ABSTRACT
ETHNOPHARMACOLOGICAL RELEVANCE: Dracocephalum moldavica (Moldavian balm) has been traditionally used for the treatment of intellectual disabilities, migraines and cardiovascular problems in East Asia. Recent scientific studies have demonstrated the usefulness of this plant to treat neurodegenerative disorders, including Alzheimer's disease. AIM OF THE STUDY: This study aimed to investigate the effects of the ethanolic extract of D. moldavica leaves (EEDM) on scopolamine-induced cognitive impairment in mice and the underlying mechanisms of action. MATERIALS AND METHODS: The behavioral effects of EEDM were examined using the step-through passive avoidance and Morris water maze tasks. To elucidate the underlying mechanism, we tested whether EEDM affects acetylcholinesterase activity and the expression of memory-related signaling molecules including extracellular signal-regulated kinase (ERK) and cAMP response element-binding protein (CREB) in the hippocampus. RESULTS: EEDM (25, 50 or 100 mg/kg) significantly ameliorated the scopolamine-induced step-through latency reduction in the passive avoidance task in mice. In the Morris water maze task, EEDM (50 mg/kg) significantly attenuated scopolamine-induced memory impairment. Furthermore, the administration of EEDM increased the phosphorylation levels of ERK and CREB in the hippocampus but did not alter acetylcholinesterase activity. CONCLUSIONS: These findings suggest that EEDM significantly attenuates scopolamine-induced memory impairment in mice and may be a promising therapeutic agent for improving memory impairment.
Subject(s)
Cognitive Dysfunction/drug therapy , Lamiaceae , Neuroprotective Agents/therapeutic use , Plant Extracts/therapeutic use , Acetylcholinesterase/metabolism , Animals , Avoidance Learning/drug effects , Behavior, Animal/drug effects , Cognitive Dysfunction/chemically induced , Cognitive Dysfunction/metabolism , Cyclic AMP Response Element-Binding Protein/metabolism , Extracellular Signal-Regulated MAP Kinases/metabolism , Hippocampus/drug effects , Hippocampus/metabolism , Male , Maze Learning/drug effects , Mice, Inbred ICR , Neuroprotective Agents/pharmacology , Phosphorylation/drug effects , Plant Extracts/pharmacology , Plant Leaves , Scopolamine , Signal Transduction/drug effectsABSTRACT
Alzheimer's disease (AD) is an important chronic neurodegenerative disorder and is mainly associated with cognitive dysfunction. At present, bioactive compounds from traditional medicinal plants have received much attention for the enhancement of cognitive function. Danshensu, a phenolic acid isolated from herbal medicines, has various pharmacological activities in the central nervous system, including anxiolytic-like and neuroprotective properties. The present study aimed to investigate the ameliorating effects of danshensu on scopolamine- and amyloid-ß (Aß) protein-induced cognitive impairments in mice. Danshensu (3 and 10â¯mg/kg, p.o.) effectively ameliorated scopolamine-induced cognitive dysfunction in mice, as measured in passive avoidance and Y-maze tasks. In a mechanistic study, danshensu inhibited monoamine oxidase A (MAO-A) activity but not MAO-B. Additionally, danshensu treatment increased the dopamine level and the phosphorylation levels of protein kinase A (PKA) and cAMP response element binding protein (CREB), in the cortex of the brain. Furthermore, the ameliorating effect of danshensu against scopolamine-induced cognitive impairment was fully blocked by H89, a PKA inhibitor. Finally, danshensu also ameliorated Aß-induced cognitive impairments in an animal model of AD. The results revealed that danshensu treatment significantly improved scopolamine and Aß-induced cognitive impairments in mice by facilitation of dopamine signaling cascade such as PKA and CREB due to MAO-A inhibition. Thus, danshensu could be used as a promising therapeutic agent for preventing and treating AD.
