Evidence that D-Serine is a Co-agonist to NMDA Receptors at the Crayfish Neuromuscular Junction

Abstract

N-methyl D-aspartate receptor (NMDAR), a glutamate receptor, is vital to neural cells, having been linked to the facilitation of many physiological processes such as memory, plasticity and neural development. Studies show that in brains, NMDARs rely on the neurotransmitter D-Serine to act as a co-agonist along with the neurotransmitter glutamate. Since little research has been conducted on the role of D-Serine in invertebrates, we sought to discover whether any evidence supports the role of D-Serine in co-agonistic facilitation of NMDARs in the crayfish neuromuscular junction. We measured the amplitudes of excitatory postsynaptic potentials (EPSPs) in the crayfish neuromuscular junction under two separate conditions an increased D-Serine concentration and a D-amino acid oxidase (DAO) to deplete D-Serine. Average EPSP amplitudes significantly increased in the higher concentration of D-Serine and significantly declined in the DAO condition. These results provide support for our hypothesis that D-Serine acts as a co-agonist at the glutamate receptor in the crayfish neuromuscular junction.