Effect of low protein diet on manganese neurotoxicity: II. Brain GABA and seizure susceptibility.

The effect of manganese (Mn2+, 3 mg/ml drinking water) on brain GABA content and electroshock seizure susceptibility in low (10% casein) and normal (21% casein) protein fed rats were investigated. Manganese exposure caused a decrease in the brain GABA content, lowered the seizure threshold and increased the seizure duration. These effects were more marked in the low protein fed rats. Diet rehabilitation caused a recovery in the GABA levels but has only a moderating effect on the seizure susceptibility and duration. An inverse correlation was observed between the brain GABA levels and seizure threshold. Results indicate a lowered GABA-ergic activity and a functional dysbalance between the GABA-ergic-dopaminergic neuronal systems in manganese toxicity.