Exogenous Nitric Oxide Enhances Synaptic Transmission at the Crayfish Neuromuscular Junction

Abstract

Nitric oxide (NO) plays a critical role in the CNS in higher animals and at the lizard neuromuscular junction (NMJ), modulating synaptic transmission. However, whether this role is conserved at the crayfish NMJ remains unclear. In this study, we attempted to determine the exogenous and endogenous role of NO in synaptic transmission by recording excitatory post synaptic potentials (EPSPs) at the crayfish NMJ. Application of DEA-NO, a NO donor, significantly increased EPSP amplitude. However, the application of L-NAME, a Nitric Oxide Synthase (NOS) inhibitor, alone did not significantly change EPSPs. We therefore conclude that exogenous nitric oxide enhances synaptic transmission at the crayfish NMJ; however, endogenous NO is not produced tonically during low-frequency stimulations.