Media composition and O2 levels determine effects of 17β-Estradiol on mitochondrial bioenergetics and cellular reactive oxygen species.

Estradiol (E2) and selective estrogen receptor modulators (SERMs) have broad-ranging cellular effects that include mitochondrial respiration and reactive oxygen species (ROS) metabolism. Many of these effects have been studied using cell culture models. Recent advances have revealed the extent to which cellular metabolism is affected by the culture environment. Cell culture media with metabolite composition similar to blood plasma (e.g. Plasmax, HPLM) alter cellular behaviours including responses to drugs. Similar effects have been observed with respect to O2 levels in cell culture. Given these observations, we set out to determine whether the effects of E2 and SERMs are also influenced by media composition and O2 level during cell culture experiments. We analyzed mitochondrial network characteristics, cellular oxygen consumption rates, and cellular H2O2 production in C2C12 myoblasts growing in physiologic (5%) or standard cell culture (18%) O2 and in physiologic (Plasmax) or standard cell culture (DMEM) media. The cell culture conditions affected all measured parameters under basal conditions and changed how cells responded to E2 or SERMs. These results indicate that the effects of E2 and SERMs on various aspects of cell physiology strongly depends on growth conditions, which in turn emphasizes the need to consider this carefully in cell culture experiments.