抄録
N-methyl-D-aspartate (NMDA) receptors is thought to underlie certain types of learning and memory. In laboratory animals, treatment with NMDA receptor an-tagonist impaired spatial learning in a watermaze task. This study was undertaken to assess the behavioral effects of MK-801 [(±)-5-methyl-10, 11-dihydro-5H-dibenzo [a, d] cyclohepten-5, 10-imine maleate], on the acquisition of dynamic equilibrium in guinea pigs. We used the milk maze test (Morris et al, 1986) as a spatial learning test, and used the beam-walking test (Feeney et al, 1981, 1982) for dynamic equilibrium training. We observed that guinea pigs were able to traverse a narrow elevated beam to acquire dynamic equilibrium. We trained guinea pigs twice a day for a period of 12 days. Although MK-801, (0.07 mg/kg, i.p., n=6) impaired spatial learning during milk maze test, dynamic equilibrium during the beam-walking test (0.07 mg/kg, i.p., n=8) was not affected in the control group receiving an equal volume of saline injections. These results confirm that MK-801-induced impairment of spatial learning is due to the inhibition of NMDA receptors as previously reported. However, NMDA receptors may not play the same role in acquiring dynamic equilibrium, and this may be due to differences between the parts of the brain involved in learning and acquiring dynamic equilibrium.
