Brief trains of high-frequency nerve stimulation lead to variable changes in Ca2+ levels in PSCs at the crayfish NMJ

Abstract

Our objective was to extend knowledge about the role of glia, specifically perisynaptic Schwann cells (PSCs), in synaptic transmission at the crayfish neuromuscular junction (NMJ). Though it previously was assumed that glial cells play only a passive role in synaptic functions, glial cells recently have been found to play an active role in synaptic transmission in some organisms. We used epifluorescent microscopy with Syto-61, a dye used to distinguish PSCs from nerve cells, and Fluo-4, AM, a calcium (Ca²⁺) chelator that fluoresces in the presence of calcium ions, to detect changes in calcium concentration within PSCs. An increase in Ca²⁺ concentrations within PSCs after stimulation would support the hypothesis that PSCs actively participate in synaptic transmission. In this study, we were not able to ascertain any definitive conclusions about the role of PSCs in synaptic transmission; in one trial the calcium ion concentration increased after stimulation while in other trials the calcium concentration decreased, possibly as a result of complications in experimental procedure.