Supplementation of Carvacrol Attenuates Hippocampal Tumor Necrosis Factor‐Alpha Level, Oxidative Stress, and Learning and Memory Dysfunction in Lipopolysaccharide‐Exposed Rats

Background: Carvacrol is a natural phenolic monoterpene with anti‐inflammatory and antioxidant bioactivities. Neuroinflammatory and oxidative stress responses play a crucial role in the pathogenesis of Alzheimer’s disease. The present study examined the effect of carvacrol on brain tumor necrosis factor‐alpha (TNF-α) level and oxidative stress as well as spatial learning and memory performances in lipopolysaccharide (LPS)‐exposed rats. Materials and Methods: The rats were treated with either carvacrol (25 and 50 mg/kg) or Tween 80 for 2 weeks. Thereafter, LPS (1 mg/kg) or saline was intraperitoneally administered on days 15–19, 2 h before Morris water maze task, and treatments with carvacrol or Tween 80 were performed 30 min prior to behavioral testing. The level of TNF‐α, lipid peroxidation, and total thiol concentration were measured in the hippocampus and cerebral cortex at the end of the experiment. Results: It was found that LPS‐exposed rats exhibited spatial learning and memory dysfunction, which was accompanied by increased TNF-α level and lipid peroxidation, and decreased total thiol concentration in the hippocampus and/or cortex. Moreover, treatment with carvacrol at a dose of 25 mg/kg attenuated learning and memory impairments, decreased TNF-α and lipid peroxidation level in the hippocampus and cortex, and increased total thiol concentration in the cortex. Conclusion: Carvacrol exerts neuroprotective effects against LPS‐induced spatial memory deficits through attenuating hippocampal TNF‐α level and oxidative stress in rats.