Abstract
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Objectives: Drug addiction is a chronic brain disease and the repeated use of drug occurs very often when drugs use is discontinued. However, the mechanism of drug addiction recurrence on brain is not clear. The aim of this study was to investigate the changes of cerebral glucose metabolism in morphine-induced and morphine-induced conditioned place preference (CPP) rats using FDG PET. Methods: Experimental group of conditioned place preference rats (n = 6) was established by intraperitoneal injection of morphine (6 mg/kg body weight) in male SD rats (250 - 300g) during three-day conditioning, and rats with only morphine injection were used as control group (n = 6). Micro-PET/CT scans were performed at 7 days before (Baseline) and 7, 14 days after morphine injection or under morphine-induced conditioned place preference. Static PET/CT imaging was obtained for 10 min at 60 min post intravenous injection of FDG. Imaging data were analyzed using MATLAB platform-based SPM8 software (P = 0.01, k = 20).
Results: After 14 days intraperitoneal injection of morphine, compared with control group, CPP group was significantly increased in the dorsal tegmental nucleus and reduced in the primary somatosensory cortex (P < 0.01, k > 20) [Fig 1, A]. Compared with baseline,CPP group was significantly increased in the hippocampus and primary somatosensory cortex, and decreased in the external globus pallidus (P < 0.01, k > 20) at 14 days after injection [Fig 1, B], and was significantly decreased in the hippocampus (P < 0.01, k > 20) at 14 days after injection [Fig 1, C]. Compared with at 7 days after injection, CPP group was significantly increased in the anterior pretectal nucleus and dorsal tegmental nucleus (P < 0.01, k > 20) and decreased in the hippocampus at 14 days after injection [Fig 1, D]. Compared with baseline, control group was significantly reduced in two regions at 7 days after injection: the caudate-putamen and primary somatosensory cortex (P < 0.01, k > 20) [Fig 2, A], and was significantly increased in the hippocampus (P < 0.01, k > 20) at 14 days after injection [Fig 2, B]. Meanwhile, compared with at 7 days after injection, control group was significantly increased in two regions at 14 days after injection: the primary somatosensory cortex and caudate-putamen (P < 0.01, k > 20) [Fig 2].Conclusion: This study shows that the cerebral glucose metabolism in CPP group is significantly different from control group from each time point, possibly involved in addiction recurrence. Research Support: This research project was supported by the National Natural Science Foundation of China (Project No. 81571345), the Research Center on Aging and Medicine, Fudan University (Project No: IDF151006), National Key Research and Development Program Foundation of China (No: 2016YFC1306403), Natural Science Foundation and Major Basic Research Program of Shanghai(NO: 16JC1420502), Natural Science Foundation and Major Basic Research Program of Shanghai (NO: 16JC1420100), Program of the Shanghai Science and Technology Commission (NO: 1751107103, 17411953500).