Ken-Ichi Saito

The anxiolytic-like effect of MCI-225, a selective NA reuptake inhibitor with 5-HT3 receptor antagonism.

We have previously reported that MCI-225, a selective noradrenaline (NA) reuptake inhibitor with serotonin (5-HT)3 receptor antagonism, shows antidepressant-like properties in experiments using rodents. In this study, we investigated the effect of MCI-225 in anxiety models in comparison with diazepam, ondansetron, maprotiline, imipramine, and trazodone. In social interaction (SI) test in rats, MCI-225 (10 and 30 mg/kg, p.o.), diazepam (1-10 mg/kg, p.o.), and a selective 5-HT3 receptor antagonist ondansetron (1 mg/kg, p.o.) significantly increas

MKC-231, a choline uptake enhancer: (3) mode of action of MKC-231 in the enhancement of high-affinity choline uptake

MKC-231, a putative cholinergic activity, is reported to improve learning and memory impaired in AF64A-treated animals. MKC-231 enhances high-affinity choline uptake (HACU) known as the rate-limiting step of acetylcholine (ACh) synthesis. We investigated the mode of action (MOA) of HACU enhancement by MKC-231. Intracerebroventricular (i.c.v.) injections of AF64A (3xa0nmol/brain) resulted in significant HACU reduction in hippocampal synaptosomes. Treatment with MKC-231 increased Vmax of HACU and Bmax of [3H]-HC-3 binding 1.6 and 1.7-fold, respectively. In studies of [3H]-MKC-231 binding and Biacore analysis, MKC-231 showed noticeable affinity for cloned high-affinity choline transporters (CHT1). The present study suggests that MKC-231 directly affects trafficking of CHT1 and increases the numbers of transporter, working for HACU, at the synaptic membrane.

MCI-225, A Novel Thienopyrimidine Analog, Enhances Attentional Eye Tracking in Midpontine Pretrigeminal Preparation

The effects of MCI-225, a novel psychoactive compound, and reference drugs on attention behavior were studied using visual stimulus induced vertical eye tracking movements in midpontine pretrigeminal (PTG) feline preparation. Surgery was performed under ether anesthesia and subsequently switched to nitrous oxide-fluothane which was discontinued only during experimental sessions. In addition xylocaine was locally injected. Vertical eye movements were monitored by electrooculogram (EOG) and a TV camera. To compare the effects of drugs on eye movement, numbers of spontaneous and tracking eye movements exceeding a present amplitude in EOG were counted before and during the visual stimulation, respectively. MCI-225 (1 and 3 mg/kg, i.v.) enhanced tracking movements dose-dependently without an increase in spontaneous eye movements. No or little change of the electrocorticogram (ECoG) was seen with 1 mg/kg MCI-225 and a slight increase in low voltage fast pattern was observed with 3 mg/kg, i.v.. On the other hand, tacrine (0.3 mg/kg, i.v.), physostigmine (0.03 mg/kg, i.v.) and methylphenidate (0.3 mg/kg, i.v.) enhanced both types of eye movement and induced ECoG arousal. Desipramine (3 mg/kg, i.v.) slightly increased spontaneous eye movement without affecting tracking movements. Piracetam (100 mg/kg, i.v.) decreased spontaneous eye movements only. These data clearly show that MCI-225 enhances attention to a moving object and suggest that MCI-225 could be useful in the treatment of attentional deficits and related cognitive dysfunctions in psychiatric disorders.