Neuropathic pain affects over 3% of the U.S. population. It is described as being severe, persistent and highly resistant to conventional treatment. As such, neuropathic pain results in life-long suffering and decreased quality of life for these patients. The mechanisms underlying the development and persistence of neuropathic pain remain unclear;however, there are several factors that could contribute to its development, including astroglial and microglial activation in the spinal dorsal horn (SDH) and activation of satellite glial cells in the dorsal root ganglia (DRG). All of these factors can contribute to increased hyperexcitability of DRG and SDH neurons, which increases pain transmission. Following nerve injury in the central nervous system, cell cycle pathways are activated that lead to astroglial proliferation and microglial activation with inflammation. This response to cell cycl activation may contribute to the development of central neuropathic pain. The purpose of this study is to examine the role of the cell cycle in peripheral neuropathic pain and test our hypothesis that inhibiting the cell cycle pathway decreases neuronal hyperexcitability and mechanical allodynia after peripheral nerve injury, likely by reducing astrogliosis in the spinal cord and satellite glial cell activation in the DRG. Using nocifensive behavioral testing, electrophysiological recording, Western blot and immunohistochemical analyses in a mouse model of peripheral nerve injury (partial sciatic nerve ligation), we will test our hypothesis with the following Specific Aims.
Specific Aim 1 : To demonstrate that the cell cycle pathway is activated in the spinal dorsal horn (SDH) and dorsal root ganglia (DRG) in a mouse model of peripheral nerve injury.
Specific Aim 2 : To demonstrate that inhibiting cell cycle activation in th SDH and DRG decreases allodynia and neuronal hyperexcitability after peripheral nerve injury. The results of this study will be highly important and quickly translatable from the preclinical to the clinical setting, since several cell cycle inhibitor drugs are already in clinical trials for cncer treatment. The findings from this study will also have a broad impact and increase our mechanistic knowledge across chronic pain states.

Public Health Relevance

Neuropathic pain continues to be a serious healthcare concern that is severe, persistent and highly resistant to conventional pain therapies, resulting i lifelong suffering and decreased quality of life for these patients. It is also extraordinarily cosly to patients, families and society. We will investigate whether inhibiting the cell cycle pathway wil decrease neuropathic pain from sciatic nerve injury with the goal to prevent and/or better manage neuropathic pain.

National Institute of Health (NIH)
National Institute of Nursing Research (NINR)
Exploratory/Developmental Grants (R21)
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Special Emphasis Panel (ZRG1-NRCS-G (08))
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Marden, Susan F
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University of Maryland Baltimore
Schools of Nursing
United States
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Wu, Junfang; Zhao, Zaorui; Zhu, Xiya et al. (2016) Cell cycle inhibition limits development and maintenance of neuropathic pain following spinal cord injury. Pain 157:488-503
Lipinski, Marta M; Wu, Junfang; Faden, Alan I et al. (2015) Function and Mechanisms of Autophagy in Brain and Spinal Cord Trauma. Antioxid Redox Signal 23:565-77
Wu, Junfang; Zhao, Zaorui; Sabirzhanov, Boris et al. (2014) Spinal cord injury causes brain inflammation associated with cognitive and affective changes: role of cell cycle pathways. J Neurosci 34:10989-1006
Wu, Junfang; Stoica, Bogdan A; Luo, Tao et al. (2014) Isolated spinal cord contusion in rats induces chronic brain neuroinflammation, neurodegeneration, and cognitive impairment. Involvement of cell cycle activation. Cell Cycle 13:2446-58