“…This stratification of MDD patients by HPA axis function suggests that different genetic predispositions may be underlying the divergent endophenotypes ( Antonijevic, 2006 ; Heinzmann et al, 2014 ). The stress reactivity (SR) mouse model is a genetic animal model, which recapitulates several of the key endophenotypes of the two MDD subtypes described above ( Touma et al, 2008 ; Heinzmann et al, 2014 ), including associated changes in bodyweight ( Touma et al, 2009 ), sleep architecture ( Touma et al, 2009 ; Fenzl et al, 2011 ), stress hormone profiles ( Touma et al, 2008 , 2009 ; Heinzmann et al, 2014 ), and cognitive performance ( Knapman et al, 2010a , b , 2012 ). Using this animal model, our group recently showed that an inherited predisposition for extremes in stress reactivity (high or low) interacts with ELS to shape short-term, as well as lasting consequences at the level of stress-coping behavior, neuroendocrine function, and gene expression ( McIlwrick et al, 2016 ).…”