Immunohistopathologic analysis of olfactory degeneration caused by ischemia.

The development of olfactory dysfunction caused by ischemia was studied in Mongolian gerbils. Mongolian gerbils frequently have an anomaly of the cerebral circulation and are susceptible to brain ischemia or infarction following ligation of a single common carotid artery. Ischemia was induced by unilateral common carotid artery ligation or temporary occlusion of both common carotid arteries, and the olfactory pathway was examined. In the olfactory pathway of the forebrain, ischemic changes were observed in the lateral olfactory tract, olfactory tubercle, olfactory ventricle, and anterior olfactory nucleus. The olfactory bulb was resistant to ischemia. Partial or complete degeneration of the ipsilateral olfactory neuroepithelium was observed in some gerbils that survived more than 14 days after the onset of ischemia. Immunohistopathologic analysis of the neuroepithelium for the olfactory marker protein revealed that functional damage of the olfactory neurons occurred in some gerbils within the first few days after the ischemic event.