Tuning of Membrane Properties Regulates Subliminal Synapses in Dorsal Horn Neurons of Intact Rats

doi:10.1006/exnr.2002.7886

Experimental Neurology

Volume 175, Issue 1, May 2002, Pages 209-215

https://doi.org/10.1006/exnr.2002.7886 Get rights and content

Abstract

Functional plasticity in receptive field properties underlies the mechanism whereby spinal dorsal horn neurons encode changes in pain sensitivity following peripheral injury. Activation of “silent” or subliminal excitatory synapses was hypothesized to account for this injury-induced neural plasticity. To better characterize the mechanisms governing subliminal inputs, we adapted whole-cell patch clamp to the study of dorsal horn neurons in intact, anesthetized rats. In this report we show that the membrane properties of spinal cells correlate to functional class defined by action potential responses to cutaneous stimuli. In addition, we report the discovery of a novel “silent” population of neurons with solely subliminal excitatory inputs at rest that can be activated by membrane depolarization. Finally, an induced change in baseline membrane potential to a level nearer that of a different functional class results in a corresponding change in the responses to cutaneous stimuli of a given cell to that of the new functional class. In summary our findings suggest that biophysical membrane properties are key factors determining the functional profile of spinal neurons. The rapid change of such properties may regulate the function of silent synapses in spinal neurons and underlie rapid development of neural plasticity.

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Consistent with a proalgesic effect of GPER stimulation at the spinal level, we found that bath application of G-1 depolarized 61% of the neurons analyzed, while G15 prevented this response. Membrane properties such as resting membrane potential, membrane resistance, and time constant are correlated with the neuronal response patterns.3,74,85 The depolarizations observed with G-1 were only partial, never large enough to produce a depolarization block.
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¹: To whom correspondence should be addressed at present address: The Department of Anesthesiology & Critical Care Medicine, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, No. 42, Houston, TX 77030. Fax: (713) 745-2956. E-mail: [email protected].

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Regular ArticleTuning of Membrane Properties Regulates Subliminal Synapses in Dorsal Horn Neurons of Intact Rats

Abstract

Trends Neurosci.

Pain

Pain

Neuroscience

Pain

Prog. Neurobiol.

J. Neurosci. Methods

Brain Res.

Pain

Neuronal responses to stimulation of the cervix, uterus, colon, and skin in the rat spinal cord

J. Neurophysiol.

Responses of thoracic spinothalamic and spinoreticular cells to coronary artery occlusion

J. Neurophysiol.

Form and function of dorsal horn neurones with axons ascending the dorsal columns in cat

J. Physiol.

Attentional influences on noxious and innocuous cutaneous heat detection in humans and monkeys

J. Neurosci.

Spinal neurons specifically excited by noxious or thermal stimuli: Marginal zone of the dorsal horn

J. Neurophysiol.

Voltage-dependent properties of dendrites that eliminate location-dependent variability of synaptic input

J. Neurophysiol.

A new hypothesis of central pain

Pain Forum

The thermal grill illusion: Unmasking the burn of cold pain

Science

Substance P-mediated slow excitatory postsynaptic potential elicited in dorsal horn neurons in vivo by noxious stimulation

Proc. Natl. Acad. Sci. USA

Enhanced responses of spinothalamic tract neurons to excitatory amino acids accompany the generation of capsaicin-induced hyperalgesia in the monkey

J. Neurosci.

Neuronal plasticity and pain following peripheral tisuue inflammation or nerve injury

Regular Article
Tuning of Membrane Properties Regulates Subliminal Synapses in Dorsal Horn Neurons of Intact Rats