TY - JOUR T1 - Distribution of opioid receptors in rat brain: An animal PET study with F-18-fluoroethyl-diprenorphine JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 217 LP - 217 VL - 51 IS - supplement 2 AU - Hans-Georg Buchholz AU - Katrin Meier AU - Julia Tillmanns AU - Rolf-Detlef Treede AU - Mathias Schreckenberger Y1 - 2010/05/01 UR - http://jnm.snmjournals.org/content/51/supplement_2/217.abstract N2 - 217 Objectives In human PET studies with F-18-fluoroethyl-diprenorphine (DPN) we found high binding potential (BPND) in areas of the lateral nociceptive system, i.e. the anterior insula cortex and the secondary somatosensory cortex (S2). Now we tested whether a similar opioid receptor (OR) distribution exists in rat brain in order to check the validity of an animal model for pain research. Methods 7 male Wistar rats were scanned under light chloralhydrate anaesthesia with DPN. BPND were calculated using the non-invasive Logan plot with the cerebellum as reference region input. Using PMOD software package a set of volume of interests (VOI) were defined on a MRI template in Paxinos space. BPND images were realigned to the MRI and spatially normalized to Paxinos orientation using SPM5. Averaged BPND (mean +/- SEM) for all VOI were calculated. Results BPND varied widely across the VOI. Highest BPND were found in the thalamus (2.65 +/- 0.23). Occipital cortex showed the lowest BPND (0.94+/-0.12). The BPND was significantly higher in the anterior cingulate cortex (2.11+/-0.21) than in midcingulate cortex (1.51+/-0.18). BPND were both higher in the anterior and posterior insula cortex than in S2, while in the sensory-motor strip BPND was lower than in S2. In contrast to human data, the cerebellum of the rat is nearly OR-free. For all other VOI the BPND showed a strong correlation to human BPND (r2 =0.85). Conclusions Similar to humans (except the cerebellum) the lateral nociceptive system in the rat expresses significant amounts of OR suggesting a phylogenetically conserved opioderegic control of the sensory-discriminative pain component ER -