alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors modulate dopamine release in rat hippocampus and...

The effects of infusing the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) on the release of dopamine (DA) has been studied in rat hippocampus and striatum in vivo. In hippocampus, AMPA (1-10 microM) produced a dose related increase in dialysate DA, but at 100 microM AMPA a sustained decrease in extracellular DA was observed. However, when samples were collected at 5-min intervals 100 microM AMPA infusion revealed a brief increase in hippocampal dialysate DA. Infusion of 100 microM AMPA and 500 microM diazoxide, which blocks AMPA receptor desensitization, led to a marked increase in extracellular DA, as did diazoxide alone, although to a lesser extent. The AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3,-dione (CNQX; 200 microM) reversed the effect of AMPA and/or diazoxide infusion on dialysate DA and when infused alone, CNQX also decreased hippocampal dialysate DA. AMPA (50-500 microM) increased striatal DA release. The effect of AMPA on extracellular DA was reversed by CNQX (200 microM). Diazoxide infusion caused a decrease in striatal DA release, and this was not affected by CNQX. These data suggest that hippocampal, but not striatal AMPA receptor desensitization may play a role in regulating DA release.