Sexual pheromone or conventional odors increase extracellular lactate without changing glucose utilization in specific brain areas of the rat.

Brain extracellular lactate levels increase following physiological stimuli. Monitoring lactate levels might be a tool for detecting dynamic changes in brain activity. In this study we compared changes of extracellular lactate in selected brain areas with rates of glucose utilization as measured by the [14C]2-deoxyglucose method, following olfactory stimulation. Conventional (green pepper essence, heptanal, exanal, octanal) and, above all, non-conventional (sexual pheromone) odors increased lactate in the rhinencephalum, but not in the striatum. Glucose utilization did not change in any area. This discrepancy may result from the different temporal resolution of the two methods employed and/or from the clearance of lactate, whose tissue content increases transiently following neuronal activation as a reflection of the initial oxygen debt.