calories restricted as above. HYPO experienced a typical CR-induced reduction in many hormones such as insulin, testosterone, and leptin. At altitude, fasting glucose, insulin, and epinephrine exhibited a muted rise in DEF compared with ADQ. Free thyroxine, thyroid-stimulating hormone, and norepinephrine showed similar patterns between the two altitude groups. Morning cortisol initially rose higher in DEF than ADQ at 4,300 meters, but the difference disappeared by day 5. Testosterone increased in both altitude groups acutely but declined over time in DEF only. Adiponectin and leptin did not change significantly from sea level baseline values in either altitude group regardless of energy intake. These data suggest that hypoxia tends to increase blood hormone concentrations, but anorexia suppresses elements of the endocrine response. Such suppression results in the preservation of energy stores but may sacrifice the facilitation of oxygen delivery and the use of oxygen-efficient fuels.
KW - Acclimatization
KW - Altitude
KW - Caloric restriction
KW - Energy balance
KW - Hormones
KW - Hypoxia
UR - http://www.scopus.com/inward/record.url?scp=33744936792&partnerID=8YFLogxK
U2 - 10.1152/ajpendo.00449.2005
DO - 10.1152/ajpendo.00449.2005
M3 - Article
C2 - 16380390
AN - SCOPUS:33744936792
SN - 0193-1849
VL - 290
SP - E1078-E1088
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 6
ER -