Long-Term Depression at the Crayfish Neuromuscular Junction Does Not Depend on Inhibition of Nitric Oxide Synthesis

Abstract

Research to date is controversial over the necessity of nitric oxide (NO) for the production of long-term depression (LTD) in excitatory cells. We designed our experiment to determine whether NO plays a vital role in LTD at the crayfish neuromuscular junction. We inhibited NO synthase with 0.3 mM N_?-Nitro-_L-Arginine Methyl Ester hydrochloride (L-NAME) and measured amplitudes of excitatory post-synaptic potentials in muscle cells at low and high-frequency (0.1Hz and 20Hz) stimulation. We found that LTD occurs in both the control group (cells in normal crayfish saline) and the experimental group (cells treated with L-NAME) at high-frequency stimulation. This suggests that NO is not necessary for LTD at the neuromuscular junction of the crayfish. However, some of our results suggested that NO may be necessary for facilitation.