The C. elegans Glutamate Receptor Subunit NMR-1 Is Required for Slow NMDA-Activated Currents that Regulate Reversal Frequency during Locomotion

The N-methyl-D-aspartate (NMDA) subtype of glutamate receptor is important for synaptic plasticity and nervous system development and function. We have used genetic and electrophysiological methods to demonstrate that NMR-1, a Caenorhabditis elegans NMDA-type ionotropic glutamate receptor subunit, plays a role in the control of movement and foraging behavior. nmr-1 mutants show a lower probability of switching from forward to backward movement and a reduced ability to navigate a complex environment. Electrical recordings from the interneuron AVA show that NMDA-dependent currents are selectively disrupted in nmr-1 mutants. We also show that a slowly desensitizing variant of a non-NMDA receptor can rescue the nmr-1 mutant phenotype. We propose that NMDA receptors in C. elegans provide long-lived currents that modulate the frequency of movement reversals during foraging behavior.