Effect of ketamine on the regional cerebral blood flow and binding index of the 5-HT2A receptor radioligand 123I-R91150 in the canine brain

Ketamine, a dissociative anesthetic frequently used in veterinary medicine, possesses rapid-acting antidepressant effects in humans possibly indicating an interaction with the cerebral perfusion or with the serotonergic system. In this single-photon emission computed tomography study, 7 healthy dogs were used to investigate the influence of ketamine on the regional cerebral blood flow using technetium-99m-ethyl cysteinate dimer and on the binding of the 5-hydroxytryptamine 2A receptor radioligand iodine-123 labeled R91150 in the canine brain. Ketamine increased the regional perfusion in the left frontal cortex and right parietal cortex. Significant changes in the distribution of iodine-123 labeled R91150 were not observed. This study demonstrated an acute effect of ketamine on the regional brain perfusion but not on the 5-hydroxytryptamine 2A receptors in the canine brain in the dose used in this study.