Electrophysiological actions of the plant alkaloid 6-benzoylheteratisine in rat hippocampal slices

The effects of the Aconitum alkaloid 6-benzoylheteratisine on neuronal activity was investigated in the in vitro slice preparation of rat hippocampus by extracellular recording of the stimulus-evoked population spike. 6-Benzoylheteratisine (0.01-10 μΜ) depressed the orthodromic and antidromic population spike in a concentration-dependent manner.The action of the drug was activity-dependent. The latency of onset of the inhibition was accelerated when the frequency of electrical stimulation had been increased. Furthermore, the effect of 6-benzoylheteratisine was evaluated in two different models of epileptiform activity induced either by blockade of GABA receptors by bicuculline (10 μΜ) or by a nominal Mg²⁺-free bathing medium. Due to the activity-dependent mode of action, this drug effectively reduced the number and the size of the synaptically evoked population spikes in the presence of bicuculline or nominal Mg²⁺-free bathing medium, respectively. Received: 23 September 1996 / Accepted: 2 January 1997