Investigations in experimental animals are also beginning to unravel the role of FKBP5 in the neurobiology of depression and PTSD: Along with dysregulation of the HPA axis, SPS has been shown to acutely induce FKBP5 mRNA in prefrontal cortex, hippocampus and amygdala in rats 89. The gene discussed is FKBP5; the disease is major depressive disorder.