Widespread up-regulation of N-methyl-D-aspartate receptors after focal photothrombotic lesion in rat brain

Following focal brain lesions, complex adaptive processes take place in rem ote intact areas. The present study examines changes in NMDA (N-methyl-D-as partate), AMPA ((+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic a cid) and kainate receptors following focal photothrombotic ischemic lesions using quantitative receptor autoradiography. Increases in binding density of NMDA receptors were seen in both hemispheres for up to 30 days. In the c ontralateral hemisphere, this increase of NMDA receptors occurred as early as 4 h after lesion whereas it appeared with a delay for 14 days on the les ioned side. Binding density of [H-3]AMPA and [H-3]kainate was unchanged. We suggest that the translational process is differentially regulated by spre ading depressions. The delayed up-regulation of NMDA receptor binding on th e lesioned side may be due to a translation block similar to that previousl y described for GABA(A) receptor subunits. (C) 1999 Elsevier Science Irelan d Ltd. All rights reserved.