In:
American Journal of Physiology-Endocrinology and Metabolism, American Physiological Society, Vol. 283, No. 4 ( 2002-10-01), p. E702-E710
Kurzfassung:
Arginine stimulates growth hormone (GH) secretion, possibly by inhibiting hypothalamic somatostatin (SS) release. Insulin-like growth factor I (IGF-I) inhibits GH secretion via effects at the pituitary and/or hypothalamus. We hypothesized that if the dominant action of IGF-I is to suppress GH release at the level of the pituitary, then the arginine-induced net increase in GH concentration would be unaffected by an IGF-I infusion. Eight healthy young adults (3 women, 5 men) were studied on day 2 of a 47-h fast for 12 h (35th-47th h) on four occasions. Saline (Sal) or 10 μg · kg −1 · h −1 recombinant human IGF-I was infused intravenously for 5 h from 37 to 42 h of the 47-h fast. Arginine (Arg) (30 g iv) or Sal was infused over 30 min during the IGF-I or Sal infusion from 40 to 40.5 h of the fast. Subjects received the following combinations of treatments in random order: 1) Sal + Sal; 2) Sal + Arg; 3) IGF-I + Sal; 4) IGF-I + Arg. Peak GH concentration on the IGF-I + Arg day was ∼45% of that on the Sal + Arg day. The effect of arginine on net GH release was calculated as [(Sal + Arg) − (Sal + Sal)] − [(IGF-I + Arg) − (IGF-I + Sal)] . There was no significant effect of IGF-I on net arginine-induced GH release over control conditions. These findings suggest that the negative feedback effect of IGF-I on GH secretion is primarily mediated at the pituitary level and/or at the hypothalamus through a mechanism different from the stimulatory effect of arginine.
Materialart:
Online-Ressource
ISSN:
0193-1849
,
1522-1555
DOI:
10.1152/ajpendo.00075.2002
Sprache:
Englisch
Verlag:
American Physiological Society
Publikationsdatum:
2002
ZDB Id:
1477331-4
SSG:
12
