Abstract
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Objectives Dopamine (D2) receptor lateral asymmetry of the striatum has been found previously via in vitro techniques in Sprague-Dawley rats (Schneider, 1982). In PET imaging animal models of Parkinson’s disease, one striatum is sometimes lesioned while the other is imaged as the control. The present study examined whether or not striatal D2 receptor laterality could be detected in Wistars and alcohol-preferring (P) rats using small animal PET.
Methods [11C]Raclopride PET images were acquired from 27 male Wistar and 26 male P rats. Scans were performed on IndyPETIII (approximately 1 mm FWHM in-plane; Rouze, 2005). Prior to each scan, rats were anesthetized with either isoflurane or ketamine/xylazine cocktail and secured on a stereotactic-like holder (Cheng, 2009). Anesthesia was maintained throughout a 75 minute scan. Time activity curves were extracted from left and right striatum and cerebellum and binding potentials (BPND) were calculated by a multilinear Logan reference technique (Ichise, 2002; Logan, 1996). ANOVAs were used to determine statistical significance (Microsoft Excel 2007 and SPSS 17.0.2).
Results In Wistars, BPND was significantly (n=27, p < 0.05) higher in the left striatum than the right striatum (7.48 +/- 9.98%, mean +/- SD). In P rats, BPND was higher in the left striatum than the right striatum (4.32 +/- 8.67%), but this finding was not significant (n=26, p > 0.1).
Conclusions We were able to detect lateral asymmetry of striatal D2 receptors in Wistars using small animal PET imaging with [11C]raclopride. This result suggests that corrections may be needed for laterality in imaging studies where one striatum is used as a control and the other is lesioned or its dopamine response otherwise manipulated experimentally. Lack of detectable D2 receptor asymmetry in P rats may indicate that this is a physiological trait specific to the P rat line