MLN and obesity due to melanocortin 4 receptor deficiency: Suncus murinus has been used in various fields of science due to its unique characteristics, which are distinct from laboratory rodents, including as models of emesis (Ebukuro et al., 2000), in vivo motilin studies (Tsutsui et al., 2009), and as a natural obesity-resistant animal model in recent studies (Yi et al., 2010; Zhang et al., 2020); however, the mechanism of natural obesity resistance is still not well understood.