Nose-to-brain delivery of quercetin-loaded chitosan nanoparticles improves post-traumatic stress disorder-like...

Post-traumatic stress disorder (PTSD) is a stressful mental illness that arises after exposure to unforeseen traumatic events. The majority of PTSD cases are often refractory to pharmacological interventions. Herein, considering the neuroprotective effects of quercetin and chitosan in several brain disorders, we examined the effect of quercetin-loaded chitosan nanoparticles (QCNPs), administered via nose-to-brain delivery, on PTSD-like phenotypes in mice. QCNPs were synthesized using the ethanol injection method. We observed uniform spherical structure and 120-170 nm diameter of nanoparticles in transmission-electron microscopy analysis. The polydispersity index, zeta potential, and entrapment efficiency were 0.36 ± 0.0104, 39.05 mV, and 81.86 ± 1.60%, respectively. Male C57BL/6 mice subjected to controlled-cortical impact (CCI) surgery followed by single-prolonged stress (SPS) exhibited PTSD-like symptoms, including deficits in sociability, anxiety and cognition. The CCI+SPS-driven neurobehavioral dysfunctions related to sociability index, anxiety-like phenotype, and cognition were evaluated employing social-approach social avoidance (SASA), elevated zero maze (EZM), Y-maze, and novel object recognition task (NORT). Intranasal delivery of QCNPs, at 0.06 mg/kg of body weight for 14 days, ameliorated CCI+SPS-generated PTSD-like behaviors in mice. The depleted levels of postsynaptic-density protein 95 (PSD-95), brain-derived neurotrophic factor (BDNF), and doublecortin in the hippocampus of CCI+SPS-exposed mice were restored following QCNPs treatment. Moreover, QCNPs administration reduced the expression of astrocyte marker glial-fibrillary acidic protein (GFAP), IBA-1, c-Fos, and proinflammatory cytokines (C-reactive protein, IL-6, TNF-α, and IL-1β) in the hippocampus of CCI+SPS group. These results suggest that nose-to-brain delivery of QCNPs reverses CCI+SPS-generated PTSD-like phenotypes by modulating neuroinflammatory mediators and enhancing neuronal and synaptic proteins.