Effects of a nitric oxide synthase inhibitor on NMDA receptor function in organotypic hippocampal cultures.

Nitric oxide (NO) has been proposed to trigger long-term potentiation (LTP) at CA3 to CA1 synapses. We previously reported that NO synthesis inhibitors and blockers reduce an electrophysiological index of NMDA receptor activation in acute hippocampal slices. We now show that the NOS inhibitor, NG-methyl-L-arginine (MLA), also reversibly prevents LTP induction in organotypic hippocampal slices and significantly reduces a biochemical index of NMDA receptor function. These results results further indicate that MLA inhibits LTP induction by interfering with NMDA receptor functions.