Carvacrol suppresses learning and memory dysfunction and hippocampal damages caused by chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion (CCH) is a common phenomenon in many neurological diseases such as vascular dementia and Alzheimer's disease. Several drugs have been investigated to prevent and treat the CCH. The carvacrol (CAR) has been shown to have beneficial effects on various neurodegenerative and neuropsychiatric disorders. Accordingly, the present study was designed to evaluate the effect of CAR on neuronal damages in hippocampus in a well-defined model for CCH. Forty-eight male Wistar rats were equally divided into four groups of sham (A), CCH (B), CCH+ CAR 25, and 50 mg/kg/daily (C and D). The animals were subjected to permanent bilateral occlusion of the carotid arteries (2-vessel occlusion, 2VO) to induce CCH model. Cognitive function was evaluated by Morris water maze test. Morphological changes of hippocampus were assessed using Nissl staining. Free radical scavenging activity was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. Moreover, catalase (CAT) and superoxide dismutase (SOD) activities and lipid peroxidation levels were measured using biochemical analysis. CAR significantly improved the spatial learning and memory deficits assessed using the Morris water maze test. CAR also significantly attenuated neuronal necrosis as well as malondialdehyde (MDA) and elevated the levels of SOD and CAT activity in the hippocampus. The results indicate that CAR produces significant neuroprotective effects on neuronal damages induced by CCH. Protective effect of CAR may be mediated by antioxidative effect of this drug.