Heme oxygenase in the experimental ALS mouse.

Heme oxygenase-1 (HO-1) is a stress protein inducible in some cells by oxidative stress. The status of heme oxygenase was investigated in a transgenic mouse model of amyotrophic lateral sclerosis (ALS) since oxidative mechanisms are postulated in neuronal injury. Three ALS mice [(SOD1-G93A)1Gur] and three controls [(SOD-1)2Gur] were obtained from The Jackson Laboratory. Behavioral differences suggestive of neurodegeneration in ALS mice developed at 4-5 months of age. All mice were killed at 7-8 months of age. Tissue vacuolation, cell loss, and the presence of GFAP+ cells were noted in the spinal cords of ALS mice. Spinal cord motor neurons in both control and ALS mice stained positive for heme oxygenase-2 (HO-2). While not precluding the presence of low levels of HO-1 neither immunohistochemical staining nor Western blot analysis provided evidence for significant HO-1 induction in degenerating spinal cord.