Endocrine Abstracts

Non-selective hormonal therapy with estradiol attenuates metabolic dysfunction associated to post menopause. However, its effectiveness decreases over-time, and is associated hormone-dependent cancers development. Conversely, beta-type estradiol receptor (ERβ) activation has been showing promising outcomes in basic research, improving hepatic response to energy overload insult, in addition to presenting antitumor action. Therefore, we evaluated the ability of ERβ to promote metabolic effects on hepatocytes, focusing on mitochondrial function. AML12 cells were submitted to high glucose (20 mM) plus palmitate (200 µ M), and the effect of ERβ activation with diarilpropionitrile (0.1 or 1 nM, 24h) was evaluated through Extracellular Flux Analysis. We modulated different electron transport chain complexes to assess basal, ATP-linked, maximal, reserve capacity, and non-mitochondrial respiration. Mitochondrial network volumes and shape were evaluated through fluorescence microscopy. The substrate commitment assay evaluated the ability of cells to shift the use of carbohydrates, lipids, or aminoacids when target points of entrance into mitochondria are inhibited sequentially. The substrate capacity assay assesses the maximal ability of cells to oxidize one type of substrate. We also checked for acute responses to adrenaline, as a physiological signal, compared outcomes, including the production of ketone bodies and lipid oxidation. Overload with palmitate plus high glucose affected basal, ATP-linked and maximal respiration, as well as reserve capacity (maximal respiration difference from basal) of mitochondria. ERβ activation treatment did not change these parameters. Mitochondrial morphology also didn’t present expressive changes after treatment. These results indicate that ERβ activation doesn’t overtly alter metabolic fluxes nor morphology under basal conditions. However, challenging these cells with physiological or pharmacological stimuli, the responses significatively changed. The hepatocytes present higher commitment to individual substrate oxidation, decreasing the ability to shift the source of ATP. This result was verified modulating pyruvate, glutamine, or palmitate entrance into mitochondria. The capacity to oxidize these substrates didn’t change after treatment, except for pyruvate, meaning that these cells presented a decreased ability to exclusively oxidize carbohydrates. Finally, physiological responses were also different. In this assay, hepatocytes submitted to overload decreased the adrenergic response, and the treatment recovered to control levels. Basal production of ketone bodies followed the same pattern, increasing in energy overload conditions, and returning to control levels after treatment. In conclusion, ERβ activation made hepatocytes respond differently when challenged with pharmacological and physiological stimuli. Our results uncover the potential of selective ERβ modulation as an alternative to estradiol or ERA activation-based therapies for metabolic diseases.