The Glutamatergic System in Primary Somatosensory Neurons and Its Involvement in Sensory Input-Dependent Plasticity

Abstract

Glutamate is the most common neurotransmitter in both the central and the peripheral nervous system. Glutamate is present in all types of neurons in sensory ganglia, and is released not only from their peripheral and central axon terminals but also from their cell bodies. Consistently, these neurons express ionotropic and metabotropic receptors, as well as other molecules involved in the synthesis, transport and release of the neurotransmitter. Primary sensory neurons are the first neurons in the sensory channels, which receive information from the periphery, and are thus key players in the sensory transduction and in the transmission of this information to higher centers in the pathway. These neurons are tightly enclosed by satellite glial cells, which also express several ionotropic and metabotropic glutamate receptors, and display increases in intracellular calcium accompanying the release of glutamate. One of the main interests in our group has been the study of the implication of the peripheral nervous system in sensory-dependent plasticity. Recently, we have provided novel evidence in favor of morphological changes in first- and second-order neurons of the trigeminal system after sustained alterations of the sensory input. Moreover, these anatomical changes are paralleled by several molecular changes, among which those related to glutamatergic neurotransmission are particularly relevant. In this review, we will describe the state of the art of the glutamatergic system in sensory ganglia and its involvement in input-dependent plasticity, a fundamental ground for advancing our knowledge of the neural mechanisms of learning and adaptation, reaction to injury, and chronic pain.

TRPV4 and TRPM8 as putative targets for chronic low back pain alleviation

“…These observations suggest that the TRP channel increase could be related to the higher infiltration by nervous fibers in pathological samples. These results are aligned with previous studies that identified these channels on axons in peripheral tissues [8]. TRP channels act as sensors of various stimuli in peripheral sensory neurons.…”

Glial Cell AMPA Receptors in Nervous System Health, Injury and Disease

“…SGCs are in close contact with neurons, ensheathing them and playing a role in neurotransmission and glutamate homeostasis [25,259,260,272]. To that end, SGCs express several glutamate transporters, metabotropic glutamate receptors, NMDAR, KR and AMPAR [259,260]. Regarding AMPAR, SGCs express mainly GluA4 and in lesser quantities GluA2/3 but no GluA1 [259,273].…”

Activating metabotropic glutamate receptor‑7 attenuates visceral hypersensitivity in neonatal maternally separated rats

“…L-Glutamate is the major excitatory neurotransmitter in the central nervous system. The actions of glutamate are modulated by ionotropic receptors and metabotropic glutamate receptors (mGluRs) (5). Based on sequence homology and signal transduction mechanisms, mGluRs have been divided into groups I, II and III; mGluR4, mGluR6, mGluR7 and mGluR8 are group III mGluRs (5,6).…”

“…The actions of glutamate are modulated by ionotropic receptors and metabotropic glutamate receptors (mGluRs) (5). Based on sequence homology and signal transduction mechanisms, mGluRs have been divided into groups I, II and III; mGluR4, mGluR6, mGluR7 and mGluR8 are group III mGluRs (5,6). These receptors can modulate the effect and release of glutamate in the central nervous system (7).…”