Neuroprotective Effect of Zataria Multiflora Essential Oil on Rats With Alzheimer Disease: A Mechanistic Study

Introduction: Finding herbs with promising effects to prevent or postpone Alzheimer Disease (AD) is highly demanded. The present study aimed at clarifying plausible effects and related mechanism(s) of Zataria Multiflora Essential Oil (ZMEO) against memory impairment in a rat model of the AD. Methods: Forty male adult rats were categorized into four groups and treated as follows: 1. The Negative Control (NC): no treatment; 2. Sham control (sham): distilled water by Intracerebroventricular (ICV) injection; 3. The AD control (AD): Aβ 1-42 by ICV injection; and 4. The ZMEO group: Aβ 1-42 by ICV injection and ZMEO at 100 μL/kg/d orally for 20 days.  Results: After Congo red staining of the hippocampus, a relative decrease in amyloid deposits was observed in the ZMEO group. Moreover, rats showed better outcomes in Morris Water Maze (MWM) test, reduced hippocampal acetylcholinesterase (AchE) activity, and higher Brain-Derived Neurotrophic Factor (BDNF) content as compared with the AD group (P<0.05). However, no significant changes in antioxidant status was observed (P>0.05). Conclusion: ZMEO has a protective effect against memory impairment in rats with AD at least partly via reducing hippocampal AchE activity and enhancement of BDNF levels without a change in antioxidant status. These findings can pave the way for future studies on the usefulness of this herb in AD prevention.