Early visual changes in reflected light on non-stained brain sections after focal ischemia mirror the area of ischemic damage

There is no reliable, simple method for delineation of ischemic regions at early time points after ischemia. We propose that at early times after stro ke, ischemic regions can be visualized as a subtle change in reflected ligh t directly in thaw-mounted, dried 20 gm brain sections. In 15 male Sprague- Dawley rats, anesthetized with isoflurane, middle cerebral artery transecti on and permanent bilateral common carotid artery occlusion was performed an d brains were processed in five different ways. Areas of reflective change (RC) on non-stained sections were compared with areas on the adjacent secti ons delineated by microtubule associated protein 2 (MAP2) antibody, a relia ble marker for early post-stroke, in five rats each at 1, 3, and 6 h after focal cerebral ischemia. A statistically significant correlation between is chemic areas (IA) measured on non-stained brain sections (IA(RC)) and adjac ent sections immunostained (IM) with MAP2 Ab (IA(IM)) (IA(RC) == 0.05 + 0.8 8-IA(IM); R-2 = 0.8; n = 15, P < 0.01) and a small mean difference +/-2 S.D . ( - 0.9 +/- 6.0%) indicated that the area measured on non-stained section s reflects the IA measured on MAP2 -IM sections. At 1 and 3 h after ischemi a, the ratio between ischemic regions measured on the non-stained sections and on the adjacent sections immunostained with MAP2 Ab were not different from 100% (97.6 +/- 1.7%, 100.9 +/- 6.0%). At 6 h post-stroke, the IA measu red on the non-stained sections was larger than on the IM sections (109.8 /- 2.7%, P < 0.01, compared to 100% ratio). Our study demonstrated that thi s quick and simple method for detection of damaged brain permitted the use of brain tissue for other assays and could be very useful for neuroprotecti ve evaluation and for directed micro-sampling of brain tissue at early time s after ischemia. (C) 2001 Elsevier Science B.V. All rights reserved.