The Journal of Neuroscience, 2001, 21:RC169:1-6
RAPID COMMUNICATION
Sensitization of Dorsal Horn Neurons in a Two-Compartment
Cell Culture Model: Wind-Up and Long-Term Potentiation- Like
Responses
Kristina S.
Vikman,
Krister
Kristensson, and
Russell H.
Hill
Department of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm, Sweden
One of the main characteristics of central sensitization associated
with postinjury pain and chronic pain is increased excitability of the
dorsal horn neurons in the spinal cord. Two electrophysiological features associated with the origin and modulation of central sensitization are wind-up of action potential frequency and
long-term potentiation (LTP), which have been demonstrated previously
in the intact dorsal horn. Here we present evidence for electrically evoked sensitization of dorsal horn neurons in a two-compartment cell
culture system of rat dorsal root ganglia (DRGs) and dorsal horn
neurons. Whole-cell recordings of dorsal horn neurons showed that
repetitive low-frequency stimulation of DRG axons induced a
frequency-dependent cumulative depolarization of the membrane potential
with a concomitant increase in action potential frequency in a subset
of neurons (41%). The characteristics presented here for dissociated
cells are in accordance with those ascribed to classical wind-up in the
intact dorsal horn. In addition, tetanic stimulation of DRG axons
resulted in a significant increase in the number of action potentials
in response to test stimuli in 42% of the cells tested. This prolonged
potentiation of neuronal excitability in the dorsal horn lasted
throughout the recording period (>1 hr) and tended to be voltage
dependent in an LTP-like manner. To our knowledge, this is the first
time that wind-up and LTP-like responses are reported for dorsal horn
neurons in cell culture.
Key words:
DRG; nociception; pain; patch clamp; spinal cord; stimulus-evoked potentials; synaptic plasticity
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