Selective metabolic activation of the hippocampus during lidocaine-induced pre-seizure activity.
Neurophysiologic studies indicate that local anesthetic-induced seizures are generated in subcortical brain structures. The authors utilized a quantitative autoradiographic technique to measure cerebral metabolism during lidocaine-induced seizure activity in rats anesthetized with nitrous oxide. Local cerebral metabolic rate for glucose (l-CMRg) was determined when lidocaine infusion resulted in sustained electroencephalographic patterns consisting of approximately 100--125-mu volt discharges with a frequency of about 9 Hz, lasting 1-2 sec, and superimposed upon almost isoelectric periods lasting 1-3 sec. Significant reductions in 1-CMRg (30-70 per cent decreases) occurred in 19 of 26 regions surveyed. All areas of cerebral cortex had decreased glucose uptake following lidocaine administration. The hippocampus developed a striking increase in 1-CMRg of 237 per cent, while the amygdala and other related nuclei sustained metabolic rates similar to those present before lidocaine was given. This study demonstrates a coupling of metabolic activity with functional activity in subcortical structures recognized to be involved in the generation of local anesthetic seizure activity. Additionally, it reveals a heterogeneous response of cerebral metabolism to lidocaine infusion in the presence of subcortically localized seizures.
D000818:Animals; D001345:Autoradiography; D001921:Brain / Q000378:metabolism; D002250:Carbon Radioisotopes; D003847:Deoxyglucose / Q000378:metabolism; D004569:Electroencephalography; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism*; D008012:Lidocaine; D008297:Male; D051381:Rats; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism*
D002250:Carbon Radioisotopes; D008012:Lidocaine; D003847:Deoxyglucose; D005947:Glucose