title: Administration of porcine somatotropin by a sustained-release implant: effect on follicular growth, concentrations of steroids and insulin-like growth factor I, and insulin-like growth factor binding protein activity in follicular fluid of control, lean, and obese gilts.
abstract: Prepubertal gilts of control (n = 30), obese (n = 30), or lean (n = 29) genetic lines were implanted with no, one, or two implants of porcine somatotropin (pST, each delivers 2 mg/d) for 6 wk starting at 160 d of age to determine whether pST affects ovarian function. At 4 mg/d, pST increased (P < .01) numbers of 4.0- to 6.9-mm (medium) follicles but not (P > .10) numbers of 1.0- to 3.9-mm (small) follicles per gilt. Both doses of pST increased (P < .01) serum and follicular fluid (FFL) concentrations of IGF-I and activity of IGF binding protein (IGFBP)-3 and 36-kDa IGFBP in all three lines; IGFBP-3 was the predominant IGFBP. In comparison, binding activity of IGFBP-2 was decreased (P < .01) in serum by 4 mg of pST but increased (P < .05) in FFL by 4 mg of pST. Lean gilts had lower (P < .05) serum concentrations of IGF-I and less (P < .05) total binding activity of IGFBP than control and obese gilts. Concentrations of estradiol in FFL of small and medium follicles tended (P < .08) to be increased by 2 mg/d of pST, whereas FFL concentrations of progesterone were unaffected by pST. Obese and control gilts had twofold greater (P < .05) FFL progesterone concentrations than lean gilts. We conclude that sustained-release implants of pST can stimulate follicular growth, increase concentrations of IGF-I in serum and FFL, and increase IGFBP activity in serum of genetically divergent lines of gilts without an adverse effect on ovarian function.
authors.affiliation: U. S. Meat Animal Res. Center, Clay Center, NE 68933.
authors.forename: S E
authors.initials: SE
authors.lastname: Echternkamp
authors.forename: L J
authors.initials: LJ
authors.lastname: Spicer
authors.forename: J
authors.initials: J
authors.lastname: Klindt
authors.forename: R K
authors.initials: RK
authors.lastname: Vernon
authors.forename: J T
authors.initials: JT
authors.lastname: Yen
authors.forename: F C
authors.initials: FC
authors.lastname: Buonomo
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000032:analysis; D003692:Delayed-Action Preparations; D004343:Drug Implants; D004958:Estradiol / Q000032:analysis; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry*; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008024:Ligands; D009765:Obesity / Q000235:genetics / Q000503:physiopathology / Q000662:veterinary; D006080:Ovarian Follicle / Q000187:drug effects* / Q000502:physiology; D011374:Progesterone / Q000032:analysis; D013552:Swine / Q000235:genetics / Q000502:physiology*; D013553:Swine Diseases / Q000235:genetics / Q000503:physiopathology
chemical_list: D002352:Carrier Proteins; D003692:Delayed-Action Preparations; D004343:Drug Implants; D018969:Insulin-Like Growth Factor Binding Proteins; D008024:Ligands; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone