Rabbit antisera have been raised against purified gerbil albumin and used for the immunocytochemical localization of the extravasated protein in brain following repeated ischemic results. A striking accumulation of albumin immunoreactivity was evident in thalamus as early as 6 hours after a series of repeated 5 minute carotid artery occlusions while positive staining was first evident in this region at 24 hours following repeated 2 minute occlusions. At longer recirculation intervals, thalamic staining was intensified and the CAl region of hippocampus showed strong immunoreactivity which accompanied the degeneration of neurons in this vulnerable area. In general, albumin immunoreactivity was closely correlated with the distribution of enhanced 45calcium 45uptake as well as with the appearance of reactive glia, as evidenced by immunocytochemical visualization of glial fibrillary acidic protein. The similarity of intraneuronal uptake of albumin to the endocytotic uptake of a protein tracer, observed in epileptic convulsions, suggests that neuroexcitatory mechanisms may be involved in uptake of proteins from the extracellular space in both conditions.
