ALTERATIONS OF A 200 KDA NEUROFILAMENT IN THE RAT HIPPOCAMPUS AFTER FOREBRAIN ISCHEMIA

Alteration in the concentration of a 200 kDa neurofilament (NF200) in the rat hippocampus after forebrain ischemia and its relationship to h ippocampal neuronal death were studied with an anti-200 kDa neurofilam ent antibody, using immunohistochemical and immunoblotting techniques. In rats subjected to 8 min of transient forebrain ischemia, hematoxyl in-eosin staining showed survival of most of the neurons in the hippoc ampal CA1 region at 1 day and loss of more than 75% of the neurons at 7 days after ischemia. Immunoblotting showed that the concentration of NF200 in the hippocampal homogenate tended to decrease after ischemia , to 69% of that of control at 1 day and to 60% of the control value a t 7 days after 8 min of forebrain ischemia. Following 5 min of ischemi a as well, the decrease in the concentration of neurofilaments in the hippocampal region preceded histological confirmation of neuronal cell death. These results suggest that degradation of neurofilament triple t proteins occurred even after ischemia of minimal duration and preced ed neuronal death. Degradation of cytoskeletal proteins may play an im portant role in the mechanism of delayed neuronal death after cerebral ischemia.