Clove Oil Reverses Learning and Memory Deficits in Scopolamine-Treated Mice

The present study was performed to examine the effect of Eugenia caryophyllata (Myrtaceae) on learning and memory, and also evaluate whether it can modulate oxidative stress in mice. Passive avoidance step-down task and elevated plus-maze were used to assess learning and memory in scopolamine-treated mice. Oxidative stress parameters were also assessed in brain samples by estimating the malondialdehyde (MDA) and reduced glutathione (GSH) levels at the end of the study. Scopolamine (0.3 mg/kg, i.p.) produced impairment of acquisition memory as evidenced by a decrease in step-down latency and an increase in transfer latency on day 1, and also impairment of retention of memory on day 2. Pretreatment with clove oil (0.05 mL/kg and 0.1 mL/kg) for 3 weeks significantly reversed the increase in acquisition latency and all the doses (0.025, 0.05, 0.1 mL/kg, i.p.) reversed the increase in retention latency induced by scopolamine (0.3 mg/kg, i.p.) in elevated plus-maze. However, 0.05 mL/kg clove oil attenuated memory deficits in the passive avoidance step-down task. Brain samples showed a significant decrease in MDA levels in the group treated with clove oil (0.05 and 0.025 mL/kg). GSH levels were also increased in clove oil-treated mice though the results were not significant. Thus, it can be concluded that clove oil can reverse the short-term and long-term memory deficits induced by scopolamine (0.3 mg/kg, i.p.) and this effect can, to some extent, be attributed to decreased oxidative stress.