Insulin-like growth factors-I and -II, somatotropin, prolactin, and placental lactogen are not acute effectors of lipolysis in ruminants.
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.
Houseknecht
K L
KL
Department of Animal Science, Cornell University, Ithaca, NY, USA.
Bauman
D E
DE
Vernon
R G
RG
Byatt
J C
JC
Collier
R J
RJ
D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002417:Cattle / Q000378:metabolism* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D007774:Lactation / Q000502:physiology; D008066:Lipolysis / Q000187:drug effects* / Q000502:physiology; D008297:Male; D010928:Placental Lactogen / Q000494:pharmacology*; D011247:Pregnancy; D011388:Prolactin / Q000494:pharmacology*; D012606:Scotland; D012756:Sheep / Q000378:metabolism* / Q000502:physiology; D014481:United States
D000318:Adrenergic beta-Agonists; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D011388:Prolactin; D013006:Growth Hormone; D010928:Placental Lactogen; D007545:Isoproterenol