Follicle Selection in Cattle: Role of Luteinizing Hormone

• Published in: Biology of reproduction Vol. 64; no. 1; pp. 197 - 205
• Main Authors: GINTHER, O. J, BERGFELT, D. R, BEG, M. A, KOT, K
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01-01-2001
• Subjects: Animals; Biological and medical sciences; Cattle - physiology; Estradiol - analysis; Female; Follicular Fluid - chemistry; Fundamental and applied biological sciences. Psychology; Hormone metabolism and regulation; Insulin-Like Growth Factor Binding Protein 2 - analysis; Insulin-Like Growth Factor I - analysis; Luteinizing Hormone - blood; Luteinizing Hormone - physiology; Mammalian female genital system; Ovarian Follicle - anatomy & histology; Ovarian Follicle - chemistry; Ovarian Follicle - physiology; Progesterone - administration & dosage; Progesterone - analysis; Progesterone - pharmacology; Vertebrates: reproduction; Estrogen; Ox; Gonadotropin; Estradiol; Ovarian hormone; Insulin like growth factor binding protein; Ovary; Vertebrata; Insulin like growth factor; Mammalia; Adenohypophyseal hormone; Female genital system; Luteinizing hormone; Female; Artiodactyla; Progesterone; Sex steroid hormone; Ovarian follicle; Ungulata; Follicle stimulating hormone; Oocyte maturation
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod64.1.197

The circulating concentrations of LH were reduced by administration of 50 mg of progesterone every 8 h for 72 h, beginning
when the largest follicle was 6.0 mm (experiment 1; n = 10). Progesterone treatment prevented the transient increase in LH
that accompanied deviation (partitioning into dominant and subordinate categories) in control heifers (n = 10). The reduced
LH concentrations were associated with reduced growth of the largest follicle, beginning a mean of 31 h after deviation, but
did not alter the time of deviation or the growth and regression of the second-largest follicle. In experiment 2, 0 mg (controls)
or 50 mg of progesterone was given every 8 h for three injections, beginning when the largest follicle was 7.0 mm (predeviation
group) or 9.0 mm (postdeviation group; n = 8 for each of the four groups). Blood samples from the jugular vein and follicular-fluid
samples from the two largest follicles were taken 8 h after the last treatment when the largest follicle was a mean of 8.7
mm in the predeviation group and 10.8 mm in the postdeviation group. In the controls, follicular-fluid concentrations of estradiol
and free insulin-like growth factor (IGF)-1 in the largest follicle and IGF binding protein (IGFBP)-2 in the second-largest
follicle were higher ( P < 0.05) in the postdeviation group than in the predeviation group. Progesterone treatment lowered ( P < 0.006) the circulating LH concentrations to a similar extent in both groups. In the predeviation group, progesterone treatment
did not have a significant effect on any of the characteristics of the largest follicle. In the postdeviation group, the largest
follicle of the progesterone-treated heifers had significant reductions in diameter and in follicular-fluid concentrations
of estradiol and free IGF-1. Follicular-fluid concentrations of immunoreactive inhibin were not different for any of the comparisons.
The results supported the hypothesis that LH has a positive effect on diameter of the largest follicle but not until after
the beginning of diameter deviation. In addition, the results indicated that LH is involved in the production of estradiol
by the largest follicle and that free IGF-1 concentrations increase in the largest follicle during deviation.