MKC-231, a choline-uptake enhancer: (1) long-lasting cognitive improvement after repeated administration in AF64A-treated rats

MKC-231 is reported to increase high-affinity choline uptake (HACU) in vitro and improve learning impairment on a single oral administration in AF64A-treated rats. In this study, we investigated the effects of repeated administration of MKC-231 (1 and 3 mg/kg, p.o., 8 days) on learning impairment in the water-maze task in AF64A-treated rats 1, 24, 48, and 72 h after the last dose. Significant cognitive improvement was observed for 24 h, however, concentration measurement studies indicated MKC-231 was not detected in the brain by this time. We also studied the effects of 8-days repeated administration of MKC-231 on HACU 1, 24, 48, and 72 h after the last dose and observed an increase of HACU similar in time course with cognitive improvement. From these results, we discussed the possibility that MKC-231 could induce long-lasting procognitive effects by changing the choline transporter regulation system.