Liver-derived insulin-like growth factor I (IGF-I) is the principal source of IGF-I in blood but is not required for postnatal body growth in mice.
The body growth of animals is regulated by growth hormone and IGF-I. The classical theory of this regulation is that most IGF-I in the blood originates in the liver and that body growth is controlled by the concentration of IGF-I in the blood. We have abolished IGF-I production in the livers of mice by using the Cre/loxP recombination system. These mice demonstrated complete inactivation of the IGF-I gene in the hepatocytes. Although the liver accounts for less than 5% of body mass, the concentration of IGF-I in the serum was reduced by 75%. This finding confirms that the liver is the principal source of IGF-I in the blood. However, the reduction in serum IGF-I concentration had no discernible effect on postnatal body growth. We conclude that postnatal body growth is preserved despite complete absence of IGF-I production by the hepatocytes.
Sjögren
K
K
Department of Internal Medicine, Division of Endocrinology, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.
Liu
J L
JL
Blad
K
K
Skrtic
S
S
Vidal
O
O
Wallenius
V
V
LeRoith
D
D
Törnell
J
J
Isaksson
O G
OG
Jansson
J O
JO
Ohlsson
C
C
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001835:Body Weight; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis* / Q000172:deficiency / Q000235:genetics; D008099:Liver / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout
D007334:Insulin-Like Growth Factor I