Previous studies have shown results from the brain tissue of PTSD-like and non-PTSD-like rats found significantly lowered levels of β-endorphin in the amygdala of the PTSD-like group [43], although post-exercise plasma beta-endorphin levels have been found to be significantly higher than resting levels in the PTSD patients only, suggesting a more exaggerated response [43]. Here, POMC is linked to post-traumatic stress disorder.