5-HT2A Receptors in the Feline Brain: 123I-5-I-R91150 Kinetics and the Influence of Ketamine Measured with Micro-SPECT

Journal of Nuclear Medicine

Jos Eersels¹  Guido Slegers¹  Simon Vermeire¹  André Dobbeleir¹  Ingeborgh Polis¹  Tim Waelbers¹  Kathelijne Peremans¹  Bart De Spiegeleer¹  Kurt Audenaert¹ 

关键词: ketamine;    cats;    brain;    5-HT_2A;    SPECT;   

DOI  :  10.2967/jnumed.112.114637

学科分类：医学（综合）

来源: Society of Nuclear Medicine

【 摘 要 】

Subanesthetic doses of ketamine can be used as a rapid-acting antidepressant in patients with treatment-resistant depression. Therefore, the brain kinetics of 123I-5-I-R91150 (4-amino-N-[1-[3-(4-fluorophenyl)propyl]-4-methylpiperidin-4-yl]-5-iodo-2-methoxybenzamide) and the influence of ketamine on the postsynaptic serotonin-2A receptor (5-hydroxytryptamine-2A, or 5-HT2A) status were investigated in cats using micro-SPECT. Methods: This study was conducted on 6 cats using the radioligand 123I-5-I-R91150, a 5-HT2A receptor antagonist, as the imaging probe. Anesthesia was induced and maintained with a continuous-rate infusion of propofol (8.4 ± 1.2 mg kg−1 followed by 0.22 mg kg−1 min−1) 75 min after tracer administration, and acquisition of the first image began 15 min after induction of anesthesia. After this first acquisition, propofol (0.22 mg kg−1 min−1) was combined with ketamine (5 mg kg−1 followed by 0.023 mg kg−1 min−1), and the second acquisition began 15 min later. Semiquantification, with the cerebellum as a reference region, was performed to calculate the 5-HT2A receptor binding indices (parameter for available receptor density) in the frontal and temporal cortices. The binding indices were analyzed with Wilcoxon signed ranks statistics. Results: The addition of ketamine to the propofol continuous-rate infusion resulted in decreased binding indices in the right frontal cortex (1.25 ± 0.22 vs. 1.45 ± 0.16; P = 0.028), left frontal cortex (1.34 ± 0.15 vs. 1.49 ± 0.10; P = 0.028), right temporal cortex (1.30 ± 0.17 vs. 1.45 ± 0.09; P = 0.046), and left temporal cortex (1.41 ± 0.20 vs. 1.52 ± 0.20; P = 0.046). Conclusion: This study showed that cats can be used as an animal model for studying alterations of the 5-HT2A receptor status with 123I-5-I-R91150 micro-SPECT. Furthermore, an interaction between ketamine and the 5-HT2A receptors resulting in decreased binding of 123I-5-I-R91150 in the frontal and temporal cortices was demonstrated. Whether the decreased radioligand binding resulted from a direct competition between ketamine and 123I-5-I-R91150 or from a decreased affinity of the 5-HT2A receptor caused by ketamine remains to be elucidated.

【 授权许可】

Unknown