Intrahippocampal D-cycloserine improves MK-801-induced memory deficits: radial-arm maze performance in rats

In order to investigate whether strychnine-insensitive glycine sites coupled with hippocampal NMDA( N-methyl-D-aspartate) receptors are involved in spatial memory in rats, we examined the effects of intrahippocampal treatment of D-cycloserine (DCS), a glycine-site agonist, on spatial-memory deficits which were produced by an NMDA antagonist MK-801 (dizocilpine) on the radial-arm maze task. After the acquisition of this task, the radial-maze performance was tested under the combined treatments of intraperitoneal MK-801 or saline (SAL) and intrahippocampal DCS or SAL. The results showed that MK-801 impaired the performance, and that DCS improved the MK-801-induced performance impairment. These results suggest that glycine sites are involved in spatial memory through their modulatory action on hippocampal NMDA receptors. (C) 1998 Elsevier Science B.V. All rights reserved.