This study investigates the effects of deep brain stimulation (DBS) on glucose metabolism in the rat brain using FDG-PET imaging. The methodology involves the administration of a radiolabeled glucose analog and subsequent imaging to assess metabolic activity.
Take an anesthetized rat with deep brain stimulation or DBS electrodes implanted in the medial prefrontal cortex.
Inject FDG, a radiolabeled glucose analog, through the lateral tail vein.
FDG crosses the blood-brain barrier via glucose transporters, and reaches the brain.
Prepare the stimulator setup in a quiet environment to minimize potentially disturbing stimuli.
Connect the stimulation wires to the electrodes.
Start DBS. High-frequency electrical pulses depolarize neuronal membranes, enhancing synaptic activity.
This increases neuronal ATP consumption, accelerating glucose metabolism to replenish ATP levels.
Enhanced glucose utilization increases FDG uptake in metabolically active neurons and glia, where it undergoes phosphorylation and accumulation.
Stop the stimulation. Capture PET and CT brain images and generate brain maps.
Increased FDG uptake indicates more active brain regions, while less active areas show lower uptake, revealing DBS-induced metabolic neuromodulation.
Fill a 27 gauge syringe with approximately 37 megabecquerel of the FDG solution in the least possible volume as measured in an activimeter. Place a heating pad under the animal's tail or use infrared light to dilate the tail veins. Inject the FDG solution through one of the lateral tail veins.
Place the animal back in the cage and allow 45 minutes for radio tracer uptake before initiating the image acquisition session. For the D2 study, deliver DBS during the FDG uptake period. Prepare the isolated stimulator and the required wires in a vast and quiet room with enough space for the animal cages and minimal influence of potentially disturbing stimuli.
Connect the stimulation wires to the swivels to allow animals to freely move within the cages and to the stimulator. Set the stimulation parameters as described in the text manuscript. Use an oscilloscope to check the current mode, frequency, and pulse width.
Confirm the biphasic wave form with a rectangular pulse shape. The CT image clearly visualized the electrode inserted into the rat brain. The imaging modality used in this study also provided good anatomical information and facilitated the registration of FDG-PET images.
A fused PET-CT image of the same animal spatially registered to the same stereotaxic space. The brain metabolic differences were observed between PET sessions as T-maps superimposed on sequential one millimeter brain slices from an MRI registered to the reference CT image. These differences consisted of increases and decreases in FDG uptake shown as warm and cold colors respectively.
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