The effect of prolonged exposure to morphine on canine cerebral 5-HT2A receptors measured with 123I-R91150 SPECT

• Published in: European neuropsychopharmacology Vol. 24; no. 7; pp. 1133 - 1138
• Main Authors: Adriaens, Antita, Polis, Ingeborgh, Vermeire, Simon, Waelbers, Tim, Croubels, Siska, Duchateau, Luc, Van Dorpe, Sylvia, Eersels, Jos, De Spiegeleer, Bart, Peremans, Kathelijne
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2014
• Subjects: 123I-R91150; 5-HT2A; Dogs; Morphine; SPECT; Morphine; 123I-R91150; SPECT; Dogs; 5-HT2A
• ISSN: 0924-977X; 1873-7862
• DOI: 10.1016/j.euroneuro.2014.03.004

Down-stream neuronal alterations, including changes in the 5-HT-2A receptor system, play an important role in the etiology and treatment of depression. The present study examined the effect of prolonged opioid treatment on cerebral 5-HT2A receptors. Cerebral 5-HT2A receptor availability was estimated in seven healthy five-year-old female neutered Beagle dogs pre and post 10-day morphine treatment (oral sustained release morphine 20mg twice daily for 10 days) with 123I-R-91150, a 5-HT2A selective radioligand, and SPECT. 5-HT2A receptor binding indices (BI) for the frontal, parietal, temporal and occipital cortex and the subcortical region were calculated. Statistical analysis was performed using a linear mixed-effect model with treatment as fixed effect and dog as random effect. Morphine treatment significantly (P≤0.05) lowered 5-HT2A BIs in the right and left frontal cortex, the right and left temporal cortex, the right and left parietal cortex, and the subcortical region. The decreased cerebral 5-HT2A receptor availability following prolonged morphine exposure provides further evidence for an interaction between the opioid and serotonergic system.