Concentrations of insulin-like growth factor I and steroids in follicular fluid of preovulatory bovine ovarian follicles: effect of daily injections of a growth hormone-releasing factor analog and(or) thyrotropin-releasing hormone.
To determine whether long-term administration of growth hormone (GH)-releasing factor (GRF) and(or) thyrotropin-releasing hormone (TRH) alters ovarian follicular fluid (FFL) concentrations of insulin-like growth factor-I (IGF-I), progesterone, and estradiol (E2), and follicular growth, Friesian x Hereford heifers (n = 47; 346 +/- 3 kg) were divided into the following four groups: control (vehicle; n = 11); 1 micrograms GRF (human [Des NH2 Tyr1, D-Ala2, Ala15] GRF [1-29]-NH2).kg-1 BW.d-1 (n = 12); 1 microgram TRH.kg-1 BW.d-1 (n = 12); or GRF + TRH (n = 12). Daily injections (s.c.) continued for 86 d. On d 89, heifers that had been synchronized were slaughtered and ovaries were removed. Follicles were grouped by magnitude of diameter into the three following sizes: 1 to 3.9 mm (small, n = 55), 4.0 to 7.9 mm (medium, n = 63), and greater than or equal to 8 mm (large, n = 71). Growth hormone-releasing factor and(or) TRH did not affect (P greater than .10) IGF-I concentrations in FFL of any follicle size group. Growth hormone-releasing factor increased (P less than .06) size (means +/- pooled SE) of large follicles (14.7 vs 13.0 +/- .6 mm). Growth hormone-releasing factor also increased (P less than .05) progesterone concentrations 4.4-fold above controls in FFL of medium-sized follicles but had no effect on progesterone in FFL of the small or large follicles. Thyrotropin-releasing hormone did not alter FFL progesterone or E2 concentrations in any follicle size group. We conclude that the GRF and(or) TRH treatments we employed did not affect intra-ovarian IGF-I concentrations, but GRF may alter steroidogenesis of medium-sized follicles and growth of large follicles.
Spicer
L J
LJ
Dept. of Anim. Sci., Oklahoma State University Agricultural Experiment Station, Stillwater 74078.
Enright
W J
WJ
D000818:Animals; D002417:Cattle / Q000502:physiology*; D004958:Estradiol / Q000032:analysis; D005260:Female; D015571:Follicular Fluid / Q000737:chemistry*; D013006:Growth Hormone / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D016018:Least-Squares Analysis; D003341:Luteolysis; D006080:Ovarian Follicle / Q000187:drug effects*; D011374:Progesterone / Q000032:analysis; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D011374:Progesterone; D004958:Estradiol; D013973:Thyrotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone