Effect of bovine somatotropin and food deprivation on beta-adrenergic and A1 adenosine receptor binding in adipose tissue of lactating cows.
Lactating Holstein cows were used to assess the effect of bovine somatotropin (bST; n = 8) and fasting (FAST; n = 4) on ligand binding to beta-adrenergic (BAR) and Type-1 adenosine (A1R) receptors in adipose tissue. Cows received exogenous bST (sometribove; 40 mg/d) or no hormone (control) for 4 d in a single-reversal design with a 7-d interval between treatment periods. Subcutaneous adipose tissue biopsies were taken on day 4 of each treatment. Eight d after the bST regimen, 4 cows were fasted for 3 d and adipose biopsies were taken. Ligand binding was quantified with a postnuclear, total adipose tissue membrane preparation (100,000 x g pellet). Binding to BAR and A1R was assessed with the antagonists [125I]iodocyanopindolol (ICP) and [3H]8-cyclopentyl-1,3-dipropylxanthine (DCPCX), respectively. The binding affinity (Kd) of BAR for ICP was not affected by bST but was enhanced by FAST; maximal binding (Bmax) was increased with bST treatment (P < 0.06) and reduced by FAST (61%, P < 0.01). Kd values for DCPCX binding to A1R were not changed by bST or FAST. bST did not affect Bmax for A1R; however, FAST reduced the Bmax by 38%. Data highlight the differential regulation of BAR and A1R by bST and FAST.
Houseknecht
K L
KL
Department of Animal Science, Cornell University, Ithaca, NY, USA.
Bauman
D E
DE
Carey
G B
GB
Mersmann
H J
HJ
D000273:Adipose Tissue / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D002417:Cattle / Q000378:metabolism* / Q000502:physiology; D005215:Fasting / Q000502:physiology; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D013006:Growth Hormone / Q000494:pharmacology*; D020120:Iodocyanopindolol; D007774:Lactation / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D008024:Ligands; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D011943:Receptors, Adrenergic, beta / Q000032:analysis / Q000378:metabolism*; D018047:Receptors, Purinergic P1 / Q000032:analysis / Q000378:metabolism*; D014970:Xanthines / Q000378:metabolism / Q000494:pharmacology
D000319:Adrenergic beta-Antagonists; D008024:Ligands; D011943:Receptors, Adrenergic, beta; D018047:Receptors, Purinergic P1; D014970:Xanthines; D020120:Iodocyanopindolol; D013006:Growth Hormone; C051360:1,3-dipropyl-8-cyclopentylxanthine; D010869:Pindolol; C108583:sometribove