ALZ-50 AND UBIQUITIN IMMUNOREACTIVITY IS INDUCED BY PERMANENT FOCAL CEREBRAL-ISCHEMIA IN THE CAT

The effects of permanent focal cerebral ischaemia on Alz-50 and ubiqui tin antibody immunohistochemical staining were investigated in vivo in the cat. Alz-50 and ubiquitin antibody staining was compared to the d istribution of ischaemic cell damage. Six hours following permanent oc clusion of one middle cerebral artery, Alz-50 immunoreactivity was pre sent in neurones in the ipsilateral ischaemic cerebral cortex and caud ate nucleus but not in any region of the contralateral hemisphere or i n sham-operated cats. Only a proportion of neurones were stained with Alz-50 and these did not have the shrunken, pyknotic appearance charac teristic of irreversible ischaemic cell damage. Ubiquitin immunoreacti vity was also increased in the ischaemic hemisphere, again only a prop ortion of neurones were stained. The Alz-50 antibody recognises the mi crotubule-associated protein tau and stains neurofibrillary tangles as well as neurones vulnerable to neurofibrillary change in tissue secti ons of Alzheimer brain. The results indicate that there are changes in tau protein in response to an ischaemic insult, but only in some neur ones,which may reflect an early stage of the degenerative process. Inc reased ubiquitin immunoreactivity may be a response to the presence of abnormal proteins, including tau, which are induced by an ischaemic c hallenge.