Objective: Adenosine monophosphate-activated protein kinase (AMPK) is a cellular energy sensor whose phosphorylation increases energy production. We sought to evaluate the placenta-specific effect of AMPK activation on the handling of nutrients required for fetal development.
Methods: Explants were isolated from term placenta of 29 women (pregravid body mass index: 29.1 ± 9.9 kg/m2) and incubated for 24 hours with 0 to 100 µmol/L resveratrol or 0 to 1 mmol/L of 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR). Following treatment, uptake and metabolism of radiolabeled fatty acids and glucose were measured. Phosphorylation of AMPK was measured by Western blotting. Adenosine diphosphate (ATP) production was assessed using the mitochondrial ToxGlo assay kit. P < .05 was considered statistically significant.
Results: Resveratrol and AICAR increased AMPK phosphorylation in human placental explants. Exposure to resveratrol decreased the uptake of polyunsaturated fatty acids, arachidonic acid, and docosahexaenoic acid at 100 µmol/L ( P < .0001). Fatty acid oxidation was decreased by 100 µmol/L ( P < .05) resveratrol, while esterification was unchanged. Resveratrol decreased glucose uptake at the 50 and 100 µmol/L doses ( P < .05). Glycolysis was not significantly affected. AICAR had similar effects, decreasing fatty acid uptake and glycolysis ( P < .05). Production of ATP declined at doses found to decrease nutrient metabolism ( P < .05).
Conclusions: Activation of AMPK in the human placenta leads to global downregulation of metabolism, with mitotoxicity induced at the doses of resveratrol and AICAR used to activate AMPK. Although activation of this pathway has positive metabolic effects on other tissues, in the placenta there is potential for harm, as inadequate placental delivery of critical nutrients may compromise fetal development.
Keywords: AICAR; AMP kinase; metabolism; resveratrol; trophoblasts.