Growth hormone and insulin-like growth factor I responses to moderate submaximal acute physical exercise in man: effects of octreotide, a somatostatin analogue, administration.
We evaluated growth hormone (GH) and insulin-like growth factor I (IGF-I) response to moderate submaximal acute short-term physical exercise under basal conditions and after the administration of octreotide, a somatostatin analogue (SA), in a double-blind, counter-balanced experimental protocol. Seven untrained male volunteers performed two identical exercise tests, each on a treadmill (2.5% slope) for 30 minutes (min) at 60% of VO2max. Before starting the exercise test all the subjects received a single administration of placebo or octreotide and vice versa at two different sessions. Plasma GH, IGF-I and lactate assays were evaluated before starting, during, at the end and in the recovery phase. In the placebo-treated group GH rose significantly both during exercise and recovery whereas no significant modifications in IGF-I levels were observed. SA administration inhibited the exercise-dependent GH secretion, which showed a small rise only during exercise and returned to basal levels during recovery. In the same group, IGF-I decreased significantly after exercise compared to basal values. The results suggest that 1) in our experimental conditions acute physical exercise at aerobic threshold does not modify IGF-I concentration 2) SA is able to inhibit the exercise-dependent GH secretion and to decrease post-exercise IGF-I concentration.
Di Luigi
L
L
Laboratory of Endocrinological Research, Superior Institute of Physical Education (I.S.E.F.) of Rome, Italy.
Conti
F G
FG
Casini
A
A
Guidetti
L
L
Zezze
G
G
Pigozzi
F
F
Spera
G
G
Fortunio
G
G
Romanelli
F
F
D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D004311:Double-Blind Method; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology; D006728:Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D019382:Human Growth Hormone / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000097:blood*; D006801:Humans; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000037:antagonists & inhibitors; D007773:Lactates / Q000097:blood; D008297:Male; D015282:Octreotide / Q000008:administration & dosage / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010919:Placebos
D006728:Hormones; D007773:Lactates; D010919:Placebos; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D015282:Octreotide