Ameliorative effects of olibanum essential oil on learning and memory in A beta 1-42-induced Alzheimer's disease mouse model

Purpose: To study the effect of olibanum essential oil (OEO) on learning and memory in Alzheimer's disease (AD) mouse. Methods: Mice were administered the 42-amino acid form of amyloid beta-peptide (A beta 1-42) to induce AD and then treated with OEO at 150, 300, and 600 mg/kg, p.o. for two weeks. Following treatment, the AD mice were assessed by step-down test (SDT), dark avoidance test (DAT), and Morris water maze test (MWM). Blood and brain tissues were collected for biochemical assessments. Gas chromatographymass spectroscopy was used to analyze the main constituents of OEO. Results: The main constituents of OEO were limonene, alpha-pinene, and 4-terpineol. Treatment with OEO prolonged t latency in SDT and DAT, but decreased error times. Escape latency decreased and crossing times were rose in the MWM following OEO treatment (p < 0.5). Treatment with OEO also enhanced the acetylcholine levels and decreased the acetylcholinesterase levels in serum and brain tissue (p < 0.5). Additionally, OEO reduced amyloid plaques in the hippocampus and protected hippocampal neurons from damage. Furthermore, OEO decreased c-fos expression in hippocampus tissues from AD mice (p < 0.5). Conclusion: OEO has significant ameliorative effect AD-induced deterioration in learning and memory in AD mouse induced by A beta 1-42. The mechanisms of these effects are related to increased acetylcholine contents, reduction of amyloid plaques, protection of hippocampal neurons, and down-regulation of c-fos in brain tissues. The results justify the need for further investigation of candidate drugs derived from OEO for the management of AD.