Leptin and ghrelin levels in humans during physical inactivity induced by head-down bed rest.
BACKGROUND
The aim of this study was to investigate the consequences of 20 d of physical inactivity using head-down bed rest (HDBR) at -6 degrees on leptin, ghrelin, and counter-regulatory hormone responses.


METHODS
Eight male volunteers were subjected to HDBR for 20 d. Variables measured before, during, and after HDBR included plasma cortisol, insulin, glucose, leptin, ghrelin, thyroid stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3).


RESULTS
No changes in ghrelin and leptin concentrations were observed during HDBR. Glucose concentration decreased significantly on the 20th day of HDBR compared to the pre-value (day 0) of HDBR (87.6 +/- 2.0 vs. 93 +/- 1.6 mg x dl(-1)). Significant correlation was observed between glucose and leptin concentrations.


CONCLUSIONS
The results provide the first evidence that 20 d of HDBR is not associated with an alteration in ghrelin concentration. Leptin, insulin, and cortisol concentrations did not differ during 20 d of HDBR.
Kanikowska
Dominika
D
Department of Physiology, Aichi Medical University School of Medicine, Nagakute, Japan. dominika@aichi-med-u.ac.jp
Sato
Maki
M
Iwase
Satoshi
S
Nishimura
Naoki
N
Shimizu
Yuuki
Y
Inukai
Yoko
Y
Sugenoya
Junichi
J
D000222:Adaptation, Physiological; D000328:Adult; D000704:Analysis of Variance; D015992:Body Mass Index; D054439:Ghrelin / Q000097:blood*; D005947:Glucose; D018475:Head-Down Tilt / Q000009:adverse effects*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D020738:Leptin / Q000097:blood*; D008297:Male; D057185:Sedentary Behavior; D013223:Statistics as Topic; D011795:Surveys and Questionnaires; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D054439:Ghrelin; D007328:Insulin; D020738:Leptin; D014284:Triiodothyronine; D013972:Thyrotropin; D005947:Glucose; D013974:Thyroxine; D006854:Hydrocortisone