Total GABA and homocarnosine in CSF as indices of brain GABA concentrations.

Treatment of rats with gamma-vinyl-GABA, an inhibitor of GABA-transaminase, caused a dose- and time-related increase in brain GABA concentrations concomitant with increases in the concentrations of total GABA and homocarnosine in the CSF. At 18 h after treatment both CSF parameters correlated significantly with brain GABA concentrations. However, only total GABA in CSF accurately reflected brain GABA concentrations as a function of time after treatment and is therefore the preferred index.