Background: Chronic stress increases the production of pro-inflammatory cytokines and oxidative stress in the brain, which underlay cognitive and psychological problems. In addition to the anti-depressants, vitamin D is known to act as an anti-inflammatory and anti-oxidative agent. This study investigates the specific effects of vitamin D in protecting hippocampus and pre-frontal cortex (PFC) against chronic mild stress (CMS)-induced activation of pro-inflammatory cytokines IL-6 and TNF-α and decreasing the activation of anti-oxidative enzymes super oxide dismutase (SOD) and glutathione peroxidase (GPx).
Methods and results: Rats were exposed to CMS for 3 weeks. Two groups of rats received vitamin D (5 and 10 μg/kg) and another received fluoxetine (5 mg/kg) along with CMS. Control groups were not exposed to CMS, but received treatments similar to CMS groups. Serum corticosterone and IL-6, TNF-α and SOD and GPx levels in the hippocampus and PFC were measured at the end of three weeks. CMS significantly increased corticosterone, IL-6, TNF-α and decreased SOD and GPx levels (P < 0.0001) in hippocampus and PFC. Vitamin D treatment reduced corticosterone levels (P < 0.01), increased SOD (P < 0.0001) and GPx (P < 0.01) and decreased IL-6 and TNF-α (P < 0.0001) levels in the hippocampus and PFC compared to rats treated with vitamin D vehicle. Vitamin D-10 regulation of SOD and IL-6 levels was more effective than fluoxetine (P < 0.0001 and P < 0.01, respectively, in hippocampus).
Conclusion: This study suggests that vitamin D effectively protects the key regions of the brain related to cognition and affective behavior, against the inflammation and oxidative stress caused by the chronic stress.
Keywords: Anti-oxidative enzymes hippocampus; Chronic mild stress (CMS); Pre-frontal cortex (PFC); Pro-inflammatory cytokines; Vitamin D.
© 2021. The Author(s), under exclusive licence to Springer Nature B.V.