Active immunization of pigs against growth hormone-releasing factor: effect on concentrations of growth hormone and insulin-like growth factor 1.
Cyclic gilts (96 +/- 1 kg) were used to determine the effect of active immunization against growth hormone-releasing factor GRF(1-29)-NH2 on concentrations of growth hormone (GH) and insulin-like growth factor 1 (IGF-1). Gilts were immunized against GRF conjugated to human serum albumin (GRF-HSA, n = 5) or HSA alone at 180 d of age (wk 0). Booster doses were administered at wk 9 and 13. Seven days after the second booster (wk 14), blood samples were collected at 15-min intervals for 6 h before feeding and 30, 60, 120, 180 and 240 min after feeding. Eight days after the second booster, all gilts were administered a GRF analog, [desNH2Tyr1,Ala15]-GRF(1-29)-NH2, followed by an opioid agonist, FK33-824. Blood samples were collected at 15-min intervals from -30 to 240 min after injection. Immunization against GRF-HSA resulted in antibody titers, expressed as dilution required to bind 50% of [125I]GRF, ranging from 1:11,000 to 1:60,000 (wk 11 and 14); binding was not detectable or was less than 50% at 1:100 in HSA gilts (P less than .05). Episodic release of GH was abolished by immunization against GRF-HSA (P less than .05). Mean GH was decreased (P less than .07), but basal GH concentrations were not altered (P greater than .15) by immunization against GRF-HSA. Serum concentrations of IGF-1 were similar at wk 0, but concentrations were lower in GRF-HSA than in HSA gilts (P less than .05) at wk 14.(ABSTRACT TRUNCATED AT 250 WORDS)
Armstrong
J D
JD
Dept. of Anim. Sci., North Carolina State Univ., Raleigh 27695-7621.
Esbenshade
K L
KL
Johnson
J L
JL
Coffey
M T
MT
Heimer
E
E
Campbell
R M
RM
Mowles
T
T
Felix
A
A
D000818:Animals; D000917:Antibody Formation; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D013007:Growth Hormone-Releasing Hormone / Q000276:immunology*; D007110:Immunity, Active; D007114:Immunization / Q000662:veterinary*; D007117:Immunization, Secondary; D007334:Insulin-Like Growth Factor I / Q000032:analysis*; D011897:Random Allocation; D013002:Somatomedins / Q000032:analysis*; D013552:Swine / Q000276:immunology / Q000378:metabolism*
D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone