Increase in ?3 (Peripheral-Type Benzodiazepine) binding site densities in different types of human brain tumours

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Abstract
The density of ω3 (peripheral type benzodiazepine) binding sites, a marker of reactive and tumoural cells, has been measured in different types of human brain tumours; ω3 sites were quantified autoradiographically in sections from biopsy or autopsy specimens labelled with the specific radioligand3H-PK 11195. Compared to normal brain parenchyma, up to 12-fold increase in ω3 site densities were found in appparently 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) ω3 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 ω3 site densities. These results suggest that ω3 site densities in human brain tumours reflect their proliferative activity and point to a possible future usefulness of positron or gamma-ray emitting ω3 site ligands for the clinical investigation and detection of human brain proliferative diseases.