CCK and type 2 diabetes mellitus: In this study, the densities of CCK positive neurons were not associated with pathological values of type 2 diabetes in OLETF rats; however, Sherrin et al. reported that region-specific increases in CCK mRNA levels in emotion-related brain regions are induced by repeated administrations of cortagine (a corticotropin-releasing factor receptor 1-selective agonist) [48].