EFFECTS OF SYSTEMIC OR ORAL AD-LIBITUM MONOSODIUM GLUTAMATE ADMINISTRATION ON STRIATAL GLUTAMATE RELEASE, AS MEASURED USING MICRODIALYSIS IN FREELY MOVING RATS

We examined effects of high doses of monosodium glutamate (MSG) on ext racellular glutamate levels in rat striata, using in vivo microdialysi s. Parenteral doses (0.5, 1.0 and 2.0, but not 0.25, g/kg, i.p.) cause d dose- and time-dependent increases, peaking after 40 min (at 174 +/- 47%, 485 +/- 99% and 1021 +/- 301% of basal levels, respectively). In contrast, dietary MSG (1.49 +/- 0.10 g/kg/h) was ineffective.