mRNA of insulin-like growth factor (IGF) quantification and presence of IGF binding proteins, and receptors for growth hormone, IGF-I and insulin, determined by reverse transcribed polymerase chain reaction, in the liver of growing and mature male cattle.
Plasma insulin-like growth factor-I (IGF-I) concentrations were related to hepatic levels of IGF-I mRNA measured by competitive reverse transcription polymerase chain reaction (PCR) (RT-PCR) in neonatal (8 d old) calves, veal calves, fattened castrated bulls and mature intact bulls. Furthermore, the presence of mRNAs of IGF-II and of receptors for IGF-I (IGF-IR), growth hormone (GHR) and insulin (IR), as well as mRNAs of IGF binding proteins (IGFBP-1, -2 and -3) were assessed by RT-PCR. Hepatic IGF-I mRNA levels and plasma IGF-I concentrations in veal calves, fattened castrated bulls and in intact bulls were 4 to 8 times higher than in 8-d old calves and were 2 to 3 times higher in calves fed colostrum than in calves fed only milk replacer. Hepatic IGF-I mRNA concentrations were closely correlated (r = 0.92) with plasma IGF-I concentrations, suggesting that hepatic IGF-I production largely determines plasma IGF-I levels. The presence of IGF II, IGF-IR, GHR, IR and IGFBP-1, -2 and -3 mRNA was confirmed in the liver of 8-d old calves and older cattle as well, and among newborn calves their presence was independent of differences in nutrition. In conclusion, the major hepatic components of the GH-IGF axis were present in neonatal calves, but the IGF-I expression and therefore also plasma IGF-I levels were relatively low.
Cordano
P
P
Divison of Nutritional Pathology, Faculty of Veterinary Medicine, University of Berne, 3012, Berne, Switzerland.
Hammon
H M
HM
Morel
C
C
Zurbriggen
A
A
Blum
J W
JW
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002417:Cattle / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003126:Colostrum / Q000502:physiology; D004247:DNA / Q000737:chemistry; D017931:DNA Primers / Q000737:chemistry; D004587:Electrophoresis, Agar Gel / Q000662:veterinary; D005260:Female; D018969:Insulin-Like Growth Factor Binding Proteins / Q000032:analysis / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000032:analysis / Q000235:genetics; D008099:Liver / Q000737:chemistry / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D011247:Pregnancy; D012333:RNA, Messenger / Q000032:analysis / Q000737:chemistry; D011863:Radioimmunoassay / Q000662:veterinary; D011972:Receptor, Insulin / Q000032:analysis / Q000235:genetics; D017451:Receptors, Somatomedin / Q000032:analysis / Q000235:genetics; D011986:Receptors, Somatotropin / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary
D017931:DNA Primers; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D017451:Receptors, Somatomedin; D011986:Receptors, Somatotropin; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D004247:DNA; D011972:Receptor, Insulin