Trolox and recombinant Irisin as a potential strategy to prevent neuronal damage induced by random positioning machine exposure in differentiated HT22 cells

Neuronal death could be responsible for the cognitive impairments found in astronauts exposed to spaceflight, highlighting the need to identify potential countermeasures to ensure neuronal health in microgravity conditions. Therefore, differentiated HT22 cells were exposed to simulated microgravity by random positioning machine (RPM) for 48 h, treating them with a single administration of Trolox, recombinant irisin (r-Irisin) or both. Particularly, we investigated cell viability by MTS assay, Trypan Blue staining and western blotting analysis for Akt and B-cell lymphoma 2 (Bcl-2), the intracellular increase of reactive oxygen species (ROS) by fluorescent probe and NADPH oxidase 4 (NOX4) expression, as well as the expression of brain-derived neurotrophic factor (BDNF), a major neurotrophin responsible for neurogenesis and synaptic plasticity. Although both Trolox and r-Irisin manifested a protective effect on neuronal health, the combined treatment produced the best results, with significant improvement in all parameters examined. In conclusion, further studies are needed to evaluate the potential of such combination treatment in counteracting weightlessness-induced neuronal death, as well as to identify other potential strategies to safeguard the health of astronauts exposed to spaceflight.