GPX4 and depressive symptom measurement: On the other side, anxiety- and depression-like behaviour may be ameliorated by antioxidants via up-regulation of the sirtuin 1 (SIRT1)–nuclear factor erythroid 2-related factor 2 (Nrf2)–haeme oxygenase 1 (HO-1)–glutathione peroxidase 4 (Gpx4) axis [7].