title: Investigation of thymol effect on learning and memory impairment induced by intrahippocampal injection of amyloid beta peptide in high fat diet- fed rats.
abstract: Obesity and consumption of a high fat diet (HFD) are known to increase the risk of Alzheimer's disease (AD). In the present study, we have examined the protective and therapeutic effects of thymol (main monoterpene phenol found in thyme essential oil) on a HFD-fed rat model of AD. Fourty adult male Wistar rats were randomly assigned to 5 groups:(n = 8 rats/group): group 1, control, consumed an ordinary diet, group 2 consumed a HFD for 8 weeks, then received phosphate-buffered saline (PBS) via intrahippocampal (IHP) injection, group 3 consumed HFD for 8 weeks, then received beta-amyloid (Aβ)1-42 via IHP injections to induce AD, group 4 consumed HFD for 8 weeks, then received Aβ1-42, and was treated by thymol (30 mg/kg in sunflower oil) daily for 4 weeks, and group 5 consumed HFD for 8 week, then received Aβ1-42 after what sunflower oil was administered by oral gavage daily for 4 weeks. Biochemical tests showed an impaired lipid profile and higher glucose levels upon consumption of HFD, which was ameliorated by thymol treatment. In behavioral results, spatial memory in group 3 was significantly impaired, but groups treated with thymol showed better spatial memory compared to group 3 (p ≤ 0.01). In histological results, formation of Aβ plaque in hippocampus of group 3 increased significantly compared to group 1 and group 2 (p ≤ 0.05), but group 4 showed decreased Aβ plaques compared to group 3 (p ≤ 0.01). In conclusion, thymol decreased the effects of Aβ on memory and could be considered as neuroprotective.
authors.affiliation: Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Masoumeh
authors.initials: M
authors.lastname: Asadbegi
authors.affiliation: Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran. yaghmaei_p@srbiau.ac.ir.
authors.forename: Parichehreh
authors.initials: P
authors.lastname: Yaghmaei
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Iraj
authors.initials: I
authors.lastname: Salehi
authors.affiliation: Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Komaki
authors.affiliation: Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, 1411413137, Iran. aehabibi@sina.tums.ac.ir.|Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran. aehabibi@sina.tums.ac.ir.
authors.forename: Azadeh
authors.identifier: http://orcid.org/0000-0002-8993-4859
authors.initials: A
authors.lastname: Ebrahim-Habibi
mesh_terms: D016229:Amyloid beta-Peptides / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D000890:Anti-Infective Agents / Q000008:administration & dosage; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D059305:Diet, High-Fat / Q000009:adverse effects*; D006624:Hippocampus / Q000187:drug effects* / Q000473:pathology; D007276:Injections, Intraventricular; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced / Q000188:drug therapy* / Q000473:pathology; D010446:Peptide Fragments / Q000008:administration & dosage / Q000633:toxicity*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013943:Thymol / Q000008:administration & dosage*; D016896:Treatment Outcome
chemical_list: D016229:Amyloid beta-Peptides; D000890:Anti-Infective Agents; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42); D013943:Thymol
keywords: Abeta; Alzheimer's disease; High fat diet; Memory; Thymol