title: 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.
abstract: 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.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Sjögren
authors.forename: J L
authors.initials: JL
authors.lastname: Liu
authors.forename: K
authors.initials: K
authors.lastname: Blad
authors.forename: S
authors.initials: S
authors.lastname: Skrtic
authors.forename: O
authors.initials: O
authors.lastname: Vidal
authors.forename: V
authors.initials: V
authors.lastname: Wallenius
authors.forename: D
authors.initials: D
authors.lastname: LeRoith
authors.forename: J
authors.initials: J
authors.lastname: Törnell
authors.forename: O G
authors.initials: OG
authors.lastname: Isaksson
authors.forename: J O
authors.initials: JO
authors.lastname: Jansson
authors.forename: C
authors.initials: C
authors.lastname: Ohlsson
mesh_terms: 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
chemical_list: D007334:Insulin-Like Growth Factor I