Glutamatergic innervation of rat skeletal muscle by supraspinal neurons: a new paradigm in spinal cord injury repair

Acetylcholine is the specific chemical code of spinal nerve terminal transmission at the mammalian neuromuscular junction (NMJ), whereas nicotinic acetylcholine receptors inserted into the membrane of muscle fibres mediate signalling for the muscle response. Glutamate has a primary role in neuromuscular transmission of organisms that are phylogenetically distant from mammals, the invertebrates, including insect and molluscs. Recent research has shown that diverting descending glutamatergic fibres in the spinal cord to rat skeletal muscle by means of a peripheral nerve graft causes the cholinergic synapse to switch to the glutamatergic type. These data demonstrate that under appropriate surgical manipulation supraspinal neurons can directly target muscle fibres and specify the postsynaptic receptors to achieve a functional glutamatergic NMJ.