Figure 4.

Animal studies show that capsaicin exerts both anti- and proepileptic effects. (A)—the top panel shows a schematic drawing of voltage-gated sodium channels in the plasma membrane of a brain cortical neuron. Example epileptic events recorded from a cortical neuron in vitro are also shown. A patch-clamp recording was made in proepileptic extracellular solution containing zero magnesium and potassium channels inhibitor 4-AP. The bottom panel shows that capsaicin potently inhibits epileptic activity [3]. The blockading of sodium channels by capsaicin removes depolarization and contributes to the antiepileptic effect of capsaicin. Please note that a number of other channels contribute to the generation of epileptic seizures such as calcium channels which may also be blocked by capsaicin. The recordings shown in Figure 4A were presented in our previous publication [3]. (B)—schematic drawing showing that capsaicin exerts proepileptic effects by the opening of calcium-permeable TRPV1 receptor/channels in hippocampal neurons [53,55]. Some of these channels are newly expressed under epileptic conditions. Calcium inflow causes depolarization of the membrane potential and exerts a proepileptic effect. If this process occurs in presynaptic axons, glutamate release is enhanced which may evoke seizures.