Abstract
895
Objectives: Microdialysis experiments in rats have shown that intraperitoneal (i.p.) ethanol injections produce an increase in extracellular striatal dopamine (DA) (Heidbreder & De Witte, 1993). We sought to determine if we could detect similar changes in striatal DA using small animal PET and 11C-raclopride.
Methods: PET images were acquired from 8 alcohol-naïve rats (male, Wistar). Each rat received two 11C-raclopride scans (at rest and following alcohol) separated in time by at least 5 days. Scans were done on an in-house small animal scanner, IndyPETIII (approx. 1 mm FWHM in-plane). Before each scan, rats were anesthetized with 5% isoflurane and secured on a stereotactic holder 20 minutes before tracer injection. Isoflurane was maintained at 1.5% during scan. In alcohol studies, rats received 3g/kg ethanol i.p. (20%v/v) 5 minutes before tracer injection. Time activity curves were extracted from the striatum and the cerebellum and binding potentials (BP) were calculated by a Logan reference technique (Ichise, 2002).
Results: Average BP decreased by 13.3 +/- 13.2% (n = 8, p<0.05) after i.p. alcohol injection. Animals were noticeably inebriated after anesthesia wore off following scan. Average BP drop is 10.7 +/- 10.4 (n=7, p<.05) if the animal with strongest response is dropped.
Conclusions: IP alcohol given to anesthetized rats may cause sufficient release of striatal DA to be detectable as decreased 11C-raclopride BP via small animal PET. We are currently working to rule out possible confounding effects such as scan order or an effect of the i.p. injection. We observe a slight decrease in D2 receptors with age but not enough to account for the overall effect of alcohol.
Research Support: P60 AA007611-16
- Society of Nuclear Medicine, Inc.