Figure 1.
Predator exposure/psychosocial stress regimen.
The predator exposure/psychosocial stress model includes two cat exposures over a 31-day period, combined with daily cage cohort changes. In addition, blood was collected at three different time points and ROS levels were measured to determine oxidative stress within groups and between groups. Anxiety was measured at the end of the stress regimen via EPM.
Table 1.
Rat primers used for real-time RT-PCR.
Table 2.
Growth rate and organ weights.
Figure 2.
Post-stress corticosterone levels.
After 31 days of the predator exposure/psychosocial stress regimen, plasma corticosterone levels were higher in the PTSD group. Corticosterone was measured in plasma collected at the time of sacrifice and frozen prior to testing. Data are presented as ± SEM. *p<0.05 relative to the control group.
Figure 3.
Elevated plus-maze performance.
The PTSD group displayed significantly higher anxiety than the control group, as evidenced by their reluctance to spend time in the open arms of the EPM (A). Total ambulations, however, were essentially equal between the two groups (B). Anxiety on the EPM was tested within 24 hours of the final day of the 31-day stress regimen. Data are presented as mean ± SEM. ***p<0.0001 relative to the control group.
Figure 4.
Reactive oxygen species in the brain and adrenal glands.
Superoxide, peroxynitrite, and total ROS were all significantly elevated in the hippocampus (A) and adrenal glands (C) in the PTSD group. Superoxide and total ROS were also elevated in the pre-frontal cortex (B) in the PTSD group, but peroxynitrite did not reach significance. All data are presented as mean ± SEM. *p<0.05, **p<0.001, ***p<0.0001 relative to the control group.
Figure 5.
Reactive oxygen species in the blood.
Superoxide (A) and total ROS (B) in the blood were measured between groups and within groups at three time points during the predator exposure/psychosocial stress regimen. Superoxide and total ROS were at approximately the same level for the PTSD and control groups at the beginning of the experiment, but progressively rose during stress. All data are presented as mean ± SEM. *p<0.05, ***p<0.0001 relative to the control group. ##p<0.001, ###p<0.0001 relative to the previous measurement of the same group.
Figure 6.
RT-PCR revealed IL-1β and NALP3 mRNA were significantly elevated in the hippocampus (A), PFC (B), and amygdala (C) in the PTSD group. All data presented as mean ± SEM. *p<0.05 relative to the control group.
Figure 7.
Western blot on the hippocampus (A &B) and PFC (C & D) tissue.
Western Blot showed IL-1β and NALP3 protein in the hippocampus (A & B respectively) and PFC (C & D respectively) were significantly elevated in the PTSD group. All data presented as mean ± SEM. *p<0.05 relative to the control group.
Figure 8.
Reactive oxygen species cause tissue damage and necrosis.
Cytokine production in PTSD leads to upregulation of superoxide and nitric oxide, which bind to form the very potent oxidizer peroxynitrite. The resulting tissue damage sustains the positive feedback loop causing further detrimental effects.