LEP and obesity due to melanocortin 4 receptor deficiency: Celastrol as a leptin sensitizer exhibited significant weight loss and food consumption reduction in HFD-obesity animals (Wang et al., 2014; Liu et al., 2015; Ma et al., 2015; Zhang et al., 2017a; Hu et al., 2017; Luo et al., 2017; Kyriakou et al., 2018; Pfuhlmann et al., 2018; Zhang et al., 2018; Feng et al., 2019a; Zhao et al., 2019a; Feng et al., 2019b; Chellappa et al., 2019; Fang et al., 2019; Saito et al., 2019; Abu Bakar et al., 2020; Hu et al., 2020; Zhu C. et al., 2021; Zhu Y. et al., 2021; Hua et al., 2021; Ouyang et al., 2021; Yang et al., 2021) (Table 1).