ناهید مجلسی

Recent studies have shown Cinnamomum zeylanicum antioxidant/anti-inflammatory activities, and inhibition of tau accumulation and Amyloid beta (Aβ)   aggregation. Therefore, it seems that this plant can improve cognition in rat model of Alzheimer’s disease (AD). For this purpose, the ability of an aqueous extract of cinnamon in attenuating Aβ-induced learning impairment was evaluated in a rat model of AD.

Aβ-protein fragment 25-35 was injected into the CA1 region of rats’ hippocampus and the effect of different doses of cinnamon extract (5, 10, or 20 mg/kg) on cognitive function was assessed in the Morris water maze. Animals were subjected to 5 days of training; 4 days with the invisible platform to test spatial learning and the 5th day with the visible platform to test motivation and sensorimotor coordination.

The results showed an significant increase in escape latency, traveled distance, orientation angle and decrease in target quadrant entries in Aβ-received rats. Cinnamon extract was able to significantly reduce the effect of Aβ.

The results indicates learning and memory impairment in Aβ25-35 groups. These impairments were reversed by administration of Cinnamomum zeylanicum extract. Our results suggest that cinnamon may be a valuable agent for alleviating symptoms of Aβ.

Alzheimer's disease (AD) is the most common age-associated neurodegenerative disease with involvement of genetic factors. Recent studies have shown that the protein cystatin C binds soluble Aβ and inhibits Aβ oligomerization and amyloidogenesis, protecting the brain against amyloid-induced toxicity. Moreover, a decreased cystatin C secretion is associated with a polymorphism found in the cystatin C gene. In this study the association between rs1064039 polymorphism and late-onset AD was investigated.

We conducted a case-control study including a clinically well-defined group of 160 late-onset AD patients and 167 age-matched controls. The polymorphism was determined by polymerase chain reaction-restriction fragment length polymorphisms (PCR-PFLP) assay. The allele frequency was analyzed by Chi-square test.

In the group of patients, the frequency of G/G homozygotes was lower, and the frequency of G/A genotype was higher than the corresponding control group (p <0.05).

The results obtained from our study demonstrate an association between rs1064039 polymorphism in CST3 gene and late-onset AD in an Iranian population. Given the minimal significance level of the G/A genotype, this polymorphism seems to have minor effects on the progression of Alzheimer's disease or possibly interfere with other risk factors.
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In the previous study, the effects of Zataria multiflora (ZM) and its main constituents carvacrol and thymol were evaluated and it was found that they could alleviate cognitive impairments caused by amyloid β (Aβ) in rodent model of Alzheimer’s disease. In this study, the effect of ZM against Aβ25-35-induced cytotoxicity and reactive oxygen species (ROS) accumulation in PC12 cells as a model of Alzheimer's disease was evaluated.

First, PC12 cells were exposed to Aβ25-35 and different concentrations of ZM for 48 h. Then, the cell viability was determined by methyl thiazolyl tetrazolium (MTT) method. Fluorospectrometer was employed to observe ROS production.

The results indicated that concentrations of 18.75, 37.5 and 75 μl/L of ZM could significantly rescue and protect PC12 cells against Aβ25-35-induced cytotoxicity (p< 0.001). Furthermore, the data demonstrate that Aβ25-35 induced intracellular ROS, while the concentrations of 18.75 (p <0.05), 37.5 and 75 (p <0.001) µL of ZM could significantly reverse Aβ25-35 induction of ROS generation.

According to these findings, ZM could attenuate the level of intracellular ROS induced by Aβ. Therefore, ZM could have antioxidant activity. Ability of ZM to reduce ROS and its protective effects against Aβ-induced cellular damage in PC12 cells may indicate its potential for treatment of Alzheimer’s disease. Further studies are required to determine its clinical efficacy.