Effect of insulin, glucagon or dexamethasone on the production of insulin-like growth factor I in cultured rat hepatocytes.
We studied the effect of insulin, glucagon or dexamethasone on the production of insulin-like growth factor I (IGF-I) by cultured rat hepatocytes. Hepatocytes were isolated from normal adult rat livers and cultured in MEM, as nearly confluent monolayers. In the absence of such hormones, IGF-I and albumin accumulated in the culture medium almost linearly for periods up to 24 hours with the accumulation rates of 140 mU/mg cell protein per hour and 1.2 micrograms/mg cell protein per hour, respectively. Cycloheximide (5 micrograms/ml) almost completely inhibited the accumulation of IGF-I and albumin in the medium. Insulin at concentrations over 10(-10) M significantly inhibited the production of IGF-I in spite of the increased production of albumin. Conversely, glucagon stimulated the production of IGF-I at concentrations over 10(-8) M, but inhibited the production of albumin at concentrations over 10(-10) M. Dexamethasone stimulated the production of IGF-I at concentrations over 10(-7) M, but had no significant effects on the production of albumin. Thus, IGF-I production of hepatocytes is regulated by several hormones with different manner from albumin production.
Masumoto
A
A
Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka.
Natori
S
S
Iwamoto
H
H
Uchida
E
E
Ohashi
M
M
Sakamoto
S
S
Nawata
H
H
D000818:Animals; D003864:Depression, Chemical; D003907:Dexamethasone / Q000494:pharmacology*; D005934:Glucagon / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical
D007328:Insulin; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone; D005934:Glucagon