Furthermore, synthetic progestin ‘norgestrel’ has been proven as a neuroprotective agent in the retinitis pigmentosa, likely throughout the increase of growth factors, such as basic fibroblast growth factor (bFGF) and leukemia inhibitory factor (LIF) in the retina, favoring the upregulation of pro-survival and downregulation of apoptotic pathways and reduction of microglial pro-inflammatory activity (Doonan et al., 2011; Roche et al., 2016). Here, LIF is linked to retinitis pigmentosa.