Effect of anterior nucleus of thalamus stimulation on glucose metabolism in hippocampus of epileptic rats

Background  Electrical stimulation of the anterior nucleus of the thalamus (ANT) appears to be effective against seizures. In this study, we investigated changes in glucose metabolism during high-frequency stimulation of ANT in epileptic rats.

Methods  Three groups of rats were used: (1) a stimulation group (n=12), (2) a sham stimulation group (n=12) with seizures induced by stereotactic administration of kainic acid (KA), and (3) a control group (n=12) with sham surgery. Concentric bipolar electrodes were stereotaxically implanted unilaterally in the ANT. High-frequency stimulation was performed in each group except the sham stimulation group. Microdialysis probes were lowered into the CA3 region of the hippocampus unilaterally but bilaterally in the stimulation group. The concentrations of glucose, lactate, and pyruvate in dialysate samples were determined by an ISCUS microdialysis analyzer.

Results  The extracellular concentrations of lactate and lactate/pyruvate ratio (LPR) of epileptic rats were significantly higher than in control rats (P=0.020, P=0.001; respectively). However, no significant difference in the concentration of glucose and pyruvate was found between these groups (P >0.05). Electrical stimulation of ANT induced decreases in lactate and LPR in the ipsilateral hippocampus (KA injected) of the stimulation group (P <0.05), but it did not influence the glucose metabolism in the contralateral hippocampus (P >0.05).

Conclusions  This study demonstrated that the glycolysis was inhibited in the ipsilateral hippocampus of epileptic rats during electrical ANT stimulation. These findings may provide useful information for better understanding the mechanism of ANT-deep brain stimulation.

Effect of anterior nucleus of thalamus stimulation on glucose metabolism in hippocampus of epileptic rats

Background  Electrical stimulation of the anterior nucleus of the thalamus (ANT) appears to be effective against seizures. In this study, we investigated changes in glucose metabolism during high-frequency stimulation of ANT in epileptic rats.

Methods  Three groups of rats were used: (1) a stimulation group (n=12), (2) a sham stimulation group (n=12) with seizures induced by stereotactic administration of kainic acid (KA), and (3) a control group (n=12) with sham surgery. Concentric bipolar electrodes were stereotaxically implanted unilaterally in the ANT. High-frequency stimulation was performed in each group except the sham stimulation group. Microdialysis probes were lowered into the CA3 region of the hippocampus unilaterally but bilaterally in the stimulation group. The concentrations of glucose, lactate, and pyruvate in dialysate samples were determined by an ISCUS microdialysis analyzer.

Results  The extracellular concentrations of lactate and lactate/pyruvate ratio (LPR) of epileptic rats were significantly higher than in control rats (P=0.020, P=0.001; respectively). However, no significant difference in the concentration of glucose and pyruvate was found between these groups (P >0.05). Electrical stimulation of ANT induced decreases in lactate and LPR in the ipsilateral hippocampus (KA injected) of the stimulation group (P <0.05), but it did not influence the glucose metabolism in the contralateral hippocampus (P >0.05).

Conclusions  This study demonstrated that the glycolysis was inhibited in the ipsilateral hippocampus of epileptic rats during electrical ANT stimulation. These findings may provide useful information for better understanding the mechanism of ANT-deep brain stimulation.