Acetoacetate and β-hydroxybutyrate reduce mouse embryo viability via differential metabolic and epigenetic mechanisms

Abstract

Research question: Does the ketone acetoacetate (AcAc) alone, or combined with β-hydroxybutyrate (βOHB), impact mouse embryo development, metabolism, histone acetylation and viability?

Design: Pronucleate mouse oocytes were cultured in vitro in G1/G2 media supplemented with ketones (AcAc or AcAc + βOHB) at concentrations representing those in maternal serum during pregnancy (0.04 mmol/l AcAc, 0.1 mmol/l βOHB), standard diet consumption (0.1 mmol/l AcAc, 0.25 mmol/l βOHB), ketogenic diet consumption (0.8 mmol/l AcAc, 2 mmol/l βOHB) and diabetic ketoacidosis (2 mmol/l AcAc, 4 mmol/l βOHB). Day 5 blastocysts were assessed for cell allocation, glucose metabolism and histone acetylation. Day 4 blastocysts exposed to 0.8 mmol/l AcAc + 2 mmol/l βOHB were transferred to standard-fed recipient females, and E14.5 fetal and placental development assessed.

Results: Exposure to 2 mmol/l AcAc or 0.8 mmol/l AcAc + 2 mmol/l βOHB did not impair blastocyst development, but significantly increased glucose consumption (P = 0.001 each), lowered glycolytic flux (P = 0.01, P < 0.001) and elevated trophectoderm (TE) histone 3 lysine 27 acetylation (H3K27ac; P < 0.001 each) compared with unexposed controls. Preimplantation AcAc + βOHB exposure reduced post-implantation fetal development by 25% (P = 0.037), and delayed female-specific fetal limb development (P = 0.019) and estimated fetal age (P = 0.019) compared with controls.

Conclusion: Preimplantation exposure to ketones affects underlying metabolism and histone acetylation in blastocysts that are associated with persistent, female-specific perturbations in fetal development. A periconceptional diet that elevates ketone concentrations may impair human embryonic viability.

Keywords: Acetylation; Blastocyst; Development; Ketogenic diet; Ketone; Nutrient.