PARENT SESSION

(133) AMPK ACTIVATION INCREASES GLUCOSE UPTAKE, DECREASES APOPTOSIS AND IMPROVES PREGNANCY OUTCOME IN EMBRYO EXPOSED TO HIGH IGF-1 CONCENTRATIONS.

Moley, Kelle¹, Wyman, Amanda¹, Eng, Grace¹, Chi, Maggie¹, ¹ Washington University School of Medicine, St. Louis, MO

ABSTRACT- Prior studies from our laboratory have demonstrated that exposure to high concentrations of IGF-1 or blockade of the IGF-1 receptor lead to insulin/IGF-1 resistance in the murine blastocyst, which results in increased blastocyst apoptosis and poor pregnancy outcome. In this study we hypothesize that improvement in insulin sensitivity with the AMPK activator metformin may directly improve insulin signaling in the blastocyst and rescue the blastocysts from adverse outcomes. Two cell embryos were cultured for 72 hours in either control media, media with high concentrations of IGF-1 (HI; 200nM), media with IGF-1 and metformin (HI-MT; 25ug/ml), or media with metformin alone (MT). As previously shown, insulin-stimulated 2-deoxyglucose (DG) uptake was significantly decreased in single blastocysts (n=55) cultured in high IGF-1 as compared to control embryos (n=47; p<0.05). Metformin reversed the effect of HI and normalized DG uptake in the embryos cultured in HI-MT (n=55; p<0.01). In addition, metformin reversed the adverse effect of HI on apoptosis as measured by TUNEL-positive nuclei/embryo (p<0.05 HI vs HI-MT). Both DG uptake and TUNEL positive percentage in the HI-MT exposed embryos were not significantly different than control or metformin alone. Also, HI led to changes in metabolites in individual blastocysts suggesting insulin resistance. These include decreased fluxes in fructose-1,6-phosphate and AMP concentrations in single blastocysts in response to acute insulin stimulation. The addition of metformin to the HI culture reversed this decrease and normalized changes in these two metabolites. To test whether this effect was due to AMPK activation, another compound was tested. AICAR which also stimulates AMPK activity, reversed the effect of HI on insulin stimulated DG uptake, apoptosis, and metabolite changes. Finally, embryos cultured in control media, HI, or HI-MT were transferred into pseudopregnant mice. Metformin rescued the HI embryos by improving implantation rate (31%(HI) to 77%(HI-MT)) and decreasing resorption rates (29%(HI) to 17%(HI-MT)) at embryonic day 14.5. These studies suggest that this improvement in insulin-stimulated glucose uptake with AMPK activation may be a mechanism for improved pregnancy outcomes in PCOS patients treated with metformin.

KEY WORDS: AMPK, glucose uptake, apoptosis, insulin resistance