Mammalian neuromuscular junctions: modern tools to monitor synaptic form and function

Studies of neuromuscular synaptic structure and function have, historically, given general insights into synaptic mechanisms, whose principles were then extended to most other chemical synapses in diverse nervous systems. Often, these insights have been acquired through rigorous application of novel tools. Here, two genetic approaches to the visualisation of neuromuscular form and physiology are highlighted: first, mice expressing spectral variants of green fluorescent protein in neurones, axons and motor nerve terminals, including the 'brainbow' mouse transgenic lines. Second, the expression of pH-sensitive indicators of exocytosis and endocytosis in synaptopHluorin mice has uncovered intriguing facets to the regulation of synaptic strength. This transgenic approach, in addition to facilitating achievement of the goal to define brain connectivity and synaptic function at a cellular level, also points to ways of appraising new therapeutic avenues focused on synaptic involvement in neurodegenerative diseases.