Monosodium L-glutamate-induced convulsions: changes in uptake and release of catecholamines in cerebral cortex and caudate nucleus of adult rats.

Adult rats (60 days old) were injected intraperitoneally with 5 mg/g monosodium L-glutamate (MSG). During the convulsive period (1 h after injection), uptake and release of [3H]norepinephrine (3H-NE) and [14C]dopamine (14C-DA) were measured in a crude synaptosomal fraction and in slices of cerebral cortex and caudate nucleus, respectively. A significant reduction of 3H-NE uptake was detected in cortical slices (by 42%) and in synaptosomal fraction (by 33%) of rats treated with MSG, whereas K+- stimulated 3H-NE release was decreased by 32% and 39% in brain slices and in a synaptosomal fraction of cerebral cortex, respectively, in comparison with animals injected with 0.9% NaCl aqueous solution (PSS). In the caudate nucleus, 14C-DA uptake was increased by 100% in brain slices and by 36% in the synaptosomal fraction following MSG administration, whereas K+- stimulated 14C-DA release was enhanced by 80% in slices and by 25% in synaptosomes as compared to PSS-injected rats. Data suggest that catecholaminergic neurotransmission may play an important role in the etiopathology of convulsions in the experimental model using MSG.