Please use this identifier to cite or link to this item: https://hdl.handle.net/10216/114499
Author(s): Fernandes, EC
Luz, LL
Mytakhir, O
Lukoyanov, NV
Szucs, P
Safronov, BV
Title: Diverse firing properties and Aβ-, Aδ-, and C-afferent inputs of small local circuit neurons in spinal lamina I.
Publisher: Lippincott Williams & Wilkins
Issue Date: 2016
Abstract: Spinal lamina I is a key element of the pain processing system, which integrates primary afferent input and relays it to supraspinal areas. More than 90% of neurons in this layer are local circuit neurons, whose role in the signal processing is poorly understood. We performed whole-cell recordings in a spinal cord preparation with attached dorsal roots to examine morphological features and physiological properties of small local circuit neurons (n = 47) in lamina I. Cells successfully filled with biocytin (n = 17) had fusiform (n = 10), flattened (n = 4), and multipolar (n = 3) somatodendritic morphology; their axons branched extensively and terminated in laminae I-III. Intrinsic firing properties were diverse; in addition to standard tonic (n = 16), adapting (n = 7), and delayed (n = 6) patterns, small local circuit neurons also generated rhythmic discharges (n = 6) and plateau potentials (n = 10), the latter were suppressed by the L-type Ca(2+)-channel blocker nifedipine. The neurons received monosynaptic inputs from Aδ and C afferents and could generate bursts of spikes on the root stimulation. In addition, we identified lamina I neurons (n = 7) with direct inputs from the low-threshold Aβ afferents, which could be picked up by ventral dendrites protruding to lamina III. Stimulation of afferents also evoked a disynaptic inhibition of neurons. Thus, small local circuit neurons exhibit diverse firing properties, can generate rhythmic discharges and plateau potentials, and their dendrites extending into several laminae allow broad integration of Aβ-, Aδ-, and C-afferent inputs. These properties are required for processing diverse modalities of nociceptive inputs in lamina I and may underlie spinal sensitization to pain.
Subject: Action Potentials/physiology
Animals
Animals, Newborn
Biophysics
Electric Stimulation
Excitatory Postsynaptic Potentials/physiology
Functional Laterality
In Vitro Techniques
Interneurons/physiology
Nerve Fibers, yelinated/physiology
Nerve Fibers, Unmyelinated/physiology
Nerve Net/cytology
Patch-Clamp Techniques
Rats
Rats, Wistar
Spinal Cord Dorsal Horn/cytology
URI: http://hdl.handle.net/10216/114499
Source: Pain, vol. 157(2), p. 475-487
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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