Characterization of the gamma-aminobutyric acid receptor system in human brain gliomas

The properties of [3H]-gamma-aminobutyric acid [( 3H]GABA) binding were studied in biopsied specimens from normal human brain and from 18 cases of human brain gliomas, made up of 6 astrocytomas, 6 glioblastomas, 3 oligodendrogliomas, and 3 medulloblastomas. In fresh membranes obtained from normal gray and white matter one population of Na+-dependent GABA receptors was observed, while in the frozen Triton X-100-treated membranes two distinct populations of Na+-independent binding sites were detected. Specific GABA binding sites in brain gliomas were shown only in frozen Triton X-100-treated membranes. As in normal tissue, these receptors are Na+-independent and bind [3H]GABA with two distinct affinity components. The biochemical profiles of [3H]GABA binding to membranes obtained from different tumors of glial origin are quite similar and cannot be related to the degree of malignancy of the neoplasia.