The protective effect of riluzole on manganese caused disruption of glutamate–glutamine cycle in rats

The mechanisms underlying the disruption of glutamate–glutamine cycle (Glu–Gln cycle) in manganism are still unknown. To approach the concrete mechanisms, the rats were i.p. injected with different doses of MnCl2 (0, 8, 40, and 200 μmol/kg), and the levels of Mn, Glu, and Gln, the morphological and ultrastructural changes, activities of Na+-K+-ATPase, GS, and PAG, mRNA and protein expression of GS, GLAST, and GLT-1 in the striatum were investigated. In addition, the effect of 21.35 μmol/kg riluzole (Na+ channel blocker) was studied at 200 μmol/kg MnCl2. It was observed that (1) Mn and Glu levels and PAG activity increased; (2) many pathological changes occurred; (3) Gln levels, Na+-K+-ATPase and GS activities, and GS, GLAST, and GLT-1 mRNA and protein expression inhibited, does dependently. Furthermore, the research indicated that pretreatment of riluzole reversed toxic effects of MnCl2 significantly. These results suggested that Glu–Gln cycle was disrupted by Mn exposure dose dependently; riluzole might antagonize Mn neurotoxicity.