Effect of NOS inhibitors and exogenous NO and NMDAR antagonists on the survival of CA1 pyramidal neurons. A, cresyl violet staining was performed on sections from the hippocampi of sham-operated rats (panels a and b) and of rats subjected to 5 days of reperfusion after global ischemia (panels c and d), and the administration of saline (panels e and f), DMSO (panels g and h), 7-NI (panels i and j), SNP (panels k and l), MK801 (panels m and n), GSNO (panels o and p), TE (panels q and r), MS-nNOS (panels s and t), and AS-nNOS (panels u and v) before or after ischemia. Cresyl violet staining data were obtained from six independent animals, and a typical experiment is presented. B, cell density was expressed as the number of cells per 1-mm length of the CA1 pyramidal cells counted under a light microscope. Data are the mean ± S.D. (n = 6). Scale bars, 300 μm (panels a, c, e, g, i, k, m, o, q, s, and u); 30 μm (panels b, d, f, h, j, l, n, p, r, t, and v). a, p < 0.05 versus the sham groups; b, p < 0.05 versus the saline groups.