A new model of localized ischemia in rat somatosensory cortex produced by cortical compression

Background and Purpose-Because of its precise connectivity and functional s pecificity, the rat whisker-barrel system offers an excellent opportunity t o study experience-dependent neuroplasticity. However, data are lacking reg arding the neuroplasticity of this system after cerebral ischemia. The purp ose of the present study was to develop a reproducible model for the produc tion of ischemia/reperfusion of the posteromedial barrel subfield (PMBSF) i n the rat, which is the visible representation of the large whiskers on the opposite face. Methods-Focal cortical ischemia was induced in male Sprague-Dawley rats (n = 40) by slowly compressing the intact dura (maximum 0.05 mm/s) with a 4- o r 5-mm-diameter brass cylinder equipped with a laser-Doppler probe, combine d with ipsilateral common carotid artery occlusion. The microvascular blood flow of PMBSF during compression ischemia was maintained at 18% to 20% of baseline flow for 1 hour. The total infarction volume was measured by 2,3,5 -triphenyltetrazolium chloride staining at several reperfusion times, and p athological examination was performed on hematoxylineosin-stained sections. Results-The infarct volumes were 36.5 +/- 9.2 (n = 9), 40.7 +/- 7.7 (n = 7) , and 36.6 +/- 6.4 mm(3) (n = 5) at 24 hours, 72 hours, and 7 days after is chemia, respectively, with no significant differences among these values. T here was no evidence of damage to white matter or to deep gray matter and n o evidence of hemorrhage. The topographic distribution of the damaged tissu e was in good agreement with that of PMBSF. Conclusions-This stroke model produces a highly consistent cortical infarct in PMBSF and can facilitate the study of behavioral, functional, and struc tural consequences after cerebral ischemia/reperfusion in the rat somatosen sory Cortex.