Background
It has been well documented that social isolation stress (SIS) can induce posttraumatic stress disorder (PTSD)-like behavior in rodents, however, the underlying mechanism is remained misunderstood. In the current study, we aimed to elucidate the role of NO/NMDAR pathway in PTSD-like behavior through modulating of astrocyte activity and improvement of oxidative stress.
Conclusion
Based on these results, it could be hypothesized that blockage of NO/NMDAR pathway might be a novel treatment for PTSD-like behavior in animals by inhibiting the astrocyte and regulating oxidative stress level.
Methods
Male NMRI mice were used to evaluate the memory function by using Morris water maze (MWM) and fear memory extinction by using freezing response. We used MK-801 (NMDAR-antagonist), L-NNA (NOS-inhibitor), NMDA (NMDAR-agonist), and L-arginine (NO-agent) to find a proper treatment. Also, immunohistochemistry, RT-PCR, and oxidative stress assays were used to evaluate the levels of astrocytes and oxidative stress. We used five mice in each experimental task.
Results
Our results revealed that SIS could induce learning and memory dysfunction as well as impairment of fear memory extinction in MWM and freezing response tests, respectively. Also, we observed that combined treatment including blockage of NOS (by L-NNA, 0.5 mg/kg) and NMDAR (by MK-801, 0.001 mg/kg) at subeffective doses could result in improvement of both memory and fear memory. In addition, we observed that SIS significantly increases the GFAP expression and astrocyte activity, which results in significant imbalance in oxidative stress. Coadministration of MK-801 and L-NNA at subeffective doses not only decreases the expression of GFAP, but also regulates the oxidative stress imbalance