Brain regional glucose use during Soman-induced seizures

The (14C)-2-deoxyglucose procedure was used to determine the effects of the potent acetylcholinesterase inhibitor Soman on regional metabolism in the brain. Groups of rats were given 112 micrograms/kg Soman, 84 micrograms/kg Soman, or saline i.m., and 15 min later the (14C)-2-deoxyglucose mapping procedure was initiated. All animals given 112 micrograms/kg Soman and 2 of 6 given 84 micrograms/kg Soman developed seizures that continued throughout the mapping procedure. Very high rates of glucose use occurred in most of the brain regions studied during seizures. The most striking increases occurred in substantia nigra, septum, outer layer of dentate gyrus of the hippocampus, hippocampal body, frontal cortex, caudate, ventral thalamus, parietal cortex, medial geniculate and interpeduncular nucleus. Only the inferior colliculus, superior olivary nucleus and lateral habenula were unaffected by the seizures. The mid layers of cerebral cortex rostral to superior colliculus showed marked reductions in glucose use which may represent inhibition of neuronal activity or functional failure from depleted energy reserves. The animals given 84 micrograms/kg i.m. that did not have seizures had regional glucose use patterns similar to the controls. The results indicate that the brain damage observed by others in Soman treated rats may be in part due to the excessive neuronal stimulation that occurs during the prolonged Soman-induced seizure.