Intrinsic membrane properties of spinal dorsal horn neurones modulate nociceptive information processing in vivo.
The Journal of Physiology. 2011-06-01; 589(11): 2733-2743
DOI: 10.1113/jphysiol.2011.207712
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Reali C(1), Fossat P, Landry M, Russo RE, Nagy F.
Author information:
(1)CNRS, IINS, UMR 5297, Université de Bordeaux, Neurocentre Magendie, 146 rue Leo-Saignat, 33077 Bordeaux cedex, France.
The dorsal horn of the spinal cord is the first central relay where nociceptive
inputs are processed. Based on the expression and modulation of intrinsic
electrophysiological properties in in vitro slice preparations, dorsal horn
neurones (DHNs) display different discharge patterns (tonic, plateau or
rhythmic), which shape the neurone’s response to sensory inputs. However, it is
unclear whether intrinsic properties play any role in sensory processing in vivo.
Using in vivo patch clamp recordings in the adult rat, we here examine whether
these intrinsic properties are present, and to what extent they determine the DHN
response to natural stimulation. We focused primarily on wide dynamic range
neurones in deep laminae. These cells displayed a multicomponent peripheral
receptive field, comprising an excitatory firing zone, a low-probability firing
fringe, and adjacent inhibitory zones. Deep DHNs presented similar intrinsic
properties to those observed in vitro, including plateau potentials. These
plateaus, underlying high frequency accelerating discharges and after-discharges,
were triggered by mechanical stimulation of the excitatory receptive field.
Persistent activities induced by activation of plateau potentials were
interrupted by stimulation of peripheral inhibitory zones. Moreover, we show that
plateau activation is necessary for the expression of windup in response to
repetitive, nociceptive stimulation. Finally, using the spinal nerve ligation
model of neuropathy, we demonstrate a significant increase in the proportion of
plateau neurones in deep dorsal laminae. Our data, therefore, establish that
intrinsic amplification properties are expressed within intact spinal circuits
and suggest their involvement in neuropathy-induced hyperexcitability of deep
DHNs.