Pain is an unpleasant sensation that is experienced when signals generated in specific peripheral receptors (nociceptors) by a (potentially) damaging stimulus reach the somatosensory cortex. Pain information reaches the spinal cord via unmyelinated or thinly myelinated central processes of small diameter nociceptors located in the dorsal root ganglia. Nociceptive signals en route to the brain are then integrated at the level of the dorsal horn of the spinal gray matter where the synapses with second order sensory neurons are located. These synapses are the target of a complex network of spinal interneurons that is mainly localized in lamina II (substantia gelatinosa) of the gray matter. Transmission/modulation of nociceptive inputs in lamina II is, in turn, mediated by an impressive number of neurotransmitters. The low molecular weight glutamate, GABA, and glycine are responsible for fast neurotransmission and likely involved in rapid adaptive responses to noxious stimuli. The high molecular weight peptides, instead, produce slower and long lasting responses that may drastically influence chronic pain. In addition, recent work has unraveled the circuitry made by a subpopulation of nociceptors expressing the growth factors BDNF and GDNF. The latter appears to be specifically responsible for a cross-talk between peptidergic and nonpeptidergic nociceptive primary afferents under inflammatory conditions. Much of the progress in our comprehension of neuronal circuitry and neurotransmission in mammalian substantia gelatinosa comes from histologic and functional studies on animal models that will be here discussed also on comparative bases.

Pain circuitry in animal models

MERIGHI, Adalberto
2013-01-01

Abstract

Pain is an unpleasant sensation that is experienced when signals generated in specific peripheral receptors (nociceptors) by a (potentially) damaging stimulus reach the somatosensory cortex. Pain information reaches the spinal cord via unmyelinated or thinly myelinated central processes of small diameter nociceptors located in the dorsal root ganglia. Nociceptive signals en route to the brain are then integrated at the level of the dorsal horn of the spinal gray matter where the synapses with second order sensory neurons are located. These synapses are the target of a complex network of spinal interneurons that is mainly localized in lamina II (substantia gelatinosa) of the gray matter. Transmission/modulation of nociceptive inputs in lamina II is, in turn, mediated by an impressive number of neurotransmitters. The low molecular weight glutamate, GABA, and glycine are responsible for fast neurotransmission and likely involved in rapid adaptive responses to noxious stimuli. The high molecular weight peptides, instead, produce slower and long lasting responses that may drastically influence chronic pain. In addition, recent work has unraveled the circuitry made by a subpopulation of nociceptors expressing the growth factors BDNF and GDNF. The latter appears to be specifically responsible for a cross-talk between peptidergic and nonpeptidergic nociceptive primary afferents under inflammatory conditions. Much of the progress in our comprehension of neuronal circuitry and neurotransmission in mammalian substantia gelatinosa comes from histologic and functional studies on animal models that will be here discussed also on comparative bases.
2013
Animal pain recognition and management in biomedical and veterinary research
Imola (BO)
18-19 ottobre 2013
63
6
539
539
Dolore; modulazione del dolore
Merighi A
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/152211
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