The effect of hydroalcoholic extract of Ziziphora clinopodioides L. on spatial memory and neuronal density of hippocampal CA1 region in rats with sporadic Alzheimer's disease

OBJECTIVE: Alzheimer's disease is a neurodegenerative disorder associated with gradual loss of cognitive and memory abilities. It was shown that the hippocampus is one of the first structures in the brain that is affected by the disease. Ziziphora clinopodioides (Z. clinopodioides) is a member of Lamiaceae family and contains various substances. MATERIALS AND METHODS: In this experimental study, 72 adult male Wistar rats were used for behavioral and histopathologic studies. They were divided into nine groups included: control, negative control (Alzheimer), positive control (Alzheimer's treated with rivastigmine), aCSF (artificial cerebrospinal fluid) + ziziphora extract with doses of 200,400, and 600 mg/kg, and STZ (stereptozotocine)+ziziphora extract in 200,400,600 mg/kg doses. The injury was created with bilaterally intraventricular injection. The spatial memory was studied by passive avoidance test and neuronal density was evaluated by dissector method. To examine the histopathological lesions, Congo red and toluidine blue staining were done. Data were analyzed by ANOVA Minitab software. RESULTS: The memory index (neuronal density and passive avoidance test results) showed a significant decrease in negative control group compared to control (p≤0.001). Treatment with the hydroalcoholic extract at the doses of 400 and 600 mg/kg showed a significant increase in memory index in rats with Alzheimer's disease (p≤0.001). The effect of 200 mg/kg extract was not significantly different from that of the negative control group. The results of histological analysis indicated beta-amyloid plaques formation in the control group as compared to the negative control group while treatment with the extract at the doses of 400 and 600 mg/kg, significantly reduced beta-amyloid plaques formation. CONCLUSION: These findings suggest that the extract of Z. clinopodioides can improve Alzheimer's condition and alleviate memory and histopathologic damages; also, it decreases beta-amyloid plaques and apoptosis in CA1 region of the hippocampus.