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Author(s): Luz, LL
Szucs, P
Safronov, BV
Title: Peripherally driven low-threshold inhibitory inputs to lamina I local-circuit and projection neurones: a new circuit for gating pain responses
Publisher: Wiley
Issue Date: 2014
Abstract: Spinal lamina I is a key element of the pain processing system which relays primary afferent input to supraspinal areas. However, little is known about how the signal is modulated by its intrinsic network including local-circuit neurones (LCNs) and much less numerous anterolateral tract projection neurones (PNs). Here, we used whole-cell patch clamp recordings in an isolated spinal cord preparation to examine properties of identified LCNs (n = 85) and PNs (n = 73) in their functionally preserved local networks. Forty LCNs showed spontaneous rhythmic firing (2-7 Hz) at zero current injection, which persisted in the presence of blockers of fast synaptic transmission. In the remaining cases, most LCNs and PNs fired tonically in response to depolarizing current injections. We identified LCNs and PNs receiving low-threshold primary afferent-driven inhibitory inputs, which in many cases were disynaptic and temporally preceded classical high-threshold excitatory inputs. This direct inhibitory link between low-threshold afferents and PNs can function as a postsynaptic gate controlling the nociceptive information flow in the spinal cord. The LCNs were found to be integrated into the superficial dorsal horn network by their receipt of monosynaptic and disynaptic inputs from other lamina I and II neurones. One-third of LCNs and two-thirds of PNs tested responded to substance P application. Thus, substance P released by a noxious afferent stimulation may excite PNs in two ways: directly, and via the activation of presynaptic LCN circuitries. In conclusion, we have described important properties of identified lamina I neurones and their roles in a new circuit for gating pain responses.
Subject: Animals
Electric Stimulation
Excitatory Postsynaptic Potentials
In Vitro Techniques
Inhibitory Postsynaptic Potentials
Neural Inhibition/drug effects
Neural Pathways/physiopathology
Pain Perception
Rats, Wistar
Reaction Time
Signal Transduction/drug effects
Spinal Cord Dorsal Horn/drug effects
Spinal Cord Dorsal Horn/metabolism
Spinal Cord Dorsal Horn/physiopathology
Substance P/pharmacology
Synaptic Transmission
Time Factors
gamma-Aminobutyric Acid/metabolism
Source: The Journal of physiology, vol. 592(7), p. 1519-1534
Related Information: info:eu-repo/grantAgreement/FCT/5876-PPCDTI/124664/PT
Document Type: Artigo em Revista Científica Internacional
Rights: openAccess
Appears in Collections:I3S - Artigo em Revista Científica Internacional

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