Factors influencing concentrations of GABA in cerebrospinal fluid

Abstract

Degradation of cerebrospinal fluid (CSF) constituents occurring during collection, storage and analysis may add artifactual variations to CSF data. GABA levels in untreated CSF determined by ion-exchange/fluorometric assay remained stable when stored at −70°C for 3.5 years and at −20°C for 1.5 years. GABA concentrations in untreated CSF doubled during 2 hours at room temperature but did not significantly change during 10 minutes at room temperature or 2 hours at 4°C. GABA levels in deproteinized CSF were stable at −70°C but doubled during 11 months of storage at −20°C. GABA concentrations in deproteinized CSF were stable for 49 hours at room temperature but increased 1.3 -fold and 2.0 -fold after 3 weeks at 4°C and room temperature, respectively. The GABA content of homocarnosine standards in 0.1 N HCl similarly increased during storage at room temperature and at −20°C suggesting that the GABA elevations in inadequately stored or prepared CSF may be secondary to GABA-containing peptide degradation.