Author(s): Nasir M.N., Habsah M., Zulkifli, M. , Zamzuri, I.., Rammes, G., Hasnan, J., Abdullah, J.
An in vitro excitatory post-synaptic potential stimulation technique was used to examine the effects of asiatic acid (a. acid), an isolated compound of Centella asiatica on excitatory post-synaptic potential (EPSP) in the rat hippocampal slices. Hippocampal slices 350 μrn thick were perfused with oxygenated artificial cerebrospinal fluid, and electrodes were placed in the cornu ammonis (CA1) region to record EPSP responses to stimulation of Schaffer collat-eral/commissural fibers. Gamma-aminobutyric acid (GABA) receptors properties were measured with or without a. acid and all exposure to known GABA A or GABA B channel blockers; bicuculine or phaclofen. The major effect of a. acid was a dose and time dependent increase in the intensity and duration of GABA A blocker mediated inhibition compared with GABA B blocker, which was no response. Furthermore, the inhibitory concentration (IC50) value for a.acid was measured 14 μM. This depressant effect was not reversible after a 30-min washout of the a. acid and these experiments confirmed that a. acid having a selective GABA B receptor not for GABA A receptor.