Steroidogenic Activity, Insulin-Like Growth Factor-I Production, and Proliferation of Granulosa and Theca Cells Obtained from Dominant Preovulatory and Nonovulatory Follicles during the Bovine Estrous Cycle: Effects of Low-Density and High-Density Lipoproteins1

Abstract

The role of high- and low-density lipoproteins (HDL and LDL) in regulating steroidogenic activity, cellular viability and proliferation, and insulin-like growth factor-I (IGF-I) production was examined in granulosa and theca cells from dominant preovulatory (DO) and nonovulatory (DNO) bovine follicles. Follicles were obtained from pluriparous nonlactating beef cows at ovariectomy 24 h after administration of a luteolytic dose of prostaglandin F2 alpha (DO) or during the first follicular wave on Days 5-8 of the estrous cycle (DNO). Lipoprotein effects on hormone production (ng/1.5 x 10(5) viable cells) and cell viability were studied in serum-free, defined medium containing LH and FSH (granulosa) or LH only (theca). During late stages (96-144 h) of culture, HDL in the presence of gonadotropins increased (p < 0.001) the production of progesterone by granulosa and theca cells and the production of IGF-I by granulosa cells. LDL did not stimulate granulosa or thecal progesterone synthesis and attenuated HDL-stimulated progesterone production by both cell types. Gonadotropin stimulation of terminal synthetic pathways was either attenuated (granulosa estradiol production) by addition of lipoproteins or maximally stimulated (theca cell androstenedione production) by a combination of LDL and HDL. Both lipoproteins increased (p < 0.05) granulosa cell viability in both follicle types, and a marked proliferation (p < 0.001) of steroidogenically inactive theca cells was observed from DO but not DNO follicles. Proliferation potential appeared to be switched off during the late stages of maturation of DNO follicles and switched on after induced luteal regression and rescue of DO follicles.

Effect of dietary conjugated linoleic acid (CLA) on the metabolism and reproduction of dairy cows

“…A positive trend for HDL and LDL levels was also recorded in the follicular fluid of the cows fed CLA (P <0.1). Since in vitro studies have shown that both, HDL and LDL increase granulosa cells viability and the production of progesterone and IGF-I by the luteal cells (Bao et al, 1995;1997), results corroborate the hypothesis of a positive effect of dietary supplementation of CLA on reproduction. In agreement with a previous study (Castaneda-Gutierrez et al, 2007), plasma and follicular fluid IGF-I levels were higher in the CLA treated cows (P <0.05) (Figures 4 and 5).…”

“…Moreover, CLA increased the plasma lipoprotein concentrations in cattle (Trevisi et al, 2008). In vitro studies have demonstrated that high and low density lipoproteins (HDL and LDL) generally promote bovine granulosa cell viability (Bao et al, 1995) and stimulate greater progesterone and IGF-I secretions in bovine luteal cell cultures (Bao et al, 1997). The proposed anti-inflammatory effects of CLA may then protect the anti-oxidant paraoxonase1 (PON) from inactivation (Su et al, 2003).…”

9‐cis‐retinoic acid during in vitro maturation improves development of the bovine oocyte and increases midkine but not IGF‐I expression in cumulus‐granulosa cells

“…Nevertheless, the detailed pattern of mRNA expression and production of IGF-I in bovine follicles remains controversial. Cattle granulosa cells were reported to produce IGF-I in vitro (Spicer et al, 1993;Bao et al, 1995;Chamberlain, 1998, 2000;Sirotkin et al, 1998), but one study concluded that IGF-I is not produced by these cells (Gutierrez et al, 1997). In the same way, IGF-I mRNA was detected in bovine granulosa cells (Spicer et al, 1993;Spicer and Echternkamp, 1995;Yuan et al, 1998;Schams et al, 1999), although other works report null or weak IGF-expression in only 17% of the follicles evaluated (Perks et al, 1999).…”

The effects of LH on progesterone production by cell subpopulations isolated from early and late luteal phase goat corpora lutea

“…3β-Hydroxysteroid dehydrogenase (3β-HSD) is an enzyme that catalyzes the synthesis of progesterone from pregnenolone (5). Thus, steroidogenic cells can be identified by the determination of 3β-HSD activity during the cell counting process (6). In goats, as in other mammals, the luteal cell size progressively increases as more and more small-sized cells achieve the process of cell differentiation to form large luteal cells during the progress of the luteal phase (2,3).…”