Local cerebral glucose utilization in septic rats

To identify cortical and subcortical structures in the brain which are associated with septic encephalopathy, local cerebral glucose utilization (LCGU) in the 31 discrete regions were evaluated with a quantitative (14C)-2.deoxyglucose autoradiographic method in the septic rat model. Sepsis was produced by cecal ligation and punctures. Forty rats were subjected to behavioral study and divided into two groups (control, n = 15; sepsis, n = 25). Septic rats died within 36 h, and the rats developed behavioral depression, and showed EEG slowing and an increase in pain threshold. The latter was evaluated by a tail flick method within 8 h after the surgical procedures, while control rats did not show significant change in either behaviors or pain threshold. In another study, LCGU was measured when behavioral depression, increase in pain threshold, and EEG slowing developed in the sepsis group (n = 7). In this group, the mean LCGU in auditory and parietal cortices, lateral geniculate, superior colliculus, hippocampus, and locus ceruleus was 95, 74, 67, 69, 72, and 53 mumol.100 g-1.min-1, being lower by 23%, 22%, 18%, 19%, 14%, and 27% than that in the sham-operated control group (n = 7), respectively. However, the mean LCGU in septal and raphe nuclei was 52 and 84 mumol.100 g-1.min-1, being significantly higher by 27% and 33% than that in the control group, respectively. These results suggest that septic encephalopathy is associated with metabolic changes in the discrete brain regions, which are related to the serotonergic or noradrenergic system.