Abstract

Mitragyna speciosa Korth or ketum or kratom has long been used by local people in Thailand and Malaysia to treat various types of diseases and to boost energy. There is lack of information available on the effect of M. speciosa Korth in learning and memory function, therefore this study was conducted to understand its effect using a cellular model (hippocampus). The objective of this study was to delineate the effect of M. speciosa Korth standardized methanol extract (MS), we used extracellular recording in rat hippocampal slicesin vitro. Acute hippocampal slices were prepared from 4 weeks-old male Sprague dawley rats. Field excitatory post-synaptic potentials (fEPSP) were investigated after the application of test materials in concentrations of 0.0001, 0.001, 0.005, 0.01, 0.05 and 0.1% dissolved in 0.1% DMSO. The 50% inhibitory concentration (IC₅₀) of test material was then calculated. Superfusion of MS (all concentrations) produced irreversible fEPSP amplitude reduction with an IC₅₀ of 0.008%. The same concentration of MS (0.008%) prevented the induction of long-term potentiation (LTP) and induced only short-term potentiation (STP) in CA1 neurons. In the CA1 region of the hippocampus, reduced concentration-dependently glutamatergic transmission and blocked LTP at the IC_50.

Key words: Mitragyna speciosa Korth standardized methanol extraction (MS), extracellular recording, field excitatory post-synaptic potential (fEPSP), short-term potentiation (STP).