Effects of general anesthetics in hippocampus of SAM mice and establishment of the safety for Anesthesia in senile dementia

In order to investigate whether dementia modifies the anesthetic actions in the central nervous systems, we have studied effects of general anesthetics on the hippocampal synaptic transmission using the dementia model mice. Field population spikes of hippocampal CA1 pyramidal neurons were elicited in vitro using orthodromic stimulation of Schaffer collateral commissural fibers(test pulse). The recurrent inhibition was enhanced with the second stimulating electrode placed in alveus hippocampi(prepulse) to activate recurrent inhibition of CA1. The prepulses were applied as train stimuli to activate release and then depleteγ-amino-butyric acid(GABA) at presynaptic terminals of inhibitory interneurons. Sevoflurane and thiopental had greater actions on inhibitory synaptic transmission in dementia model mice than in control mice. The pre-pulse train protocol revealed that the anesthetic-induced GABA discharge was more enhanced in dementia mice than in control mice. Dementia enhances the actions of general anesthetics due to the increase in GABA release from presynaptic terminals.