The enhancing effect of Aubang Gahl Soo on the hippocampal synaptic plasticity and memory through enhancing cholinergic system in mice

Ethnopharmacological relevance: Aubang Gahl Soo (AGS) is a Korean traditional drink manufactured from medicinal plants and fruits using sugar or honey. Although traditional old book stated its effects on body, there is no scientific evidence yet. Therefore, in the present study, we tested AGS on brain functions. Aim of this study: In this study, we tried to uncover the effect of on brain functions. To do this we examined the action of AGS on the hippocampal synaptic function and memory in mice. Materials and methods: To examine the effect of AGS on synaptic plasticity, we observed input-output curves (I/O curve), paired-pulse facilitation (PPF), and long-term potentiation (LTP) using mouse hippocampal slices. Moreover, to investigate the functional relevance of the effect of AGS on synaptic plasticity, we conducted passive avoidance, Y-maze and Morris water maze tests. To examine relevant mechanism, acetylcholinesterase (AChE) activity and acetylcholine (ACh) level assay were also conducted. Results: In the basal synaptic transmission study, we found that AGS did not affect I/O curves and PPF. However, AGS facilitated hippocampal LTP in a concentration-dependent manner. Moreover, AGS blocked AChE activity (IC₅₀ = 485 μg/ml). Moreover, ACh level was increased by AGS (100 μg/ml) treatment. Along with this, facilitating effect of AGS on hippocampal LTP also blocked by scopolamine, a muscarinic acetylcholine receptor antagonist. Moreover, AGS also ameliorated memory impairments induced by scopolamine in passive avoidance, Y-maze, and Morris water maze tests. Conclusions: These results suggest that AGS facilitates hippocampal LTP through activating cholinergic system and ameliorates cholinergic dysfunction-induced memory deficit.