Cerebral blood flow and metabolism in soman-induced convulsions

Abstract

Regional cerebral blood flow (CBF) and regional cerebral glucose utilization (CGU) were studied by quantitative autoradiographic techniques in rats. Animals were treated either with a toxic dose of soman, an irreversible organophosphorus cholinesterase inhibitor, that produced convulsions or with saline as controls. An increased arterial blood pressure (mean increase = 41% of control) always preceded onset of convulsions. Convulsive activity was associated with an increase of plasma glucose concentration and marked increases over controls of CGU [average of all regions: control = 75 ± 5 μmol · 100 g −1 · min −1, n = regions/ animals (304/8); seizures = 451 ± 20 μmol · 100 g −1 · min −1, n = 190/5] and CBF [average of all regions: control = 135 ± 6 ml · 100 g −1· min −1, n= 190/5; seizures = 619 ± 29 ml · 100 g −1 · min −1, n = 190/5). Regional distribution of these effects revealed a greater proportional increase of CBF over CGU in cingulate, motor and occipital cortex and caudateputamen. In contrast, a lower proportional increase of CBF over CGU in CA3 region of hippocampus, dentate gyrus, medial thalamus and substantia nigra was observed, implying the existence of a relative ischemia in these brain areas. These findings may be relevant to the pathogenesis of brain lesions associated with soman-induced convulsions.