The effects of aqueous extract of Origanum vulgare on learning and memory in male rats

Introduction: The effectiveness of antioxidants on learning and memory improvement has been shown, previously. Due to the high level of antioxidants, available in Origanum vulgare, the present experiment aimed to examine the effect of aqueous extract of O. vulgare on passive avoidance learning (PAL) in male Wistar rats. Methods: This study was performed on ۳۰ male Wistar rats weighing ۲۵۰ to ۲۹۰ g. The rats were randomly assigned into five groups (n=۶), as follows: the control, sham (saline), and three groups treated with different doses of O. vulgare extract (۱۵۰, ۲۵۰, and ۳۵۰ mg/kg). The saline or extract was administered via daily oral gavage for ۱۴ days. The groups were then subjected to the passive avoidance task, and their behaviors were recorded. The rats’ locomotor activity was also measured using the open field test. Results: The number of trials to acquisition was significantly lower in the "O. vulgare (۳۵۰ mg/ kg)" group than the control group. The step-through latency and the time spent in the dark compartment in the retention test, was significantly higher and lower in the "O. vulgare (۲۵۰ and ۳۵۰ mg/kg)" groups than the control group, respectively. No significant differences were found in the distances traveled among the experimental groups in the open field test. Conclusion: Aqueous extract of O. vulgare can enhance learning and memory. The high levels of antioxidants in O. vulgare extract may be responsible for its effectiveness in learning and memory.