INCREASE IN OMEGA-3 (PERIPHERAL-TYPE BENZODIAZEPINE) BINDING-SITE DENSITIES IN DIFFERENT TYPES OF HUMAN BRAIN-TUMORS - A QUANTITATIVE AUTORADIOGRAPHY STUDY

The density of omega3 (peripheral type benzodiazepine) binding sites, a marker of reactive and tumoural cells, has been measured in different types of human brain tumours; omega3 sites were quantified autoradiographically in sections from biopsy or autopsy specimens labelled with the specific radioligand H-3-PK 11195. Compared to normal brain parenchyma, up to 12-fold increase in omega3 site densities were found in apparently viable areas of high grade astrocytoma and glioblastoma specimens, whereas more limited increases (2 to 3-fold) in this marker were observed in areas of necrosis. Low grade gliomas (astrocytomas) and meningiomas exhibited only moderate increases (2 to 3-fold) in this autoradiographic marker. Metastases of lung or kidney origin were characterized by greatly elevated (up to 20-fold) omega3 site densities as compared to normal brain parenchyma. In every case, there was a good spatial correspondence between the histopathological limits of the tumour and the anatomical location of the increase in omega3 site densities. These results suggest that omega3 site densities in human brain tumours reflect their proliferative activity and point to a possible future usefulness of positron or gamma-ray emitting omega3 site ligands for the clinical investigation and detection of human brain proliferative diseases.