Plasma profiles of somatotropin and IGF-I in diary cows following application of two preparations of recombinant bovine somatotropin in a sustained release vehicle.
Milk production, plasma bovine somatotropin (bST) and insulin-like growth factor I (IGF-I) were measured in dairy cows following a single subcutaneous injection of a slowly released preparation of either recombinant enterokinase linker bST (somidobove: 640 mg) or recombinant methionyl bST (sometribove: 500 mg). There was a 3-7-fold increase in plasma bST concentrations during the first three postinjection hours in cows treated with both sometribove (from 3.4 +/- 0.8 to 11.2 +/- 3.0 ng ml-1) or somidobove (from 2.3 +/- 0.3 to 17.5 +/- 2.6 ng ml-1). In the next 8 days the bST concentration in the bST-treated cows varied, but was still significantly increased above the controls. In the following days, the concentrations of bST did not differ from the controls. Plasma concentrations of IGF-I increased nearly 2-fold as early as 24 h following recombinant bST administration and then continued to rise so that by 48 h postinjection they were nearly four times higher (control 16.2, bST-treated 61.7 ng ml-1). From 48 h after sometribove injection, IGF-I concentrations remained at a plateau (varying between 60.4 and 85.7 ng ml-1) till day 11. Then it decreased slowly, but still remained higher on day 14 than those in placebo-treated cows (44.4 +/- 17.8 ng ml-1 in bST-treated animals; 12.2 +/- 7.5 ng ml-1 in the controls). Although IGF-I level was increasing in all bST-treated animals, the absolute IGF-I increase was not related to the increase in milk production.
Slaba
J
J
Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic.
Krejcí
P
P
Skarda
J
J
Huybrechts
L M
LM
Decuypere
E
E
Herrmann
H
H
D000818:Animals; D002417:Cattle; D003692:Delayed-Action Preparations; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007774:Lactation / Q000187:drug effects; D008892:Milk / Q000502:physiology; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics
D003692:Delayed-Action Preparations; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone