Mitochondrial Function Under Combined Oral Contraceptive Exposure in a Neuroblastoma Model: A Preliminary Investigation

Background: Endogenous estradiol/progesterone (E2/P4) regulates neuronal mitochondrial bioenergetics and redox balance. However, the effects of combined oral contraceptive (COC) steroids under physiologically relevant hormonal conditions remain poorly understood. Therefore, this study aims to investigate how COC steroids modulate mitochondrial function within the defined E2/P4 hormonal milieus. Methods: Human SH-SY5Y cells (Cytion) were starved for 48 h in Cytion medium without FBS and with 1% ITS, and then exposed for 48 h to six conditions: vehicle (F0); follicular-like E2/P4 (F1); luteal-like E2/P4 (F2); F1 + dienogest/ethinylestradiol (DNG/EE; F3); F2 + DNG/EE (F4); and DNG/EE alone (F5). The primary endpoints were mitochondrial membrane potential (JC-1 red/green ratio) and ROS (H2DCFDA/DCF); nitric oxide (DAF-FM) was also recorded. Hoechst 33342 nuclear fluorescence served both as a per-well proxy of cell number and as a proportionality factor for normalization. Results: Follicular- and luteal-like backgrounds were associated with distinct ΔΨm/ROS set-points. The addition of DNG/EE was accompanied by background-dependent shifts, generally characterized by higher DCF signals and lower JC-1 ratios relative to the vehicle, whereas DAF-FM did not reveal statistically robust changes in NO. Hoechst-based normalization preserved these patterns, suggesting that the observed effects likely reflect per-cell functional modulation rather than differences in cell number, although modest, background-dependent variations in proliferation were observed, with DNG/EE associated with a greater increase in ROS under follicular-like conditions and a more pronounced ΔΨm membrane potential in a luteal-like milieu. Conclusions: These findings suggest that neuroendocrine background may influence mitochondrial ΔΨm/ROS states in SH-SY5Y cells, with physiologically inspired E2/P4 milieus potentially shaping baseline conditions onto which COC components exert context-dependent effects at 48 h. These preliminary findings provide a standardized framework for subsequent image-based analyses of mitochondrial function.