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Insulin‐Like Growth Factor‐1 Regulates the Expression of Luteinizing Hormone Receptor and Steroid Production in Bovine Granulosa Cells
Author(s) -
Rawan AF,
Yoshioka S,
Abe H,
Acosta TJ
Publication year - 2015
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/rda.12486
Subject(s) - medicine , endocrinology , luteinizing hormone , follicular phase , ovulation , insulin like growth factor , androstenedione , biology , ovary , growth factor , steroid hormone , follicle , ovarian follicle , follicular fluid , receptor , hormone , oocyte , androgen , microbiology and biotechnology , embryo
Contents Luteinizing hormone LH plays important roles in follicular maturation and ovulation. The effects of LH are mediated by LH receptor ( LHR ) in the ovary. However, the factors that regulate the expression of LHR in bovine granulosa cells ( GC s) are not well known. Insulin‐like growth factor‐1 ( IGF ‐1) is known to play a key role in the acquisition and maintenance of functional dominance. To better understand the roles of LHR expression and IGF ‐1, we conducted three experiments to determine (i) mRNA expression of LHR in the GC s of developing follicles, (ii) the effects of IGF ‐1 on LHR mRNA expression in cultured GC s and (iii) the effects of IGF ‐1 on estradiol (E2), progesterone (P4) and androstenedione (A4) production by non‐luteinized GC s. In experiment 1, small follicles (<6 mm Ø) expressed lower levels of LHR than mid‐sized follicles (6–8 mm Ø) and large follicles (≥9 mm Ø) expressed the highest levels of LHR mRNA (p < 0.05). In experiment 2, IGF ‐1 (1 and 100 ng/ml) increased (p < 0.05) the expression of LHR mRNA in GC s from small and large follicles. In experiment 3, IGF ‐1 (0.1–100 ng/ml) increased A4 and E2 in GC s from both small and large follicles but increased P4 only in large follicles. IGF ‐1 in combination with LH (0.1 and 1 ng/ml) increased P4 and A4 in large follicles, and increased E2 and A4 in GC s of small follicles. These findings strongly support the concept that IGF ‐1 upregulates LHR mRNA expression as well as A4 and E2 production in GC s and that IGF ‐1 is required for determining which follicle becomes dominant and acquires ovulatory capacity.