RLN3 and psychiatric disorder: Therefore, previous reviews of the neurobiology of the NI and its relaxin-3 signaling system have focused on a likely role in stress and arousal (Ryan et al., 2011; Ma and Gundlach, 2015), feeding behavior (Ganella et al., 2013b), and a possible involvement in mental illnesses (Smith et al., 2014; Kumar et al., 2017) with a summary of associated relaxin-3 signaling via RXFP3 (Ma et al., 2017b; Olucha-Bordonau et al., 2018).