The Effects of Protein Synthesis on Long-Term Synaptic Depression at the Crayfish Neuromuscular Junction

Abstract

Long-term synaptic depression (LTD) has been implicated as a mechanism of information storage in the human brain. We studied the role of protein synthesis on LTD at the crayfish neuromuscular junction, whose synaptic connectivity resembles the human central nervous system. Previous studies have investigated presynaptic calcium current at the phasic F3 motoneuron and suggested that Ca²⁺ influx induces a protein synthesis pathway that leads to LTD. In this study, we successfully induced LTD at the F3 neuromuscular junction by applying a 46V stimulus at a frequency of 0.6 pps for two hours. Moreover, we examined LTD by measuring the change in EPP amplitude. In addition, we attenuated LTD after exposing the crayfish preparation to cycloheximide (CHX), which inhibits protein synthesis. Our results provide evidence that protein synthesis is necessary for LTD induction and may support the theory that LTD in crayfish is presynaptic in origin.