Measurement of gamma-aminobutyric acid in human cerebrospinal fluid: radioreceptor assay using [3H]muscimol.

A method is described for the determination of gamma-aminobutyric acid (GABA) levels in human cerebrospinal fluid by modification of the radioreceptor assay utilizing [3H]muscimol as labelled ligand. This method is compared with the radioreceptor assay using [3H]GABA as labelled ligand. Although the [3H]muscimol assay is less sensitive than the [3H]GABA method, it offers the advantage of being more rapid due to the use of a filtration step instead of the usual, more time-consuming centrifugation of the samples. Samples of CSF of patients with various neurological or psychiatric disturbances were analysed. There was a satisfactory correlation between the GABA values obtained by the two assays.