Basic mechanisms of penicillin-induced epileptiform discharges.
A short survey is given of recent studies on epileptogenesis, concentrating on data obtained by adding penicillin to hippocampal slices in vitro. Epileptiform burst discharges, similar to the interictal responses of intact preparations, are elicited by synaptic activation. Neither the afferent fibres nor the synaptic transmission per se are changed. Excitatory synaptic potentials are, however, prolonged due to abolition of gamma-aminobutyric acid (GABA)-mediated inhibitory processes. The consequent increased membrane resistance allows the synaptic depolarization to trigger slow depolarizing waves, most likely in the dendrites. A possible explanation is that these waves are due to inward calcium currents, generated when the cell is in a special condition which facilitates such currents. The facilitatory factors are discussed.
D000200:Action Potentials; D000818:Animals; D001696:Biomechanical Phenomena; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009412:Nerve Fibers / Q000502:physiology; D009433:Neural Inhibition; D010406:Penicillins; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*; D013569:Synapses / Q000502:physiology
D010406:Penicillins