Enhancement of lactate metabolism in the basolateral amygdala by physical and psychological stress: role of benzodiazepine receptors.

Lactate is considered to play a significant role in energy metabolism and reflect neural activity in the brain. Using in vivo microdialysis technique, we measured extracellular lactate concentrations in the basolateral amygdaloid nucleus (BLA) of rats under electric footshock or psychological stress. We also attempted to determine whether the stress-induced changes of extracellular lactate concentrations in the BLA are attenuated by diazepam, an agonist at benzodiazepine receptors, and whether FG7142, an inverse agonist at benzodiazepine receptors, have a facilitative effect on energy metabolism in the BLA. Both footshock and psychological stress led to an increase in extracellular lactate concentrations in the BLA. Similar increment of extracellular lactate levels was observed by administration of FG7142. Pretreatment with diazepam attenuated the ability of FG7142, as well as physical or psychological burden, to increase lactate levels in the BLA. These results indicate that a variety of stressors enhances energy metabolism in the BLA, and suggest that some stress-induced changes in energy metabolism are regulated by benzodiazepine receptors.