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Contents The LH surge induces functional and morphological changes in granulosa cells. Mechanistic target of rapamycin ( mTOR) is an integrator of signalling pathways in multiple cell types. We hypothesized that mTOR kinase activity integrates and modulates molecular pathways induced by LH in granulosa cells during the preovulatory period. Cows were ovariectomized and granulosa cells collected at 0, 3, 6, 12 and 24 hr after Gn RH injection. While RHEB mRNA levels increased at 3 and 6 hr, returning to basal levels by 12 hr after Gn RH treatment, RHOA mRNA levels increased at 6 hr and remained high thereafter. Western blot analyses revealed increased S6K phosphorylation at 3 and 6 hr after Gn RH injection. Similarly, mRNA levels of ERK1/2, STAR and EGR-1 were higher 3 hr after Gn RH treatment. Rapamycin treatment inhibited mTOR activity and increased AKT activity, but did not alter ERK1/2 phosphorylation and EGR1 protein levels in cultured bovine granulosa cells. Rapamycin also inhibited LH-induced increase in EREG mRNA abundance in granulosa cells in vitro. However, intrafollicular injection of rapamycin did not suppress ovulation. These findings suggest that mTOR is involved in the control of EREG expression in cattle, which may be triggered by LH surge stimulating RHEB and S6K activity. [ABSTRACT FROM AUTHOR]

Contents The anti-Müllerian hormone ( AMH) is an important marker of ovarian reserve and for predicting the response to superovulatory treatments in several species. The objective of this study was to investigate whether AMH and its receptor ( AMHR2) are regulated in bovine granulosa cells during follicular development. In the first experiment, granulosa cells were retrieved from the two largest follicles on days 2 (before), 3 (at the expected time) or 4 (after deviation) of follicular wave. In the second experiment, four doses of FSH (30, 30, 20 and 20 mg) or saline were administered twice a day starting on Day 2 of the first follicular wave of the cycle. Granulosa cells and follicular fluid were collected from the two largest follicles 12 h after the last injection of FSH or saline. AMH mRNA abundance was similar in granulosa cells of the two largest follicles (F1 and F2) before deviation (Day 2), but greater in dominant ( DF) than subordinate follicles ( SF) at the expected time (Day 3) and after (Day 4) deviation (p < 0.05). In experiment 1, AMH mRNA levels declined in both DF and SF near the expected time and after deviation when compared to before deviation. There was no difference in AMHR2 mRNA levels before and during follicular deviation (p > 0.05), but they tended to be greater in DFs than SFs (p < 0.1) after deviation. Experiment 2 showed that AMH and AMHR2 mRNA in granulosa cells and AMH protein abundance in follicular fluid were similar (p > 0.05) between both co-dominant follicles collected from the FSH-treated cows. These findings indicate the followings: AMH mRNA levels decrease in both DFs and SFs during follicular deviation; granulosa cells from heathy follicles express more AMH mRNA compared to subordinate follicles undergoing atresia and FSH stimulates AMH and AMHR2 mRNA expression in granulosa cells of co-dominant follicles. [ABSTRACT FROM AUTHOR]

Contents [ABSTRACT FROM AUTHOR]