Regulation of mitochondrial substrate utilization by estrone (E1), 17² estradiol (E2), and estriol (E3) in the hepatic mouse AML12 cell lineage.

Abstract

Estrogens are essential for several regulatory functions, especially in sexual maturity, reproduction, and post-menopause. In addition, these hormones play a role in energy metabolism. This protective effect is clearly observed in humans and animal models with low levels of estradiol (E2), where E2 replacement reverses several parameters related to the risk of diabetes and cardiovascular disease development.E2 is the major circulating estrogen in females at reproductive age. Thus, its effects on mitochondrial function in cells with high metabolic relevance, such as hepatocytes, have already been explored. E2 is, in fact, able to improve oxidative phosphorylation and decrease oxidative stress, with a potential benefit in aging and age-related metabolic diseases. However, hormone replacement therapy with E2, especially in the postmenopausal period, has temporary benefits in addition to risks associated with the development of breast, endometrium, and ovary hormone-responsive tumors.Besides E2, other estrogens are also present in circulation, such as estrone (E1) and estriol (E3); E1 at having higher levels post menopause and E3 during pregnancy. However, it is surprising to note that so far there are an extremely limited number of studies investigating the involvement of E1 and E3 in mitochondrial function of hepatocytes, and no elucidation of the mechanisms involved are present in the literature.Thus, considering that the liver plays a crucial role in handling substrates that affect on mitochondrial function, elucidating the effects of E1 and E3 on hepatocyte oxidative phosphorylation would be of great interest in health, supplying essential information for the development of new therapeutic approaches for metabolic diseases.To attend this purpose, we will evaluate whether acute and/or chronic treatment with E1, E2, or E3 modify the use of substrates by intact AML12 hepatocyte cells or directly by mitochondria in permeabilized cells using cellular and mitochondrial oxygen consumption analysis. In addition, the mechanisms associated with these modifications will be investigated by Western Blots and gene expression evaluations by quantitative PCR. Finally, mitochondrial membrane potentials, hydrogen peroxide production and calcium uptake will be analyzed.