Fig. 2.

Brain atrophy and cholinergic degeneration is more pronounced in aged versus young adult C57BL/6 mice following stroke. a Representative 4× images of Nissl-stained whole brain sections from 3 and 18 month-old (mo), sham- and stroke-operated C57BL/6 mice at 8 weeks post-surgery. b Representative 2× images of Nissl-stained cortical layers I-VI of the ipsilateral primary somatosensory cortex in 3 and 18 mo, sham- and stroke-operated mice at 8 weeks post-surgery. Scale bar, 250 μm. c Quantification of the lateral ventricle (left graph) in the ipsilateral hemisphere revealed significant ventricle enlargement in the 18 mo stroked mice relative to the age-matched sham-operated mice. Furthermore, the 18 mo stroked mice had a significantly larger ventricle area compared to the 3 mo stroked mice. Quantification of cortical thickness (right graph) in the ipsilateral hemisphere revealed significant tissue loss or shrinkage in both the 3 and 18 mo stroked mice relative to age-matched sham-operated mice. Furthermore, the 18 mo stroked mice had significantly more tissue loss compared to the 3 mo stroke mice. d Representative 5× images of choline acetyltransferase (ChAT)-immunolabeled neuronal cell bodies, their neurites, and innervating projection fibers in the medial septum of the basal forebrain in 3 and 18 mo, sham- and stroke-operated C57BL/6 mice at 8 weeks post-surgery. Many neurites (arrows) in the stroked mice displayed qualitative degenerative changes, including decreased length relative to sham mice. Scale bar, 100 μm. e Quantification of cholinergic somas, neurites, and fibers revealed a significant reduction of ChAT+ staining in both the 3 and 18 mo stroked mice relative to the age-matched sham mice. Furthermore, the 18 mo stroked mice exhibited significantly more loss of ChAT+ staining compared to the 3 mo stroked mice. Data represent mean ± SEM. *p<0.05, **p<0.01, and ****p<0.0001