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Neurosciences: Basic ScienceBasic Science Posters |
1 Radiology and VUIIS; 2 Pharmacology; 3 Radiology, Vanderbilt University, Nashville, Tennessee
897
Objectives: Rodent MicroPET imaging with [18F]Fallypride is one method to estimate the binding potential (BP) of brain D2 receptors. There are conflicting reports in the literature on the effect of anesthesia on dopamine release. Our aim in this study was to investigate the influence of isoflurane anesthesia on the occupancy of D2 receptors.
Methods: Three groups of Sprague-Dawley rats were scanned on the microPET Focus 220. In these experiments, 17 MBq of [18F]Fallypride was administered via a tail vein catheter. Group 1 (N = 6) was anesthetized with 1.5% isoflurane and imaged for 120 min. The tracer was administered 30 sec after the start of the scan. Group 2 (N = 6) was anesthetized, injected with the tracer, allowed to wake up unrestrained for 60 min, then anesthetized again and scanned for 60 min. In group 3 (N = 3), the rats were restrained and injected consciously. They were imaged 60 min later for 60 min. One week later both groups 2 and 3 were imaged for 120 min as for group 1. Attenuation corrections were performed using a 57Co transmission scan. Images were reconstructed using OSEM2D algorithm. The BP was estimated using a Logan plot.
Results: Estimates of the BP using the last 50 min of a 120 min scan varied by 4% from the BP estimates of the full 120 min data, validating that stable BP estimates could be obtained without inclusion of the first 70 min. BP estimates of conscious versus unconscious uptake varied by 44% in the second group and 16% in the third group.
Conclusions: Isoflurane reduces the D2 BP by up to 44%, indicating a reduction in available D2 receptors.
Research Support: NIH/NCRR 1S10RR17858 and /NIMH R21MH68757 (Bethesda, MD), and Burroughs Welcome Fund CASI (RTP, NC).
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