Effect of dextromethorphan, a NMDA antagonist, on DNA repair in rat photochemical thrombotic cerebral ischemia

Photochemical thrombotic ischemia model was used to study the possible role s of excision repair cross-complementing group 6 (ERCC6), a DNA repair gene , in the neuroprotection of dextromethorphan (DM), a NMDA antagonist, in is chemic brain injury. The results showed that no obvious ERCC6 mRNA expressi on was found in the perifocal area of irradiated cerebral cortex before 24 h postischemia. Then, the number of ERCC6 mRNA positive cells gradually enh anced, and attained a peak value at 72 h after light irradiation, which fol lowed a declined tendency at 7-day postlesion. These results suggest that D NA repair gene ERCC6 mRNA expression in the perifocal area may be involved in the pathophysiological processes following the photochemical thrombotic cerebral ischemia. By the administration of DM, we observed that it can sig nificantly upregulate the expression of ERCC6 mRNA in the perifocal area at 48 h after ischemic event. The neuroprotective mechanisms of DM may be rel ated to the upregulation of DNA repair gene ERCC6 mRNA. (C) 1999 Elsevier S cience B.V. All rights reserved.