Introduction: The glutamatergic system plays an important role in learning and memory. Administration of crocus sativus (Saffron) or its constituent, crocin, facilitates the formation of memory. This research investigated the effect of crocin on antagonizing retrograde amnesia induced by ketamine, a glutamatergic receptor antagonist, in rats by shuttle box.Methods: Male Wistar rats were tested to measure their learning behavior in the passive avoidance task. All animals were trained by a 1 mA shock. The drugs were injected immediately after the training was successfully performed. The animals were tested 24h after training to measure Step Through Latency (STL).Results: On the test day, administration of ketamine (12 mg/kg, ip) impaired the memory after training. Different doses of crocin (2, 5 or 10 mg/kg, ip) were injected 30 min after ketamine, but only 2 mg/kg crocin could improve retrograde amnesia and 5 and 10 mg/kg doses did not have any significant effect on retrograde amnesia. Moreover, administration of crocin (2, 5 or 10 mg/kg, ip) after training had no significant impact on passive avoidance memory by itself.Conclusion: Considering the therapeutic effect of post-training administration of crocin on ketamine-induced retrograde amnesia, it can be argued that crocin has an interaction with glutamatergic system in formation of passive avoidance memory in rats.

Background: A Brief interruption of blood supply to the brain can cause significant changes in the function of central nervous system. Patients usually show cognitive, emotional and electrophysiological changes during recovery from stroke. Preliminary pharmacokinetic studies have shown that Thymus vulgaris is useful in the treatment of seizures, respiratory diseases, smooth muscular spasm and bloating.Methods: In an experimental study, for inducing temporary acute ischemia carotid artery was closed for 60 minutes and then blood flowwas restored. Thyme extract (50, 100 and 200 mg/kg) was injected daily after induction of ischemia. Shuttle box test was carried out for the first 4 days and rotarod test was conducted at the last day. After the rotarod test, blood samples were collected from heart and brain tissue was removed under deep anesthesia. One way-ANOVA followed by Tukey and t-paired tests were used for comparing the groups at 0.05 level of significance. All data were analyzed by using the statistical package for social sciences (SPSS-19) software.Results: In passive avoidance test, the initial latency time was significantly longer in the ischemia group compared to the control group. Administration of thyme extract into ischemic rats significantly increased second latency time and reduced MDA levels of brain cortex.Conclusions: Our results indicated that Thymus vulgaris extract has a neuroprotective activity. Mechanisms of neuroprotective action might be associated with antioxidant activity and inhibition of oxidative stress in rat brain.

Objective: Elevated amino acid homocysteine (Hcy) levels and insufficient physical activity are the risk factors in Alzheimer disease (AD) development. The effect of intermittent aerobic training on memory retention test and Thiobarbituric Acid Reactive Substances (TBARS) and superoxide dismutase (SOD) levels in the dorsal hippocampus of rats which were stimulated with Hcy is investigated.Methods: In order to determine the dose at which using Shuttle Box Test recognizes degenerative changes and/or memory impairment, 40 rats were injected by different dosages of Hcy to the dorsal hippocampus. It was observed that the required Hcy dose is 0.6 M. Then 44 rats were divided into four groups including training and control groups at 4 weeks of aerobic exercise in training and control groups at 8 weeks. To determine the effect of homocysteine on the memory impairment, Shuttle Box Test was used on treadmill (5 sessions/week, 12-18 m/min and 10-58.5 min).Results: Hcy administration caused memory impairment and significant increase in TBARS. Significant decrease in TBARS level was noted after 8 weeks of aerobic exercise, but not after just 4 weeks of exercise compared with control group. In addition, performing 8 weeks of aerobic training led to significantly increased superoxide dismutase (SOD) level and the time of avoidance learning test.Conclusion: Hyperhomocysteinemia caused learning and memory deficits probably by generating reactive oxygen species (ROS) and the present study showed that regular moderate intensity intermittent exercise may reverse this process and exercise is recommended as a strategy to improve symptoms of senile neurodegenerative disease.