NFE2L2 and Parkinson disease: For example, CO is able to activate protective factors of PD, such as hypoxia-inducible factor 1α (HIF 1α) and nuclear factor erythroid 2-related factor 2 (Nrf2), inhibit poly (ADP-ribose) polymerase (PARP) cleavage, reduce caspase-3 activation, inhibit cell death, and activate the release of adenosine by astrocytes (Zhang et al., 2011; Stein et al., 2012; Choi et al., 2016; Queiroga et al., 2016; Wang et al., 2011).