Changes in growth hormone and luteinizing hormone following acute or chronic administration of an opioid agonist, FK33-824, in wethers.
Two experiments were conducted to determine the effect of acute or chronic administration of an opioid agonist, (D-Ala2,MePhe4,Met(O)5-ol)-enkephalin (FK33-824), on concentrations of growth hormone (GH) and LH in castrate sheep (wethers). In Exp. 1, we evaluated the effect of acute administration (two injections or infusion for 2 h) of FK33-824 on GH and LH. Wethers (31 +/- 1 kg; n = 12) received FK33-824 or saline via one of the three following routes of deliver: 1) i.v. (8 micrograms/kg) at 0 and 60 min (i.v., n = 4), 2) s.c. (16 micrograms/kg) at 0 and 60 min (s.c., n = 4), or 3) i.v. infusion (8 micrograms.kg-1.h-1) for 120 min (inf., n = 4) preceded by a single injection (8 micrograms/kg). Wethers received FK33-824 and saline on d 1 and 2 or d 2 and 1, respectively. Concentrations of GH were consistently elevated (P less than .05) by FK33-824 regardless of route of delivery. Infusion of FK33-824 for 120 min maintained GH concentrations greater (P less than .05) than pretreatment or those during infusion of saline. Average LH was decreased consistently by FK33-824, independent of its route of administration; episodic release of LH was suppressed. In Exp. 2, crossbred wethers (36 +/- 2 kg; n = 12) were used to determine the effect of chronic administration (s.c.) of FK33-824 on the concentrations of GH and LH and retention of N and energy.(ABSTRACT TRUNCATED AT 250 WORDS)
Armstrong
J D
JD
North Carolina State University, Raleigh 27695-7621.
Spears
J W
JW
D000818:Animals; D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin / Q000008:administration & dosage / Q000494:pharmacology*; D004734:Energy Metabolism; D005243:Feces / Q000737:chemistry; D013006:Growth Hormone / Q000097:blood*; D007262:Infusions, Intravenous / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D007279:Injections, Subcutaneous / Q000662:veterinary; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D012756:Sheep / Q000378:metabolism*
D005405:D-Ala(2),MePhe(4),Met(0)-ol-enkephalin; D007986:Luteinizing Hormone; D013006:Growth Hormone; D009584:Nitrogen