1. Insulin-like growth factors-I and -II, somatotropin, prolactin, and placental lactogen are not acute effectors of lipolysis in ruminants.
- Author
-
Houseknecht KL, Bauman DE, Vernon RG, Byatt JC, and Collier RJ
- Subjects
- Adipose Tissue drug effects, Adipose Tissue metabolism, Adipose Tissue physiology, Adrenergic beta-Agonists pharmacology, Animals, Cattle physiology, Dose-Response Relationship, Drug, Female, Homeostasis drug effects, Homeostasis physiology, Isoproterenol pharmacology, Lactation physiology, Lipolysis physiology, Male, Pregnancy, Scotland, Sheep physiology, United States, Cattle metabolism, Growth Hormone pharmacology, Insulin-Like Growth Factor I pharmacology, Insulin-Like Growth Factor II pharmacology, Lipolysis drug effects, Placental Lactogen pharmacology, Prolactin pharmacology, Sheep metabolism
- Abstract
The acute regulation of lipolysis in the adipose tissue of ruminants was evaluated with lactating cows (n = 4) and growing ewe lambs (n = 11). Subcutaneous adipose tissue was obtained by biopsy or at slaughter and was incubated with varying concentrations of biologically active insulin-like growth factors-I and -II (IGF-I, IGF-II), somatotropin (ST), prolactin (PRL), or placental lactogen (PL) to determine the effect of these hormones on lipolysis. Complimentary studies were conducted to examine the effects of IGF-I and IGF-II on the acute regulation of lipolysis in adipose tissue from lactating ewes and wethers under a variety of incubation conditions. Isoproterenol (ISO), a beta-adrenergic agonist known to rapidly stimulate lipolysis, was used as a positive control. Incubation with ISO for 3 hr resulted in a significant increase in the rates of lipolysis. However, there was no stimulation of lipolysis over the 3-hr incubation at any concentration or under any conditions for IGF-I or IGF-II. Furthermore, ST, PRL, or PL had no acute effects on the rates of lipolysis in adipose tissue. These data demonstrate that IGF-I, IGF-II, ST, PRL, and PL are not acute effectors of the lipolytic rate in the adipose tissue of ruminants.
- Published
- 1996
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