Eclipta prostrata L. (Asteraceae) has been prescribed for whole body nourishment and nervine tonic in Asia. However, the effects of
E. prostrata in learning and memory have not been fully explored.
Aim of the study
To scientifically elucidate the effects of E. prostrata on cognitive functions, we examined whether E. prostrata could ameliorate a cholinergic blockade-induced memory impairment, and we also investigated the effects of E. prostrata on the synaptic plasticity in the hippocampus.
Materials and methods
Memory impairment was induced by scopolamine, a cholinergic muscarinic receptor antagonist. The anti-amnesic effects of the ethanolic extract of Eclipta prostrata L. (EEEP) were measured in mice by the passive avoidance, Y-maze and Morris water maze tasks. To test the effects of EEEP on synaptic plasticity, we measured long-term potentiation (LTP) in the hippocampus. We also studied several signaling molecules related to learning and memory, such as phosphorylated protein kinase B (Akt) or phosphorylated glycogen synthase kinase-3β (GSK-3β).
Results
In the passive avoidance task, EEEP (50 or 100 mg/kg, p.o.) significantly ameliorated the shortened step-through latency induced by scopolamine. EEEP (100 mg/kg, p.o.) also showed significant increase in alternation behavior during the Y-maze task. In the Morris water maze task, scopolamine-induced a decrease in both the swimming time within the target zone and the number of crossings where the platform had been placed were significantly reversed by EEEP (50 or 100 mg/kg, p.o.). Moreover, EEEP (100 μg/ml) significantly enhanced hippocampal LTP without affecting basal synaptic transmission. The administration of EEEP (100 mg/kg) increased the phosphorylation levels of Akt and GSK-3β in the hippocampal region.
Conclusion
These results suggest that EEEP has memory-ameliorating activity against scopolamine-induced cognitive impairment and facilitates LTP in the hippocampus. This could be, at least in part, mediated by the activation of the Akt-GSK-3β signaling pathway.
