Our research focuses on the neural mechanisms of pain and itch. Experiments on pain examine the functional properties of dorsal root ganglion (DRG) neurons in the rodent. We are currently interested in how electrophysiological and neurochemical changes in these properties, occurring after a chronic compression of the DRG (CCD model), lead to behavioral signs of neuropathic pain. This type of pain might be produced in humans after injuries and degenerative disorders of the spine. Our experiments on itch use psychophysical methods in humans and behavioral testing in animals to measure itch and nociceptive sensations that can occur under normal conditions and after inflammatory or neuropathic disorders affecting the skin.
In our animal models, the neural encoding of normal and pathological itch vs. pain is measured using imaging and electrophysiological recordings of visualized sensory neurons in vitro and in vivo. Transgenic mice are used that express a fluorescent marker in a subset of itch or pain mediating DRG neuron to facilitate identification for functional studies. A major goal is to identify neurons and neurochemical mechanisms that could be targeted in clinical treatments of chronic pruritus or pain.
- Han, L., Ma, C., Liu, Q., Weng, H.J., Cui, Y., Tang, Z., Kim, Y., Nie, H., Qu, L., Patel, K.N., Li, Z., McNeil, B., He, S., Guan, Y., Xiao, B., LaMotte, R.H. & Dong, X. (2012). A subpopulation of nociceptors specifically linked to itch. Nature Neuroscienc
- Liu, Q., Sikand, P., Ma, C., Tang, Z., Han, L., Li, Z., Sun, S., LaMotte, R.H. & Dong, X. (2012). Mechanisms of itch evoked by beta-alanine. Journal of Neuroscience 32(42), 14532–14537. PMCID: PMC3491570
- Ma C, Nie H, Gu Q, Sikand P, LaMotte RH. In-vivo responses of cutaneous C-mechanosensitive neurons in mouse to punctate chemical stimuli that elicit itch and nociceptive sensations in humans. J. Neurophysiol 107(1):357-63, 2012.
- Fan N, Donnelly DF, LaMotte RH. Chronic compression of mouse dorsal root ganglion alters voltage-gated sodium and potassium currents in medium-sized dorsal root ganglion neurons. J. Neurophysiol 106(6):3067-72, 2011.
- Sikand P, Dong X, LaMotte RH. BAM8-22 peptide produces itch and nociceptive sensations in humans independent of histamine release. J. Neurosci. 31(20):7563–7567, 2011.
- Ringkamp M, Schepers RJ, Shimada SG, Johanek LM, Hartke TV, Borzan J, Shim B, LaMotte RH, Meyer RA. A role for nociceptive, myelinated nerve fibers in itch sensation. J. Neurosci. (In press).
- Sikand P, Shimada SG, Green BG, LaMotte RH. Sensory responses to injection and punctate application of capsaicin and histamine to the skin. Pain. 2011 Jul 28. [Epub ahead of print] PMID: 21802851.
- LaMotte RH, Shimada SG, Sikand P. Mouse models of acute, chemical itch and pain in humans. Exp. Derm. 20(10):xxxx, 2011 (in press).
- Fan N, Sikand P, Donnelly DF, Ma C, LaMotte RH. Increased sodium and potassium currents in small mouse dorsal root ganglion neurons after ganglion compression. J Neurophysiol. 2011 Jul;106(1):211-8. PMID: 21525373
- Ma C, Donnelly DF, LaMotte RH. In vivo visualization and functional characterization of primary somatic neurons.J Neurosci Methods. 191(1):60-65, 2010. PMCID: PMC2933835
- LaMotte RH et al. (2009) Pruritic and nociceptive sensations and dysesthesias from a spicule of cowhage, J. Neurophysiol., 101(3):1430-1443, 2009. PMID: 19144738 PMC2666414.
- Shimada SG and LaMotte RH (2008) Behavioral differentiation between itch and pain in mouse, Pain, 139, 681, Published