Brain Activation and Multiparametric Responses in Gerbils

Brain activation could be obtained by three techniques that were used frequently in the rat or cat models. The use of the Mongolian gerbil as an animal model in cortical spreading depression (CSD) studies was performed mostly or only by our research team. In this chapter, I summarize all of our results obtained after using various multiparametric monitoring systems in gerbils exposed to CSD in normoxia as well as under various pathophysiological conditions. In order to study the interrelation between the energy state of the brain and ionic homeostasis in vivo, we used the multiparametric monitoring approach developed by us a few years ago. The energy state was evaluated by monitoring the intramitochondrial redox state using the surface NADH fluorometry reflectometry. Relative cerebral blood flow (CBF) was measured by a laser Doppler flowmeter. Extracellular K+ and Ca2+ levels were monitored by mini-electrodes surrounded by DC steady potential electrodes. Spontaneous electrocortical activity (ECoG) was measured using bipolar electrodes. We exposed gerbils to the responses to CSD in the normoxic brain as well as after exposing the gerbil to ischemia, hypoxia, and deep anesthesia. It was found that the ability of the brain to recover from the CSD wave is dependent upon the availability of oxygen in the brain, which is a critical factor enabling the maintenance of ionic homeostasis in the brain tissue.